Stargazer Columns 2011

Dec. 23, 2011: January 2012
Dec. 09, 2011: Tycho Brahe, an Unlikely Revolutionary
Nov. 25, 2011: December 2011
Nov. 11, 2011: Buying a Telescope for the Holidays?
Oct. 28, 2011: November 2011
Oct. 14, 2011: Mystery Sighting
Sep. 23, 2011: October 2011
Sep. 09, 2011: Comet Elenin and Other Fables
Aug. 26, 2011: September 2011
Aug. 12, 2011: Constellations
July 29, 2011: August 2011
July 08, 2011: Seeing Is Believing...or Is It?
June 24, 2011: July 2011
June 10, 2011: Summer Solstice - the Sun Goes North for the Summer
May 28, 2011: June 2011
May 13, 2011: Cosmic Baseball
Apr. 22, 2011: May 2011
Apr. 08, 2011: Maria Mitchell - Trail-blazer
Mar. 25, 2011: April 2011
Mar. 11, 2011: Getting to Know Our Solar System: Moon
Feb. 25, 2011: March 2011
Feb. 11, 2011: Giordano Bruno: Martyr or Fool?
Jan. 22, 2011: Angular Distances
Jan. 08, 2011: The Great Winter Arc

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December 23, 2011
Stargazer #571

January 2012

This chart shows the night sky as appears at 9 p.m. early in the month, 8 p.m. at mid month, and 7 p.m. late in the month from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Jan. 1 – Sunrise: 7:28 a.m.; Sunset: 5:36 p.m. / Jan. 15 – Sunrise: 7:28 a.m.; Sunset: 5:48 p.m. / Jan. 31 – Sunrise: 7:22 a.m.; Sunset: 6:02 p.m. (Times exact for Waco, TX)

• Moon
  Jan. 1: 1st Quarter / Jan. 9: Full / Jan. 16: 3rd Quarter / Jan. 23: New / Jan. 30: 1st Quarter

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  Jan. 1 Sun. evening: The Moon is at 1st quarter.
  2 Tue. evening: The gibbous Moon is 5 degrees above bright Jupiter high in the south.
  4 Thu. morning: The Quadrantid meteor shower peaks in the north – best between 3:20 a.m. moonset and dawn.
  4 Thu.: Earth is at perihelion – it nearest point to the Sun (91.4 million miles) in its annual elliptical orbit around our star.
  9 Mon.: The Moon is full.
  13 Fri.: Friday the 13th is an unlucky day for the superstitious, but you can avoid bad luck by not being superstitious.
  13 Fri. morning: The gibbous Moon is a fist-width (held at arm's length) to the lower right of Mars high in the southwest, and is the same distance to the lower left the next evening.
  13 Fri. evening: Brilliant Venus is two moonwidths to the left of much fainter Neptune low in the west southwest; seeing Neptune requires at least binoculars or a small telescope.
  16 Mon. morning: The 3rd quarter Moon (lower right), the star Spica (4 degrees above the Moon), and the planet Saturn (7 degrees to their left) form a triangle high in the south southeast.
  19 Thu. morning: The crescent Moon is 4 degrees to the upper left of Scorpius' brightest star Antares low in the southeast before dawn.
  23 Mon.: The Moon is new – between the Sun and Earth.
  25 Wed. evening: The crescent Moon is a fist-width (9 degrees) to the lower right of Venus low in the west in the early evening, and then the same distance (8 degrees) to the upper right the next evening.
  29 Sun. evening: The Moon is 7 degrees to the lower right of Jupiter high in the south, and 8 degrees above the giant planet the next evening.
  30 Mon. evening: The Moon is at 1st quarter for the second time this month.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Venus, Jupiter
  Mornings: Mercury (early in the month), Saturn, Mars
  * Mercury is low in the east southeast early in the month, then spends the rest of January in the Sun.
  * Venus is the brilliant “evening star” in the west.
  * Mars now rises before midnight and is high in the southwest in the morning.
  * Jupiter, high in the southwest in the evening, sets after midnight.
  * Saturn is up after midnight and high in the south southeast in the morning.
  

• Circumpolar Region in Winter
  
  Polaris, popularly known as the North Star, is the star which, by chance, happens to be almost exactly straight up from Earth's North Pole. As such, it is the only star which seems never to move, always being in the same place any time of night and every night of the year.
  As Earth rotates on its axis, all the other stars appear to circle Polaris slowly in a counterclockwise direction every 24 hours. Some are near enough to Polaris that they never dip below the horizon and are always in the sky. These stars, and the constellations they form, are referred to as circumpolar, and their area of the sky is the Circumpolar Region.
  [Image: Star trails over the Central Texas Astonomical Society's Meyer Observatory; photo taken by CTAS member Dick Campbell of Hewitt (Waco), TX.]
  The Circumpolar Region is one of the nine sky regions we'll be presenting in this column over the next year, and is the only region that varies in size depending up the geographic location of the viewer. Since Polaris doesn't move, its altitude as seen in the sky is always the same number of degrees above the horizon as the degrees of latitude from which it is seen. For example, with Waco's latitude of 31° N, Polaris is always 31 degrees above Waco's northern horizon, and all the stars within 31 degrees of Polaris form the Circumpolar Region as seen from Waco.
  In Bangor, Maine, however, the Circumpolar Region would be larger. Given Bangor's latitude of 45° N, Polaris is seen at 45 degrees altitude, and thus more stars are circumpolar.
  The Circumpolar Region as seen from most mid-northern latitudes (most of the U.S.) contains six constellations, all or most of each being visible all night and all year. These constellations are Ursa Minor the Little Bear, Ursa Major the Big Bear, Cassiopeia the Queen, Cepheus the King, Draco the Dragon, and Camelopardalis the Giraffe. Owing the seasonal variations, different of these constellations are prominent in the different seasons.
  Ursa Minor, always at the center of the Circumpolar Region, contains the Little Dipper with Polaris at the end of the dipper's handle. In the evenings of winter, most of the Little Dipper is to Polaris' lower right with Ursa Major, which contains the well-known Big Dipper, further to the right. The Little Dipper, composed of mostly fainter stars, is far more difficult to make out than its larger and easier-to-identify counterpart.
  To Polaris' left and lower left are Cassiopeia and her husband Cepheus. Cassiopeia now looks like a “M” or “W” on its side and is brighter than Cepheus which looks rather like a stick-house.
  Draco, now situated between Polaris and the horizon, is now difficult to see because it is low. Above Polaris is Camelopardalis which is also hard to see, but for a different reason – it contains no bright stars.
  Although all or part of all these constellations are in the night sky year-around, different ones move into prominence as the seasons progress. During the coming year we'll look at the Circumpolar Region again for its spring, summer, and fall appearances. Next month, we'll introduce the Great Winter Arc Region featuring Orion the Hunter.

• Star Parties. The Central Texas Astronomical Society, which owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX, will have it next free, monthly observatory open house Sat., Jan. 14, 6-8 p.m. See www.centexastronomy.org for more information.

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December 9, 2011
Stargazer #570

Tycho Brahe, an Unlikely Revolutionary

December 14 is the 465th birthday of Danish astronomer Tycho Brahe (1546-1601), one of five key players in the 150-year long Copernican revolution – a revolution he didn't even fully support.

Up to their time, it was believed the Earth was the center of all creation, a view called the geocentric theory. In the 1530s, Nicolaus Copernicus (1473-1543) postulated that the Sun was at the center, called the heliocentric theory – but he had no observational evidence to support his radical theory. With the newly invented telescope, Galileo Galilei (1564-1642) began finding supporting evidence in 1610, but using the then-prevailing view that planetary orbits are circular, the heliocentric theory still wasn't convincing.

About this same time, Johannes Kepler (1571-1634) discovered that planetary orbits are elliptical, not circular, and when this was applied to Copernicus' heliocentric view, things fell into place – although ironically Galileo was never convinced of elliptical orbits. The fifth player, Isaac Newton (1642-1727), in the 1680s discovered and set forth the laws of gravity to further explain planetary motions. So where did Tycho Brahe come in? He furnished the data without which mathematician Kepler would never have discovered elliptical orbits.

The son of a prominent Danish nobleman, Tycho's life was both colorful and full of ironies. At age 2 he was kidnapped and raised by an uncle and aunt. Before his birth his parents promised him to his father's brother and wife as they were unable to have children, however after his birth, his parents began to have second thoughts – so he was kidnapped. Apparently, no hard feelings resulted as the families remained close.

Tycho received an education befitting a nobleman, but he also had a brash tempestuousness about him that he came to regret on occasions. At age 20, he got into a duel and suffered a disfiguring injury when his rival's sword removed the bridge of his nose. Being a resourceful chap, he fashioned a prosthetic nose-piece of silver and gold which he affixed with a wax paste and wore the rest of his life.

At the age of 25 he fell in love with Kirstin, a Lutheran minister's daughter. Since she was a commoner and he a nobleman they couldn't officially marry, so they lived together as husband and wife, establishing a common-law marriage. It lasted 30 years until Tycho's death, and produced eight children, six of whom lived to adulthood.

His family intended that he go into law, but being star-struck at age 13 by a solar eclipse, he began his own personal astronomical studies along with his other formal studies. He quickly recognized the imprecision and inconsistencies of the astronomical books and charts of the day, and at age 17, set forth his life goal when he wrote:

“I've studied all available charts of the planets and stars and none of them match the others. There are just as many measurements and methods as there are astronomers and all of them disagree. What's needed is a long term project with the aim of mapping the heavens conducted from a single location over a period of several years.” Truly remarkable for a renaissance teenager.

In 1573, he wrote De Stella Nova about a “new star” he had observed the previous year – now known as Supernova 1572.

In 1576, at age 29, Tycho was given, by the king of Denmark, the small island of Hven and funds for the construction of an observatory. Here he spent much of the next 20 years making the observations for which he is famous.

He constructed many of his own astronomical instruments and invented others. Born with exceptional eyesight, he became one of the great observers in astronomical history. Ironically he died eight years before the invention of the telescope – the instrument that revolutionized observational astronomy.

[Image: Wood carving depicting Tycho in his observatory with his mural (wall) quadrant.]

With remarkable precision, he charted the locations of 777 stars and compiled tables of motions of the then-known five planets. Shortly before his death, Tycho was joined by the 29-year old mathematician Johannes Kepler in what proved to be a scientifically fateful collaboration. They worked together only a year or so, but following Tycho's death, Kepler used Tycho's 20 years of measurements of the positions of Mars to discover the elliptical nature of planetary orbits – an enormously significant contribution to the Copernican revolution.

Ironically, although Tycho was a contemporary of Galileo, there is no indication they ever met. In fact, Galileo, 18 years younger, was a mathematics professor who didn't get into astronomy seriously until after Tycho's death.

While Tycho reportedly admired Copernicus, he never knew him, having been born three years after Copernicus died. Furthermore, he never came to agree with Copernicus' heliocentric theory, and even came up with his own theory, known as the Tychonic system, which enjoyed favor for a time. Yet, it was his accurate and meticulously recorded observations that doomed his own theory and led to the eventual acceptance of Copernicus'.

[Image: Eduard Ender painting believed to be Tycho demonstrating a celestial globe to his last benefactor Emperor Rudolph II in Prague.]

Tycho Brahe died rather suddenly at the age of 54, and the cause of his death is still a mystery. Initially attributed to kidney stone complications, his body was exhumed in 1901 and when no stones were found, the cause of death was cited as uremia. Later studies found toxic levels of mercury in his body – he also dabbled in alchemy – and it is now believed he died from mercury poisoning.

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November 25, 2011
Stargazer #569

December 2011

This chart shows the night sky as appears on the 1st at 9 p.m., on the 15th at 8 p.m., and on the 31th at 7 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Dec. 1 – Sunrise: 7:10 a.m.; Sunset: 5:25 p.m. / Dec. 15 – Sunrise: 7:20 a.m.; Sunset: 5:27 p.m. / Dec. 31 – Sunrise: 7:28 a.m.; Sunset: 5:36 p.m. (Times exact for Waco, TX)

• Moon
  Dec. 2: 1st Quarter / Dec. 10: Full / Dec. 17: 3rd Quarter / Dec. 24: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  2 Fri. evening: The Moon is at 1st quarter.
  4 Sun.: Mercury is in inferior conjunction between Earth and Sun, passing into the morning sky.
  6 Tue. evening: The large gibbous Moon is to the left of bright Jupiter.
  10 Sat.: The full Moon, called the Moon Before Yule and the Long Night Moon, features a total lunar eclipse visible only over the extreme western and northwestern U.S., the Pacific, and the far east.
  13 Tue. all night: The Geminid meteor shower peaks with the best chance of seeing meteors before the 10:30 p.m. moonrise; face east and look upward.
  17 Sat. morning: The 3rd quarter Moon is below Mars high in the south.
  9 Mon.: Saturnalia, an ancient Roman festival honoring the god Saturn, father of Jupiter.
  19 Mon. morning: A waning crescent Moon is a fist-width (held at arm's length) to the right of Saturn with the star Spica between them; the next morning the Moon is below them.
  21 Wed.: Winter solstice – Northern Hemisphere’s first day of winter and shortest day of year.
  22 Thu. morning: A thin crescent Moon is to the upper right of Mercury and straight above the star Antares which is near the southeastern horizon; binoculars will help in spotting Mercury and Antares.
  22 Thu. all night: The Ursid meteor shower peaks with the best chance of seeing meteors coming after midnight; face north and look upward.
  24 Sat.: The Moon is new.
  26 Mon. early evening: At dusk the crescent Moon is to the lower right of Venus low in the west southwest, and above the brilliant “evening star” the next night.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Venus and Mercury (setting in west southwest), Jupiter (east)
  Mornings: Saturn (very low in east); Mars (east), Jupiter (low in west)
  * Mercury is near the southwestern horizon at dusk, just below Venus, most of the month.
  * Venus is climbing higher daily, becoming the prominent “evening star” in the west.
  * Mars is up in the east well before sunrise.
  * Jupiter is well up in the southeast in the early evening and high in the west by morning.
  * Saturn is beginning to emerge from the glare of the rising Sun low in the east at dawn.
  

• Emergence of the “Evening Star”
  
  The planet Venus is emerging in our evening sky for its stint as the “evening star” until well into 2012. Now setting nearly two hours after sunset, it is getting slightly farther above the setting Sun each evening, and will be at its best in late March when it will dominate the western sky for nearly four hours after sunset. It sinks back into the setting Sun in late May after which it once again becomes the “morning star” in June. Other than the Moon and an occasional fleeting super-bright meteor, Venus is the brightest natural object in the night sky – brighter than any star or other planet.

• Night Sky Regions
  
  On any clear, moonless night away from city lights, the night sky appears to be filled with millions of stars, so no wonder learning the night sky can seem so daunting. But while there really are millions of stars in our section of our Milky Way galaxy, we can't see near that many with our naked eyes.
  Surprisingly, under reasonably dark skies, most of us see only several hundred individual stars on any given night, and less than three thousand are ever visible from planet Earth without optical aids – and the vast majority of those are quite faint.
  Brighter stars number in the dozens with only 21being in the brightest category called 1st-magnitude stars. So, you're thinking, maybe I could learn the names of 21 stars, but then what about finding them.
  That's were constellations come in. Using bright and moderately bright stars, and lots of human imagination, the ancients invented constellations to help them learn the night sky. Of the countless hundreds of imaginary sky pictures made up over the millennia, today only 88 official constellations are recognized by the International Astronomical Union.
  Admittedly, 88 constellations is a lot to learn, but we can make it easier. Of those 88, nearly three dozen are too far south ever to be visible from our mid-northern latitudes ,or are faint and devoid of interesting naked eye objects. Thus, by learning some 50 constellations, one can be quite at home in the night sky.
  Since even that's still rather challenging, I found it helpful to partition the night sky into nine regions. With each region I associate a theme or story to tie together the region's constellations. Some come from antiquity; others I made up. These nine regions helped me learn my way around the night sky, and they have helped students in my stargazing classes – so maybe you will find them helpful as well.
  Over the next year in this column, we will present each region, one each month. As a preview, here are the nine regions with the season(s) each is best seen: Circumpolar (year around); Great Winter Arc (winter); Southern Ship (late winter); Cosmic Baseball (spring, early summer); Macho Quadrangle (summer); Sagittarius' Tea Party (summer); Milky Way Triangle (summer, fall); Andromeda's Rescue (fall); and Water World (fall). Next month we'll look at the Circumpolar Region as seen in the winter.

• Astro Milestones. Dec. 14 is the birthday of Danish astronomer Tycho Brahe (1546-1601). Dec. 25 is the birthday of Isaac Newton (1642-1727), father of modern physics. Dec. 27 is the birthday of Johannes Kepler (1571-1630), discoverer of elliptical orbits.

• Star Parties. The Central Texas Astronomical Society, which owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX, will have it next free, monthly observatory open house Sat., Dec. 10, 6-8 p.m. See www.centexastronomy.org for more information.

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November 11, 2011
Stargazer #568

Buying a Telescope for the Holidays?

It's the time of year when many are considering buying a telescope as a holiday gift – a decision many face with many questions – and given the options available, it's no wonder. While we don't have space for Telescope Buying 101, we can offer some help in making the decision easier.

Cost. Prices range from less than $100 to thousands of dollars. The least-expensive are usually more disappointing than satisfying as they are often wobbly and finding objects can be challenging. At the other end, few can afford the big scopes, or figure out how to use them if they do. But $200 to $400, spent wisely, can purchase a fun and satisfying scope.

Binoculars. If you're not ready to spend that much for a scope, $100 or so can purchase a respectable pair of binoculars – 7x50s being a good size for stargazing as well as general viewing. Virtually all stargazers, even those with large scopes, use them. If you've never viewed the night sky with binoculars, you'll be surprised at how much more can be seen than with naked eyes.

Power. The magnifying power of a telescope is not fixed but rather depends upon the eyepiece, the part of the scope into which one actually views and which does the magnifying. Eyepieces (and thus power) can be switched out easily and quickly in the field. Most new scopes come with two or three different sizes of eyepieces producing different powers, and other sizes can be purchased later if more options (powers) are desired.

Aperture. A more relevant consideration than power is a telescope's aperture – the diameter of the “big end” – and generally bigger is better. The larger the aperture, the more light a scope gathers, and since seeing light from faint objects is what it's all about, larger apertures make objects look brighter, and can reveal objects too faint to be seen in smaller aperture scopes. Also, larger apertures scopes can generally be “pushed” to higher powers before the image becomes too fuzzy.

Types: The three basic types of telescopes are refractors, reflectors, and Cassegrains. Refractors, the first type of telescope invented in 1608 by Hans Lippershey, have an objective lens at the front end to gather light and focus it on the eyepiece at the back end.

In 1668, Isaac Newton invented reflecting telescopes, now called Newtonian reflectors. The objective lens at the front is replaced by a concave mirror at the back end which gathers and focus the light to the eyepiece. (A small interior diagonal mirror re-directs the light 90 degrees to the eyepiece placed at the side rather than at the back end.) Since mirrors are less expensive to make than lens, reflectors of a given aperture cost less than refractors of the same size. For example, a 6” reflector will generally cost much less than a 6” refractor.

The Cassegrain, designed by Laurent Cassegrain in 1672, is a variation of Newton's reflector. Both have a light-gathering concave mirror at the back, but in the Cassegrain the light is focused onto small convex mirror at the front end which re-directs the light back down the tube, through a small hole in the big mirror, and into the eyepiece at the scope's back end. Advantages of Cassegrains are their compactness and ease of portability, but with their more complex design they cost more than reflectors.

Mounts. Telescopes are attached on a mount which holds them and enables them to be pointed at objects. The three primary kinds of mounts are equatorial, fork, and altazimuth. Most, but not all, mounts are affixed atop a tripod stand. With mounts and tripods, sturdier is better.

A creative non-tripod altazimuth mount, invented in the 1960s by American amateur astronomer John Dobson, is by far the simplest and least-expensive. The rotating and pivoting base holding a Newtonian reflector scope (informally called a Dobsonian telescope, or simply a Dob) is, dollar for dollar, hard to beat.

GoTo Electronics. An increasing number of scopes have electronic “GoTo” and tracking capabilities. The GoTo feature finds objects while tracking gradually moves the scope at the same rate but in the opposite direction of Earth's rotation to keep the object visible in the eyepiece. These can be marvelous aids, but they increase a scope's cost and are rarely as simple to use as the advertising claims.

Using. When you get a new scope, don't expect to set it up and immediately start using it like an expert. Telescopes have a learning curve, and some pointers from an experienced stargazer can greatly help jump-start your learning. Since amateur astronomers often hang out together and are usually eager to help others get started, search the Internet for “astronomy clubs” to find one near you. In our area, that would be the Central Texas Astronomical Society (www.centexastronomy).

If you have an opportunity, attend a public star party where amateur astronomers are likely to have a variety of types and sizes of scopes set up. They won't mind answering questions about their scope, and asking “How much did it cost?” is not considered impolite.

While there are several reputable brands of telescopes, Celestron and Meade being two of the most popular, anyone contemplating buying a scope might wish to request an Orion Telescope catalog – on-line at www.OrionTelescopes.com or by calling 800-676-1343. While I'm not recommending Orion or any other brand of scope – mine happens to be a Celestron – Orion's catalog gives a good idea of the wide array of telescopes, binoculars, and spotting scopes available – types, sizes, prices, and accessories.

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October 28, 2011
Stargazer #567

November 2011

This chart shows the night sky as appears on the 1st at 9 p.m., on the 15th at 8 p.m., and on the 30th at 7 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Nov. 1 – Sunrise: 7:44 a.m.; Sunset: 6:39 p.m. (Daylight Time) / Nov. 15 – Sunrise: 6:56 a.m.; Sunset: 5:29 p.m. (Standard Time) / Nov. 30 – Sunrise: 7:09 a.m.; Sunset: 5:25 p.m. (Times exact for Waco, TX)

• Moon
  Nov. 2: 1st Quarter / Nov. 10: Full / Nov. 18: 3rd Quarter / Nov. 25: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  Nov. 2 Wed. evening: The Moon is at 1st quarter.
  6 Sun., 2 a.m.: Set clocks back one hour to Standard Time.
  9 Wed. evening: Venus, Mercury, Antares are setting in west southwest 30 minutes after sunset as Jupiter and the nearly full Moon are rising in the east.
  11 Fri. morning: Mars is just to the left of the star Regulus high in the southeast and Saturn is to the upper left of the star Spica low in the east southeast.
  10 Thu.: The full Moon is called the Frosty Moon, the Beaver Moon, and the Snow Moon.
  14 Mon. evening: Mercury is at greatest eastern elongation 23º from the setting Sun.
  17 Thu. morning: The Leonid meteor shower peaks but the Moon, which rises after midnight, will interfere with the best meteor-viewing hours of morning.
  18 Fri. morning: The Moon is at 3rd quarter.
  18 & 19 Fri. & Sat. morning: The Moon passes by Mars and Regulus.
  22 Tue. morning: The crescent Moon is just to the right of Spica (nearest) and Saturn low in the east.
  25 Fri.: The new Moon produces a partial solar eclipse that won't be visible in our part of the world.
  26 Sat. early evening: Brilliant Venus and a thin crescent Moon are low in the west southwest with Mercury to their lower right.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Venus and Mercury (setting in west southwest), Jupiter (east)
  Mornings: Saturn (very low in east); Mars (east), Jupiter (low in west)
  * Mercury is near the west southwestern horizon at dusk, just below Venus, most of the month -- binoculars will help.
  * Venus is climbing higher daily, becoming the prominent “evening star” in the west.
  * Mars is up in the east well before sunrise.
  * Jupiter is well up in the east in the early evening and high in the west by morning.
  * Saturn is beginning to emerge from the glare of the rising Sun low in the east at dawn.
  

• Time Change Sun. Nov. 6, 2 a.m.: Before retiring Saturday night, set your clocks back (“fall back”) one hour to Standard Time.

• Constellation of the Month
  
  The constellation Pegasus the Winged (Flying) Horse is now high in the east in the evening sky. While it's difficult to visualize a horse, with or without wings, the well-known Square of Pegasus is distinctive and easily recognized. Four reasonably bright stars form an almost perfect square large enough that your fist, held at arm's length, will easily fit inside. (Your fist spans some 10 degrees while the square's sides extend nearly 15 degrees.)
  Jupiter, the brightest object in the east, is now well placed to assist in identifying the great square. Around 8 p.m., Jupiter is 30 degrees (three fist-widths) above the eastern horizon, and Pegasus is another three fists above Jupiter.
  Although called the Square of Pegasus, only three of the stars are in Pegasus. The square's brightest star, Alpheratz (lower left), is the brightest star in the constellation Andromeda the Princess. The stars extending upward from the square (see diagram) represent Pegasus' neck and head. Other than the great square, Pegasus has little to offer without the assistance of binoculars or a telescope.

• Pegasus in Greek Mythology
  
  With its ability to fly, Pegasus the Winged Horse had a prominent role in the rescue of Princess Andromeda by Perseus the Hero. Chained to a remote island, the beautiful princess was to be devoured by Cetus the Sea Monster as punishment for her mother's vanity. To save her, Perseus needed quick transportation, faster than any boat could take him, as well as a means for subduing the sea monster.
  To his good fortune, Athena, goddess of virginity, provided both. A beautiful woman named Medusa had been seduced by Poseidon, god of the seas, in Athena's temple. For desecrating her temple, Athena turned Medusa into a Gorgon, a dreadful creature with venomous snakes in place of her hair, and banished her to a cave. She was so hideous that all who gazed upon her were petrified with fear and turned to stone. Athena told Perseus to find Medusa, cut off her head, and show it to the sea monster who would turn to stone and sink into the sea.
  That solved the monster problem, but what about transportation? Well, Athena thought of everything. When Perseus severed Medusa's head, she being pregnant from her affair with Poseidon, out of her blood arose the fully grown winged horse. Perseus then rode Pegasus over the sea where, using Medusa's head, he dealt with the sea monster, and proceeded to the island where he rescued Andromeda, his wife-to-be.
  Pegasus, although a horse, was the offspring of Medusa, a mortal woman, and Poseidon, a god, thus he was partly mortal and partly divine. Following his service to Perseus, he was captured by another mythical hero, the mortal Bellerophon, and went on to other adventures, including the slaying of the people-eating Chimera, a creature with the head of a lion, the body of a goat, and the tail of a snake. (My those Greeks had morbid imaginations!)
  As seems so often with the powerful, Bellerophon's successes went to his head, and he foolishly decided to have Pegasus fly him to Mount Olympus, home of the gods. But since he wasn't a god, Zeus, the king of the gods, wouldn't allow it. He had Pegasus throw Bellerophon off whereupon he fell back to Earth. Pegasus, being partly divine, was permitted to enter the godly mountain where he spent his remaining days carrying Zeus' lightening bolts across the sky. For his faithful service, Zeus eventually placed Pegasus in the night sky where we see him to this day (night).
  Image: Bellerophon riding Pegasus the Winged Horse. Illustration by Mary Hamilton Frye in Hamilton Wright Mabie's Myths That Every Child Should Know (1914)

• Astro Milestones. Nov. 9 is the birthday of Carl Sagan (1934-1996), American astronomer, author, and co-founder of The Planetary Society. Nov. 20 is the birthday of Edwin Hubble (1889-1953), American astronomer for whom the Hubble Space Telescope is named.

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, Nov. 19, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 7 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, Nov. 12, 6-8 p.m. See www.centexastronomy.org for more information.

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October 14, 2011
Stargazer #566

Mystery Sighting

Sonya Moyer of Boyertown, PA, recently emailed me asking about a mysterious night sky sight she couldn't identify.

She wrote: "This morning around 5 a.m., I saw an amazing sight. I was sitting on my back porch facing southeast looking at the stars. A little above Orion a star just “swelled up” and seemed to burst! There were a few faint “sparks” that traveled up and to the right, then nothing – nothing where the star had been a moment before. I am sure of what I saw. Can you comment on this? Or you can just call me crazy, and I won't be offended. Sincerely, Sonya Moyer."

My response: "No, I don't think you're crazy. I'm guessing you happened to see a meteor coming directly in your direction before it broke apart and burned up. Meteors "falling" and burning up in our atmosphere are a common occurrence, and meteors breaking up before burning up, although less common, aren't rare. But, given that I've heard of so few reports, I'd say your experience is rare. In fact, I'm aware of only one other person who has shared your experience – ME – although I'm sure others must have as well.

"I had the same experience once while stargazing alone at a state park in far west Texas, only mine didn't explode – it just increased in brightness rather dramatically, and then rather quickly faded away. I was baffled until a fellow stargazer later proffered an explanation, and I realized that must have been what I had seen. In both our cases, the meteor might have been "natural" (a piece of stony or metallic meteoroid material) or human-made (a piece of satellite or rocket debris reentering and burning up in Earth's atmosphere).

"Given that one must be viewing in the right direction at the right moment from the right location on Earth to see what we saw, I'd say we were pretty lucky – and you were even luckier as your meteor broke up before disintegrating. Of course, we might be lucky in yet another way – had the meteor not completely burned up, and it was heading directly toward us... Thanks for sharing your experience."

Most people have seen meteors, also called “shooting stars” and “falling stars,” and stargazers who spend hours under the stars see countless meteors from the ordinary to those that make you gasp. And while seeing a meteor break up is far less common, it's not rare – I recall seeing three or four.

But seeing a meteor coming straight toward you – I would consider that pretty rare. And having a directly incoming meteor break up – extremely rare. I would like to hear from anyone who has seen either, or both simultaneously.

While meteors can usually be seen any clear night of the year and any time of night, seeing them still takes a bit of luck. One has to be looking in the right place at the right time, and they are usually so fleeting there's not time to point them out to a companion.

There are, however, ways of increasing the odds of seeing meteors. More will be seen under dark skies, away from urban light pollution, and when the Moon isn't up to wash out all but the brightest. And comfort is important. You'll probably want to stretch out on a blanket or reclining lawn chair as standing or sitting in an ordinary lawn chair can be tiring and will quickly make your back and neck ache. When that happens, you'll not want to watch long, reducing your chances of seeing meteors. When looking, slowly pan the skies in the direction with the least light pollution which is usually directly overhead. And while it's not convenient for us night owls, more meteors are visible in the morning than evening with the best hours being from midnight to dawn.

Finally, more meteors are apt to be seen during annual meteor showers, two of which occur this month. As Earth speeds around the Sun at 67,000 mph, it regularly passes through the debris-strewn paths of several comets. When some of the debris enters Earth's atmosphere, friction causes it to burn and momentarily glow brilliantly as meteors in our night sky.

Image: All-sky fish-eye 4-hour exposure of the Leonid meteor shower November 17, 1998.
Most of the 156 meteors captured in this image seem to radiate from the constellation Leo the Lion, hence the name.
Credit: Juraj Toth at Modra Observatory in Slovakia, posted on Wikimedia Commons.

The following are the major annual meteor showers and when they usually peak. Dates are approximate since cometary debris drifts somewhat in space, making it difficult to predict the exact timing of Earth's passage through the maximum debris stream. Thus, it's best to be alert for increased meteor activity for several days around each stated date. Quadrantid – Jan. 4 / Lyrids – Apr. 22 / Eta Aquarids – May 6 / Delta Aquarids – Jul. 30 / Perseids – Aug. 13 / Draconids – Oct. 8 / Orionids – Oct. 21 / Taurids – Nov. 12 / Leonids – Nov. 17 / Geminids – Dec. 14 / Ursids – Dec. 14

So in summary, one is more likely to see meteors away from urban lights under dark, moonless skies, after midnight, and during meteor showers. And who knows, like Sonya, you just might see one breaking up while coming directly toward you.

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September 23, 2011
Stargazer #565

October 2011

This chart shows the night sky as appears on the 1st at 10 p.m., on the 15th at 9 p.m., and on the 31th at 8 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Oct. 1 – Sunrise: 7:22 a.m.; Sunset: 7:14 p.m. / Oct. 15 – Sunrise: 7:32 a.m.; Sunset: 6:57 p.m. / Oct. 31 – Sunrise: 7:44 a.m.; Sunset: 6:40 p.m. (exact for Waco, TX)

• Moon
  Oct. 3: 1st Quarter / Oct. 11: Full / Oct. 19: 3rd Quarter / Oct. 26: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  Oct. 3 Mon. evening: The Moon is at 1st quarter.
  8 Sat. all night: The Draconid (Giacobinid) meteor shower peaks but the nearly full Moon will wash out all but the brightest meteors.
  11 Tue.: The full Moon is called the Hunter’s Moon and the Dying Grass Moon.
  19 Wed. morning: The Moon is at 3rd quarter.
  21 Fri. morning: The Orionid meteor shower peaks tonight with the best views likely to come before the Moon rises in the wee hours of morning.
  26 Wed.: The Moon is new.
  27 Thu. early evening: A thin crescent Moon (bottom), Mercury, and Venus (top) are aligned vertically just above the western horizon after sunset.
  28 Fri.: Jupiter is at opposition – opposite the Sun as seen from Earth – when it rises at sunset, is up all night, and sets at sunrise.
  31 Mon.: Halloween, a cross-quarter day celebrating the middle of fall.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Venus (setting low in west), Jupiter (rising in the east), Mercury (west, late in month)
  Mornings: Mars (east), Jupiter (east), Mercury (early in month)
  * Mercury emerges low in the west late in the month.
  * Venus is climbing higher daily, becoming the prominent “evening star” in the west. * Mars is up in the east well before sunrise.
  * Jupiter rises in the early evening and is high in the west by morning.
  * Saturn is now hidden in the Sun's glare.
  

• Constellation of the Month
  
  Lyra the Musical Lyre is a small constellation just to the west of Cygnus the Swan and the Milky Way. Being rather northerly, it is visible in our evening skies over half the year, from June through December. While it may not look like a musical instrument, its shape is distinctive – a parallelogram hanging from an especially bright star, 1st-magnitude Vega, the fifth brightest star in the night sky.
  It's hard to miss Vega, being the most brilliant object nearly straight overhead in the early evenings of fall. Situated 25 light years away, Vega was made famous in the movie “Contact” based on Carl Sagan's novel. In the story a radio astronomer, played by Jodi Foster, discovered a radio message from intelligent beings seemingly coming from Vega.
  Vega also combines with the brightest stars of two other constellations, Deneb (in Cygnus the Swan) and Altair (in Aquila the Eagle), to form the large Milky Way Triangle (also known as the Summer Triangle) now high overhead.
  In addition to Vega, Lyra also contains other jewels, two of which are Epsilon Lyri and the Ring Nebula. Epsilon Lyri looks like a rather ordinary star a finger-width (held at arm's length) from Vega which binoculars show to be a double star. But that isn't the whole story as a telescope at high power reveals each of those stars to be a double star, hence the star's nickname, the Double-Double. These four stars, along with a couple of even fainter ones, form a multiple star system in which all the stars are gravitationally bound and orbit a common “center of gravity.”
  The Ring Nebula, also known as M57, is one of the most popular and well-known planetary nebula. The term is misleading as it has nothing to do with planets; rather it is the visible remnant of dead star. Through a telescope M57 looks like a tiny, faint greyish donut-shaped cloud while astrophotography displays its rich colors. Unseen at the center is a small, Earth-sized dead star called a white dwarf, the hot and still-glowing “corpse” of a giant star that died less than 2,000 years ago at a distance of 2,300 light-years. The visible cloud is the star's outer shell of gasses that were blow away during the star's last gasp of stellar life. The Ring Nebula gives a preview of what our Sun will look like when it dies in 5-6 billion years.

  Images: Lyra (Scott Roy Atwood) / Epsilon Lyri (Astrokay's Website) / Ring Nebula (Meyer Observatory, Central Texas Astronomical Society)

• Lyra in Greek Mythology
  
  Lyra is one of the 48 constellations from antiquity. In Greek mythology the harp-like stringed instrument belonged to Orpheus, the superbly gifted minstrel whose music and voice could charm people, tame wild animals and even change the flow of rivers. It was given to Orpheus by the god Apollo who taught him to play with the power of a god. Like Willie Nelson and his guitar, Orpheus and Lyra were widely traveled. They accompanied Jason and the Argonauts on their quest for the Golden Fleece, and saved the ship and crew from certain shipwreck by drowning out the sinister singing of the seductive Sirens with powerfully beautiful music.
  But alas, his life ended prematurely. His wife, the beautiful nymph Eurydice, died when bitten by a snake. Orpheus was so grief-stricken that, with lyre in hand, he climbed down into the Underworld to retrieve Eurydice. His music had such power that even Hades (Pluto) agreed to allow her to accompany him back to Earth – on the condition that Orpheus would refrain from casting his gaze upon her until they were completely out of the Underworld. Unfortunately, just before reaching Earth's surface, he couldn't resist glancing back to make sure she was still with him, and when he did, she immediately vanished and returned once again to the Land of the Dead.
  The grief of losing his lovely young wife, not once but twice, was more than he could bear. Thereafter he forsook the company of all women, causing the wild women of Thrace, out of jealousy, to kill him. They threw his lyre into the river as Orpheus himself descended into the Underworld to spend eternity with his beloved wife, Eurydice.
  Zeus, the king of the Gods, had Aquila the Eagle retrieve Orpheus' lyre from the river and carry it into the sky where Lyra continues making music for the whole world to enjoy.
  Image: Orpheus and Lyra charming the wild animals with music. Credit: An ancient Roman floor mosaic now in the Archeological Museum of Palermo, photographed by Giovanni Dall'Orto in 2006.

• Astro Milestone. Oct. 4, 1957, the Russian's launched Sputnik I, the first human-made Earth-orbiting satellite, beginning of the Space Age. Oct. 29 is the birthday of Edmund Halley (1656-1742), English astronomer of Halley's Comet fame.

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, Oct. 22, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 7 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, Oct. 8, 7-9 p.m. See www.centexastronomy.org for more information.

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September 9, 2011
Stargazer #564

Comet Elenin and Other Fables

With my BA, MSW, and PhD degrees in the behavioral sciences, one would think I should have greater insight into a certain perplexing human behavior, one that overlaps with my avocational field of astronomy. In the two decades I've been writing “Stargazer” and presenting astronomy programs, I've been asked numerous times about “threats” to us and our planet, mostly relating to things from outer space. And though I do my best to allay such fears, some continue to accept uncritically what they read on the Internet.

One of the latest is Comet Elenin which, according to various Internet stories, might not be a comet at all but rather a “rogue planet” larger than Jupiter, or maybe a brown dwarf star which has entered our solar system. And it's going to rain all kinds of havoc on us Sept. 26, 2011 – or is October, or maybe November, or sometime in 2012? Depends on which crackpot you read.

Some claim it might crash into Earth. Others say even if misses, its gravitational pull will cause devastating earthquakes and tsunamis. And if that doesn't happen, then its powerful magnetic force will bring about changes in Earth's tilt, and perhaps even cause a pole shift. And why aren't we reading more about this in the mainstream media? Because there is a government conspiracy to keep it hushed lest the masses (that's us) panic.

Image: Comet Elenin as imaged by NASA's STEREO spacecraft Aug. 6, 2011

Wow, that's a lot of worry about Comet Elenin which is, in fact, a small chunk of rocky ice less than 3 miles in diameter that will pass 21 million miles from Earth Oct. 16. The worry is all the more remarkable given the fact that Venus, which is close to Earth's size, regularly passes nearly that close to us, and nothing happens – no earthquakes, no tsunamis, no pole shifts – nothing beyond giving us a beautiful “evening star” or “morning star.”

Elenin is just the most recent of such fables. Perhaps you've heard of Nibiru, Planet X, the aliens who crash-landed near Roswell, NM, or the 2012 Maya prophecy, to name but a few. And while I find no credible evidence to support any of these, I recognize that such stories hold a certain fascination – even for me.

As a teenage in the 1950s, I was captivated by amateur hypnotist Morey Bernstein's book The Search for Bridey Murphy, about the woman who under hypnotism was “proving” the existence of reincarnation by revealing information from her supposed previous lives. And there were the countless UFO “sightings” reported in the news that always made my ears perk up.

Then in the 1970s I was attracted to Erich Von Daniken's books, especially Chariots of the Gods? in which he set out to prove that many seemingly mysterious occurrences were the work of ancient astronauts thousands of years ago. But as much as I wanted to believe these things, they simply didn't hold up to critical scrutiny.

Most of the Internet-based fantasies in recent years seem to deal with threats to us and our planet – asteroids, comets, rogue planets or whatever on paths to destroy poor, hapless and helpless us.

That's not to say there is no chance of a large space object impacting Earth – it's happened many times before in Earth's history, and will certainly happen again, although probably not in our lifetime. There are efforts underway to find and track all near Earth objects (NEOs) that might pose a threat to Earth; to date none have been found that justify seriously worry. If and when any are found, it is unlikely our government, or any other, would try to keep it secret, or be able to if it tried.

Even though these Internet-fostered imagined threats can almost always be easily dispelled by scientific evidence, they still attract some folks like iron to a magnet. Many seem to want so strongly to believe them that no evidence can budge their thinking, and my behavioral scientist self has trouble coming up with a satisfactory answer to “Why?”

Perhaps these stories simply entertain us, just as we're entertained by novels, movies, and science fiction – even when we know the stories aren't true. But that seems only a partial answer; it doesn't explain why many people apparently really want to, and do, believe these fictions.

If they are attracted by ideas of drastic and dramatic threats to us and our planet, they need look no further than the many real threats we face, like our endless wars, or the tragic maldistribution of wealth, or our species' role in global warming, or our overpopulating, trashing, and depleting the finite resources of our planet. These are real horror stories, so why aren't there more Internet warnings about things that are truly threats to our well-being and survival. Why does there seem to be so much denial about these dangers?

Ah! Denial. Maybe that explains the curious behavior of our gullibility to fanciful dangers. Perhaps by dreaming up and preoccupying our thoughts with imagined threats, which deep in our subconscious we know or strongly suspect aren't real, it makes it easier to ignore those threats which, deep in our subconscious, we fear are real and which scare the living daylights out of us.

Maybe this explains our curious behavior, or maybe it doesn't, but there's no denying we'd be better off applying our mental energies and other resources to thinking about and dealing with real perils rather than imagined ones. That, of course, is a no-brainer, but how to make that happen – well, that's something else again. And while my college degrees still don't give me the satisfying answers I'd like, they helped me learn to think critically and inoculated me from the gullibility and magical thinking that afflict so many of our fellow sojourners on planet Earth.

Late bulletin: Comet Elenin may be disintegrating after being blasted by a solar flare and coronal mass ejection from the Sun in late August.

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August 26, 2011
Stargazer #563

September 2011

This chart shows the night sky as appears on the 1st at 10:30 p.m., on the 15th at 9:30 p.m., and on the 30th at 8:30 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Sep. 1 – Sunrise: 7:04 a.m.; Sunset: 7:52 p.m. / Sep. 15 – Sunrise: 7:13 a.m.; Sunset: 7:34 p.m. / Sep. 30 – Sunrise: 7:22 a.m.; Sunset: 7:15 p.m. (exact for Waco, TX)

• Moon
  Sep. 4: 1st Quarter / Sep. 12: Full / Sep. 20: 3rd Quarter / Sep. 27: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  Note: September is a good month to see the zodiacal light in the morning.
  4 Sun. evening: The Moon is at 1st quarter.
  12 Mon.: The full Moon is called the Harvest Moon, Fruit Moon, and Corn Moon.
  16 Fri. morning: Bright Jupiter is to the left of the much brighter waning gibbous Moon in the west southwest, and the next morning is below the Moon.
  20 Tue. morning: The Moon is at 3rd quarter.
  23 Fri. morning: Mars is to the upper left of the crescent Moon low in the east.
  23 Fri.: Autumn equinox – the beginning of fall in the Northern Hemisphere when night and day are of approximately equal length. 27 Tue.: The Moon is new.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Saturn (early evening, setting in west), Jupiter (late evening, rising in east)
  Mornings: Mars, Jupiter (east), Mercury (early in month)
  * Mercury is low in the east early in the month., spending most of August hidden in the Sun's glare, begins to emerge in low in the E at dawn by month's end.
  * Venus is still hidden the glare of glare of the Sun.
  * Mars is up in the east well before sunrise.
  * Jupiter rises in the late evening and is high in the south by morning.
  * Saturn, very low in the west in the early evening at the beginning of the month, is all but lost in the Sun's glare by month's end.
  

• Constellation of the Month
  Cygnus the Swan, being a rather northerly constellation, is visible in our evening skies over half the year, from June through December. With a little imagination, one can actually visualize a long-necked swan with wings spread wide gracefully flying southward along the Milky Way.
  Cygnus has one bright 1st-magnitude star, Deneb, which represents the swan's tail. Its head (actually beak) is a fainter but special star named Albireo. Those two plus three other central stars form an informal pattern (called an asterism) known as the Northern Cross with Deneb at the top and Albireo at the bottom.
  Deneb also combines with the brightest stars of two other constellations, Vega (in Lyra the Lyre) and Altair (in Aquila the Eagle), to form the large Milky Way Triangle (also known as the Summer Triangle), currently seen high overhead.
  There are several myths related to Cygnus dating back at least to the Greeks. In the most commonly told story, Zeus (Jupiter), the king of the gods, had the hots for the beautiful but human Leda., wife of a local king. (It made no matter to Zeus that both were married as he had the hots for many women – mortal and immortal – and fathered more children than Genghis Khan.) To seduce Leda, he disguised himself as a handsome swan; among their demigod (half-god, half-human) offspring were Helen of Troy and the Gemini twins, Pollux and Castor.
  In my favorite story, a minor Greek god named Cygnus and the mortal Phaeton were close friends who liked to compete with each other as young lads often do. Once they decided to race through the sky to the Sun and back. Unfortunately, they rounded the Sun too closely and their chariots were burned, causing both to fall back to Earth. When Cygnus regained consciousness, he set out to find his buddy. Sadly, he found that the dead body of Phaeton was entangled in roots at the bottom of the River Eridanus. When he tried to retrieve his friend's body for burial, he was unable to dive deep enough, and while grieving on the river's bank, called out for help from Zeus. The king of the gods offered to turn him into a swan whereby he could dive deeply enough to reach Phaeton's body – but it would come at a price: he would have to give up his immortality and remain a moral swan until he died. Cygnus agreed to the terms, recovered his friend's body, and gave him a proper burial so his spirit could move on to the afterlife. When Cygnus eventually died, Zeus placed him in the night sky to honor him for his unselfish loyalty to his friend.

  Diagram by the author. / Illustration – Cygnus as depicted in Urania's Mirror, a set of constellation cards published in London c.1825.

• Star of the Month
  Albireo, the star representing Cygnus the Swan's head or beak, is more than meets the eye. Located 380 light-years away, to naked eyes and even through most binoculars, Albireo is an ordinary-looking 3rd-magnitude star, fainter even than the stars forming the Big Dipper. But seen through a telescope, even at low power, it will knock your socks off. It is a breathtaking double star – a bright golden yellow star with a fainter pastel blue companion – considered by many, including myself, to be the most beautiful of all double stars. The two stars may be a binary star system, bound gravitationally and orbiting each other, but if so they are widely separated and take 75,000 years to complete one orbit. [Photo: Wikimedia Commons]

• Astro Milestone. September 23, 1846, astronomers Johann Galle & Heimrich d'Arrest discovered the planet Neptune from Germany's Berlin Observatory. Their discovery was made based on the predictions and position-calculations of Urbain Jean Joseph Leverrier of France.

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, Sep. 17, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 7:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, Sep. 10, from 7-9 p.m. See www.centexastronomy.org for more information.

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August 12, 2011
Stargazer #562

Constellations

When we peer into the night sky we see stars, planets, the Moon, meteors and other beautiful heavenly bodies. And with a little imagination, we can also “see” a variety of animate and inanimate objects as constellations formed by imaginary lines between some of the brighter stars.

The practice of creating imaginary figures from the stars goes back unknown thousands of years, and has likely been done by many, if not most, peoples of the world. What was seen, of course, reflected the life and experiences of those whose imaginations made them up. Where the Greeks saw a hunter, the Maya saw a Maize God-bearing turtle and the hearthstones of creation. And for all we know, Africans might have seen a zebra, South Americans a snake, Asians a temple, or Australians a kangaroo.

Left image: Orion the Hunter as seen by the Greeks (illustration: Urania's Mirror, London, c. 1825). Right diagram: In the same star field, the Maya saw the Three Hearthstones and Turtle of Creation (illustration: Maya Cosmos, David Freidel, Linda Schele & Joy Parker, 1993)

Since 1930, the International Astronomical Union has recognized 88 official constellations, 48 of which come from antiquity. Some likely came from the Sumerians who might have handed them down to the Babylonians, who, in turn, bequeathed them to the Greeks., and eventually to us. And who knows what sky lore and knowledge the Sumerians might have inherited from their ancestors. Since these civilizations lived in the Northern Hemisphere, the constellations they invented were only in the parts of the night sky they could see.

The remainder of today's constellations, mostly those seen from deep within the Southern Hemisphere, were created by Europeans when they began exploring previously unknown (to them) parts of the world. When they saw new stars, they invented European-oriented constellations, like a telescope, microscope, compass, and clock.

How I wish they had been less ethnocentric and inquired of the indigenous populations they encountered what they saw in the sky. Our knowledge of this aspect of other ancient cultures, including Native Americans, is quite limited. Imagine how much richer our night sky lore and imagery would be if we also knew how others from around the world had seen the night sky.

Even so, no one with any imagination should find the night sky boring as it is filled with people, animals, mythical creatures, and inanimate objects. Among the people are Andromeda the Princess, Aquarius the Water Carrier, Auriga the Charioteer, Bootes the Herdsman, Cassiopeia the Queen, Cepheus the King, Gemini the Twins (Pollux and Castor), Hercules the Strongman, Indus the American Indian, Ophiuchus the Serpent Bearer, Orion the Hunter, Perseus the Hero, and Virgo the Virgin.

Non-human animals include many kinds of birds, several dogs and fish, three snakes, two lions, two bears, a ram, giraffe, crab, chameleon, dolphin, lizard, rabbit, wolf, lynx, scorpion, bull, colt, fox, and even a fly. Mythical critters include two centaurs, a dragon, seagoat, unicorn, sea monster, and a flying horse.

The plethora of inanimate objects could make for the mother of all garage sales. They include an air pump, alter, engraving tool, drawing compasses, two crowns, cup, cross, furnace, clock, scales, musical lyre, microscope, carpenter's square, octant, painter's easel, mariner's compass, reticle, arrow, sculptor's tool, shield, sextant, telescope, and two triangles. And if that's not enough, there's the long beautiful hair of Queen Berenices, several parts of the great ship Argo on which Jason and the Argonauts had their adventures, and a river and a mountain.

With that much company, how could anyone ever be lonesome or bored under the night sky. But if that's not enough, I encourage you to create your own constellations. Surely you can be just as creative as the Greeks, Babylonians, Sumerians, and others of yesteryear.

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July 29, 2011
Stargazer #561

August 2011

This chart shows the night sky as appears on the 1st at 11 p.m., on the 15th at 10 p.m., and on the 31th at 9 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  Aug. 1 – Sunrise: 6:45 a.m.; Sunset: 8:25 p.m. / Aug. 15 – Sunrise: 6:54 a.m.; Sunset: 8:12 p.m. / Aug. 31 – Sunrise: 7:04 a.m.; Sunset: 7:54 p.m. (excact for Waco, TX)

• Moon
  Aug. 6: 1st Quarter / Aug. 13: Full / Aug. 21: 3rd Quarter / Aug. 28: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  Note: August and September are the best times to see the zodiacal light in the morning.
  1 Mon.: Lammas, a cross-quarter day celebrating the middle of summer.
  1 Mon. evening: The crescent Moon is to the upper left of Mercury near the western horizon at dusk.
  3 Wed. evening: The Moon is below Saturn low in the southwest, and to the ringed planet's left the next night.
  6 Sat. evening: The Moon is at 1st quarter.
  13 Sat.: The Perseid meteor shower peaks, but the full Moon makes this an unfavorable year for this popular shower.
  13 Sat.: The full Moon is called the Grain Moon and Green Corn Moon.
  20 Sat. morning: The gibbous Moon is above Jupiter high in the southeast.
  21 Sun. morning: The Moon is at 3rd quarter.
  25 Thu. morning: A thin crescent Moon is just to the left of Mars in the east.
  28 Sun.: The Moon is new.
  31 Wed. evening: The crescent Moon (below), Saturn (upper right), and the star Spica (upper left) form a triangle low in the west at dusk.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Saturn (low in W)
  Mornings: Mars, Jupiter (E)
  * Mercury, spending most of August hidden in the Sun's glare, begins to emerge in low in the E at dawn by month's end.
  * Venus spends the month hiding in the glare of glare of the Sun.
  * Mars is up well before the Sun, but still low in the eastern morning sky.
  * Jupiter rises around midnight and is high in the ESE by morning.
  * Saturn, seen low in the W in the early evening and down before midnight, is edging nearer the setting Sun.
  

• Constellation of the Month
  Sagittarius, a constellation deep in the southern sky, has something in common with Ursa Major in the northern sky. Both are more easily identified by an informal pattern of stars within the larger constellation. Ursa Major the Big Bear takes a good imagination to see a bear in the stars, however most people have no difficulty seeing the Big Dipper, an informal pattern (called an asterism) formed by the brighter stars of Ursa Major.
  And while Sagittarius the Archer doesn't look much like anyone shooting a bow and arrow, it doesn't take much imagination to see a large teapot embedded within its stars. And, if you're fortunate enough to view it under dark skies, an unusually rich part of the Milky Way galaxy seems to be steam rising from the teapot's spout. Pretty neat.
  In Greek mythology, Sagittarius is a centaur archer – a centaur being part human (front) and part horse (rear). The human component – a man from the waist up – is aiming an arrow at the heart of nearby Scorpius the Scorpion. But perhaps the scorpion needn't worry too much as the centaur may not be such a good shot. The constellation Sagitta the Arrow, one of Sagittarius' earlier shots, is seen whizzing past, but missing, nearby Vulpecula the Fox.
  Sagittarius contains no bright 1st-magnitude stars yet it is seen against one of the richest parts of the night sky. The center of our Milky Way galaxy is near the spout of the teapot asterism, and while we can't actually see into the heart of the galaxy, we do see an extremely star-dense area that includes many star clusters and nebulae.
  Sagittarius is a familiar constellations that most people have heard of, even if they can't identify it in the night sky. Being on the ecliptic – the path of the Sun, Moon, and planets across the sky – it is a constellation in astrology's zodiac and represents one of the twelve “signs” for those who are into this popular system of superstition. Being on the ecliptic, Sagittarius is frequently seen being visited by the Moon and planets passing near the top of the teapot pattern.

• Dawn at Vesta.
  In July, NASA's Spacecraft Dawn arrived at and began orbiting Vesta, the third largest member of the Asteroid Belt circling the Sun between the orbits of Mars and Jupiter, and in early August begins studying the tiny world. Launched Sept. 27, 2007, Dawn will spend a year gathering data about Vesta after which it will begin phase two of its mission. In July 2012, it will fire its ion thruster engine, leave Vesta, and begin a 3-year journey to Ceres, the largest of the Asteroid Belt's members.
  So why study both? Vesta, some 335 miles in diameter, has some intriguing differences in composition and other characteristics from Ceres, some 600 miles in diameter. Both are believed to be little changed since their formation during the infancy of our solar system, thus studying them should enable scientists to learn more about the birth and evolution of our Sun and its solar system members. Since 1995, we have been finding many planets around other stars, suggesting that many, if not most, stars have solar systems. So by extension, Dawn will likely contribute to our understanding of the formation of these other solar systems throughout our Milky Way, and presumably the countless billions of solar systems in the other galaxies throughout the cosmos. Pretty lofty goals for such a small spacecraft with such a charming name. To learn more about Dawn and its mission see www.dawn.jpl.nasa.gov/.
  [Image: Artist's conception of Spacecraft Dawn gathering data at Vesta. Credit: NASA/McREL]
  

• Total Solar Eclipse Early Notice. It is only six years until the Aug. 21, 2017, when the 70-mile wide shadow of a total solar passes across the middle of the U.S. from Oregon to South Carolina. Better start making your travel plans.

• Astro Milestone. August 1 is the birthday of Maria Mitchell (1818-1889), America's first woman astronomer.

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, Aug. 20, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 8 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, Aug. 13, from 8-10 p.m. See www.centexastronomy.org for more information.

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July 8, 2011
Stargazer #560

Seeing Is Believing...or Is It?

Have you seen this beautiful image? Captioned “Sunset at the North Pole,” it's been getting email mileage on the Internet for several years. I saw it again last month when a friend forwarded it to me.

According to the accompanying text, “This is one of the rarest pictures that you will ever see in your life when the moon was closest to the Earth. The date the picture was taken was Thursday, 13th May, 2011. This is the sunset at the North Pole with the moon at its closest point. A scene you will probably never get to see in person, so take a moment and enjoy. And, you also see the sun below the moon, an amazing photo and not one easily duplicated.”

The author of the text was purported to be a “lecturer of library and information science” affiliated with two prominent universities. But as pretty as the image is and as authoritative as the source might sound, it is simply another of the countless Internet hoaxes. Remember when Mars was supposed to look as large as a full Moon?

There are so many problems with this North Pole sunset email it's hard to know where to begin debunking it. For starters, May 13, 2011, was a Friday, not Thursday, but that's being picky.

More substantive is the fact that the photo shows the Moon at or very near the new Moon, when the Moon passes between Earth and the Sun. The Moon was new Tuesday, May 3, so maybe the lecturer meant May 3 rather than May 13?

But there's a problem with May 3. If the Moon was “closest to Earth” as claimed, then the photo had to have been taken May 16 when the Moon was at perigee, the point in its monthly elliptical orbit when it swings nearest Earth. And at perigee, the Moon does actually appear larger than average – although only slightly.

There's an even bigger problem with May 16 as the Moon wasn't even visible from the North Pole when it was nearest Earth at perigee. It dipped below the horizon May 12, quite some distance from the Sun, and didn't reappear until May 26, thus no one could have even seen, much photographed, it May 13 or 16 from the North Pole.

And for yet another stake in the heart of this Internet hoax, from the March equinox to September equinox, there is no “sunset at the North Pole.” In this “land of the midnight Sun,” the Sun is constantly in the sky day and night without rising or setting for half a year. In May it hovers some 18 degrees above the horizon as it circles the horizon each day.

Regarding their relative sizes, the Moon and Sun always appear virtually the same size – about ½ degree, a space easily covered with the end of a finger held at arm's length. (This derives from the fact that the Sun is 400 times more distant than the Moon and, by coincidence, 400 times larger.) And while the apparent relative sizes of the Sun and Moon do vary, owing to the Earth's elliptical orbit around the Sun and the Moon's elliptical orbit around Earth, the variance is slight and barely noticeable to the casual observer.

All questionable dates and other factors aside, never at any time or season or from any location on Earth does the Moon appear notably larger (or smaller) than the Sun, and certainly not some 40 times larger as this image indicates.

So, maybe seeing isn't always believing after all. Such hoaxes do, however, serve a purpose: they remind of the importance of maintaining a healthy degree of skepticism and keeping our skills of critical inquiry ever at the ready, whether watching TV or reading emails, newspapers, or even this column.

The Web site snopes.com is an excellent source for checking the accuracy of Internet claims. It's usually the first place I turn when anything pushes my skepticism button. According to snopes, this "photograph" is believed to be a digital image entitled "Hideaway" created by Inga Nielsen, a German astrophysics student using Terragen scenery rendering software. There is no indication that Nielsen perpetrated this hoax; more likely, someone else misused the creative artwork.

[Note: Thanks to Mary Jane Ford of Austin, TX for the idea for this column.]

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June 24, 2011
Stargazer #559

July 2011

This chart shows the night sky as appears July 1 at 11:30 p.m., July 15 at 10:30 p.m., and July 31 at 9:30 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  July 1 – Sunrise: 6:27 a.m.; Sunset: 8:37 p.m. / July 15 – Sunrise: 6:34 a.m.; Sunset: 8:35 p.m. / July 31 – Sunrise: 6:44 a.m.; Sunset: 8:25 p.m. (exact for Waco, TX)

• Moon
  July 1: New / July 8: 1st Quarter / July 15: Full / July 23: 3rd Quarter / July 30: New

• Night Sky Events [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  July 1 Fri.: The Moon is new produces a partial solar eclipse that won’t be visible in the U.S.
  2 Sat. evening: The crescent Moon is 6º to the lower left of Mercury near the WNW horizon soon after sunset.
  5 Tue. morning: Mars is 5º to the upper left of the slightly brighter star Aldebaran very low in the ENE at dawn.
  7 Thu. evening: The Moon is 8º to the lower left of Saturn in the WSW.
  8 Fri. evening: The Moon is at 1st quarter.
  12 Tue.: Neptune completes its first orbit of the Sun since it was discovered in 1846; one Neptunian year equals nearly 165 Earth years.
  15 Fri.: The full Moon is called Hay Moon and Thunder Moon.
  20 Wed. evening: Mercury is at greatest elongation 27º east of the setting Sun.
  23 Sat. morning: The 3rd quarter Moon is 8º to the left of Jupiter.
  27 Wed. morning: The crescent Moon is 3º to the upper right of Mars low in the ENE.
  30 Sat. morning: The Delta Aquarid meteor shower peaks with no Moon interference.
  30 Sat.: The Moon is new, for the second time this month.
  

• Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Mercury (W, very low), Saturn (SW)
  Mornings: Venus, Mars, Jupiter (all in the E)
  * Mercury, spending most of July low in the west in the early evening, appears highest above the setting Sun around mid-month.
  * Venus, ending this year's stint as the "morning star," rises only an hour before the Sun early in the month and is virtually lost in the Sun's glare by month's end.
  * Mars is rising well before the Sun and is daily climbing higher in the eastern morning sky.
  * Jupiter rises several hours before sunrise and is easily the brightest object in the eastern sky before dawn.
  * Saturn well up in the southwest in the evening sky, will soon be setting by midnight.
  

• Constellation of the Month
  Scorpius the Scorpion is one of the few constellations that actually look somewhat like what they are supposed to represent in the night sky. Facing south soon after dark, look for a large fish-hook shaped pattern fairly low with a bright reddish star at the upper right end. That red star, Antares, is the scorpion’s head; the stars to its upper right are its pinchers. Its body winds downward to the left before curling up to form the tail; at the end of the tail are two close stars, the brighter of which is Shaula, the scorpion’s stinger. If you're fortunate enough be viewing from dark skies, note that Scorpius is seen against the glow of the Milky Way which is rising from the horizon toward the upper left.
  In Greek mythology it was the duty of Scorpius to sting and kill Orion the Hunter who had offended one of the gods with his overly macho behavior. Another of the gods friendly to Orion in return killed Scorpius. Both were then placed in the sky by their respective guardian gods. But in a moment of rationality, the gods agreed they didn't want Orion and Scorpius fighting throughout eternity, so Orion was placed in the winter sky and Scorpius in the summer sky. As the Greek philosopher-poet Aratos of Soloi (c. 310 - 245 BCE) wrote, “When the Scorpion come, Orion flies to the utmost end of earth,” thus they are never in the sky at the same time. (Humm...that might be a strategy worth considering here on Earth. Let's see, would the Democrats or the Republicans get the summer or winter?)

• Antares, not Mars
  Antares, the bright reddish star representing the head of Scorpius the Scorpion, is a red giant nearing the end of its life. Situated 600 light years away, Antares is vastly larger than our Sun, weighing in at 15-18 solar masses. Its diameter of 800 Suns means Antares, if it was at the center of our solar system, would swallow the four innermost solid planets – Mercury, Venus, Earth, and Mars – leaving only the four gas giants – Jupiter, Saturn, Uranus, and Neptune. When our Sun nears the end of its life, as all stars eventually do, it will expand and consume the inner three planets – and yes, that includes us. But since we're talking 5 billion or so years down the road, don't quit school or cash in your IRA.
  According to most interpretations, the star's name comes from ancient Greece and means “not Ares,” “rival of Ares,” or “anti-Ares,” referring to Ares, the Greek god of war. (When the Romans later adopted Greek religion, the god of war was renamed Mars.) Since Antares is situated on the ecliptic – the path of the Sun, Moon and planets – the planet Mars regularly passes near Antares, and as they appear similar in brightness and color, the name makes sense to avoid confusing not-Mars with the real Mars.

• Year Half Over. The midpoint of the year occurs July 2 at noon, local standard time.

• Farthest from Sun. July 4 Earth is at aphelion, its farthest point from the Sun in its elliptical orbit. With an average distance of 93 million miles, the July distance of 94.5 million miles is 3.4% more distant than when Earth is perihelion, its nearest point to the Sun, in early January. (In case you're wondering, that small variation has very little effect on Earth's surface temperature.)

• Astro Milestone. July 20 is the 42nd anniversary of the 1969 Moon landing, when American astronauts Neil Armstrong and Buzz Aldrin became the first humans to land and walk on the moon.
  [NASA photo: Astronaut Neil Armstrong photographs Astronaut Buzz Aldrin as Aldrin becomes the second human to set foot on the Moon -- second only to Armstrong.]
  

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, July 23, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 8:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, July 9, from 8-10 p.m. See www.centexastronomy.org for more information.

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June 10, 2011
Stargazer #558

Summer Solstice - the Sun Goes North for the Summer

It's almost time for the June 21 summer solstice, the beginning of the summer season and longest day of the year in the Northern Hemisphere.

Solstice, meaning “Sun stand still,” occurs twice each year – at the summer and winter solstices – and was noted and named long ago by the ancients. Of course, the Sun doesn't really stop moving across our sky; the “stand still” refers to the locations on the horizon where the Sun rises and sets.

We are told that each day the Sun rises in the east and sets in the west due to the Earth's daily west-to-east rotation on its axis, and that's generally true. And it true not just for the Sun but for virtually all the natural sky objects, including the Moon, planets, and stars, which move in a broadly easterly-to-westerly direction across our sky, day and night. (About the only exceptions are rapidly moving meteors and circumpolar stars when they are lower than Polaris – a topic for another column.)

Back to the Sun. Actually, only at the fall and spring equinoxes does it rise exactly due east and set exactly due west. After the spring equinox the Sun then sets ever-so-slightly further north of west each evening, and rises ever-so-slightly further north of east each morning – and the days become slightly longer – until the summer solstice when it stops its northward movement.

It then seems to “stand still” for a few days – rise at the same location on the eastern horizon and set at the same location on the western horizon – before reversing direction and retracing its steps to again rise in the east and set in the west at the fall equinox. After the fall equinox it continues its southward movement, rising slightly further south of east and setting slightly further south of west – with the days growing shorter – until it reaches winter solstice. And the annual cycle continues.

How far north and south of due west the Sun sets (and rises in the east) at the solstice varies with latitude (expressed as degrees above the equator, or below the equator in the Southern Hemisphere). At the equator (latitude 0°), the Sun rises and sets 23½ degrees from due east and west at the solstices, owing to the Earth's 23½-degree tilt on its axis. The further from the equator, the greater the differences become. (For example, here in Waco, TX, at latitude 31.5° N, the solstice Sun sets 28 degrees north of due west, and in Fargo, ND, nearly 37 degrees north of west.)

Similarly, the lengths of days and nights throughout the year also vary by latitude. At the equator, days and nights are each 12 hours in length throughout the year, including at the solstices. But this changes as latitude increases.

At summer solstice, the year's longest day in Guatemala (15° N) lasts 13 hours while in Waco we have over 14 hours of summer daylight. In Denver (40° N) the day lasts 15 hours, and in southern Canada (50° N) there is over 16 hours of daylight – not leaving much time for stargazing.

Alaskans (60° N and beyond) have to do some of their summer sleeping absent darkness as the day lasts some 19 hours and more. And in the Arctic region – in “the land of the midnight Sun” – the Sun doesn't even set in the heart of summer. Having never been there, I can only imagine that would take some getting used to, as would the heart of winter when the Sun never rises.

All of this also applies in the Southern Hemisphere, only the dates differ – summer begins in December, fall in March, winter in June, and spring in September. Now that would really take some getting used – like, we'd have to quit dreaming of white Christmases.

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May 28, 2011
Stargazer #557

June 2011

This chart shows the night sky as appears June 1 at 11:30 p.m., June 15 at 10:30 p.m., and June 30 at 9:30 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.] / To keep your eyes adjusted to the darkness as you look a the night sky, use a red-light flashlight to view the chart. You can make your own by putting red cellophane over the light or by coloring the lens of the flashlight with a red marker pen.

• Sun
  June 1 – Sunrise: 6:24 a.m. Sunset: 8:28 p.m. / June 15 – Sunrise: 6:23 a.m. Sunset: 8:34 p.m. / June 30 – Sunrise: 6:26 a.m. Sunset: 8:37 p.m. (exact for Waco, TX)

• Moon
  June 1: New / June 8: 1st Quarter / June 15: Full / June 24: 3rd Quarter

• June Night Sky Events [Held at arm's length, the width of your fist is 10 degrees and the width of your index finger is 1 degree. The width of a full Moon is ½ degree.]
  * June 1 Wed.: The new Moon produces a partial solar eclipse but not here.
  * 8 Wed. evening: The Moon is at 1st quarter.
  * 10 Fri. evening: The Moon is one fist-width (held at arm's length) to the lower right of Saturn, and the next night is the same distance to the lower left.
  * 15 Wed.: The full Moon, called the Flower Moon, Rose Moon, Strawberry Moon, and Honey Moon, features a total lunar eclipse which won’t be seen in our part of the world.
  * 21 Mon.: The summer solstice, the longest day of the year, marks the beginning of summer in the Northern Hemisphere.
  * 23 Thu. morning: The Moon is at 3rd quarter.
  * 26 Sun. morning: The crescent Moon is to the left of Jupiter low in the east.
  * 28 Tue. morning: The crescent Moon is six moonwidths below the Pleiades star cluster with Mars further below them very low in the east just before the break of dawn.
  * 30 Thu. morning: An extremely thin crescent Moon is five moonwidths below Venus near the eastern horizon 30 minutes before sunrise.
  

• June Naked-eye Planets [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Saturn (east)
  Mornings: Venus, Mercury, Jupiter, Mars (all very low in the east at dawn)
  * Mercury is lost in glare of the the rising Sun early in the month, passes behind the Sun June 12, and then emerges low in the west after sunset late in the month.
  * Venus, still the brilliant "morning star," now rises only an hour before the Sun.
  * Mars, rising earlier each morning, is now up an hour and a half before sunrise.
  * Jupiter now rises more than two hours before the Sun and is well up in the east by dawn.
  * Saturn, in the south in the early evening, is up until the wee hours of morning.
  

• Constellation of the Month
  In the northern sky, Draco the Dragon, shaped like a backwards “S” composed of all rather faint stars, is a long constellation resembling a snake more than a dragon. Its tail starts between Polaris (North Star) and the Big Dipper’s pointer stars at the outer end of the bowl. Its body winds upward and to the right, and then back down and to the right around the Little Dipper. It then sharply winds back upward where its 4-star quadrangle-shaped head is 1½ fist-widths (held at arm's length) to the left of the bright star Vega.

• Thuban, the once and future North Star
  Polaris is the North Star of our era, but it hasn't always been, and it won't always be. Thuban, one of the faint stars of Draco, was the North Star some 5,000 years ago when Britain's Stonehenge and Egypt's pyramids were being built. Owing to precession – the Earth's gradual wobble on its axis – the point in the sky straight up from Earth's North Pole (called the North Celestial Pole) makes a big circle in the sky every 25,800 years. When there is a naked-eye star fairly near the NCP, it is regarded as the North Star of that era, yet much of the time there simply is no North Star. But what goes around, comes around: in another 20,000+ years, Thuban will again become the North Star, and then 5,000 years later, Polaris again. A challenge to see, especially under light-polluted skies, faint Thuban is located mid-way between the Little Dipper's bowl and the Big Dipper's handle. While it's not much to see, it can help us appreciate Polaris. Even though Polaris is not the brightest star in the sky as many think – it's 50th brightest – at least we have an easily visible North Star. (For all practical purposes, there currently is no South Star.)

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, June 25, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 8:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, June 11, from 8-10 p.m. See www.centexastronomy.org for more information.

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May 13, 2011
Stargazer #556

Cosmic Baseball

It's been a while since we've had a good ol' game of cosmic baseball, so let's dig out the ball, bat, and gloves and head to that sandlot in the sky. If your childhood games were like ours, bases were objects of convenience making the diamond a bit catty-whompus. Home plate might have been a bare spot in the grass, first base an abandoned ant hill, and so forth.

In cosmic baseball we also make-do with what we've got. Our diamond is formed by four stars of decreasing brightness – an informal pattern called the Diamond of Virgo on some star charts.

For home plate we use the reddish Arcturus, the brightest star in the Northern Celestial Hemisphere, Now high in the east, it's easy to find using the Big Dipper high in the north. The three stars of the dipper's handle form an arc which, continuing away from the dipper's bowl, “arc to Arcturus” three fist-widths (held at arm's length) away.

Continuing the arc another three fist-widths we come to bright bluish-white Spica which we use for 1st base. Facing south, Spica is to the lower right of Arcturus some four fist-widths above the horizon.

From there we make a left turn and go three and a half fist-widths to Denebola, our 2nd base. Denebola, to Spica's upper right, is now a little due south of straight overhead. (Don't be confused by Saturn which currently happens to be between Spica and Denebola – it's just passing through.)

Making another left turn, 3rd base is Cor Caroli three fist-widths from Denebola. Almost overhead and under the arc of the Big Dipper's handle, Cor Caroli is the faintest of the diamond stars. Finally, we make one last left turn, go two and a half fist-widths, and we've circled the bases back to home plate (Arcturus).

We now need two more positions to round out our infield. For shortstop we have not a single star but the large Coma Berenices star cluster. Situated between 2nd and 3rd bases (Denebola and Cor Caroli), it is most easily seen under dark non-urban skies. The pitcher's mound is the star about as bright as Cor Caroli located near the center of the diamond. Since it has no common name, I call it Charlie Brown.

Well, that's the infield of our cosmic baseball diamond. The outfield is composed of constellations which we'll save for another time. But for now, “Batter up!”

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April 22, 2011
Stargazer #555

May 2011

This chart shows the night sky as appears May 1 at 11:30 p.m., May 15 at 10:30 p.m., and May 31 at 9:30 p.m. from latitude 30º N. Hold the chart so the direction you are facing is at the bottom. For example, if you are facing north, turn the chart around so "Northern Horizon" is at the bottom as you hold it out in front of you. The stars on the lower part of the chart are those you will be facing in the sky. The stars at the chart's center represents the part of the sky straight overhead. [Sky chart generated using Cartes du Ciel freeware.]

• Sun: May 1 – Sunrise: 6:43 a. m. Sunset: 8:08 p. m. / May 15 – Sunrise: 6:32 a. m. Sunset: 8:18 p. m. / May 31 – Sunrise: 6:25 a. m. Sunset: 8:28 p. m. (Times exact for Waco, TX)

• Moon: May 3: New / May 10: 1st Quarter / May 17: Full / May 24: 3rd Quarter

• Night Sky Events  [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  * Early early evenings of May: The Milky Way lies flat around the horizon, making it seem to disappear.
  * May 1: May Day and Beltane, a cross-quarter day celebrating the middle of spring.
  * May 1 morning (30 minutes before sunrise): The crescent Moon, Venus, Mercury, Mars, Jupiter are all within a 10º circle very low in the east, but keep watching each morning the next couple of weeks.
  * May 6 morning: The Eta Aquarid meteor shower peaks during a very favorable waxing crescent Moon.
  * May 8 morning: Mercury is three moonwidths to lower right of Venus low in the east.
  * May 10 morning: Mercury three moonwidths to lower right of Jupiter low in the east.
  * May 11 morning: Jupiter is one moonwidth to the upper left of Venus with Mercury three moonwidths to lower left of the brilliant “morning star.”
  * May 13: Friday the 13th is an unlucky day for the superstitious; in some years this occurs two and even three times, but this year it happens but once – so is that bad luck or good luck?
  * May 13 evening: Saturn is 9º to the upper left of the bright waxing gibbous Moon.
  * May 17: The full Moon is called Milk Moon, Flower Moon, Corn Moon, and Planting Moon.
  * May 23 morning: Mars is two moonwidths above Venus with Mercury four moonwidths below low in the east.
  * May 29 morning: The crescent Moon is 5º to the upper right of Jupiter in the east.
  * May 31 morning: The crescent Moon is 6º to the left of Venus with Mercury 3º below.
  

• Naked-eye Planets   [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Saturn (southeast)
  Mornings: Venus, Mercury, Jupiter, Mars (all very low in the east at dawn)
  * Mercury spends the month low in the east at dawn and is at its best early in the month.
  * Venus, the brilliant "morning star," is edging ever nearer the rising Sun.
  * Mars is barely beginning to emerge from the rising Sun, but still a challenge to see.
  * Jupiter is beginning to emerge in the morning and is becoming prominent by month's end.
  * Saturn is in the southeast in the early evening, up all night, and sets just before dawn.
  

• Saturn    From now until the end of August Saturn will be at it best in this year's evening sky. In 2009 its rings were nearly edge-on from our view and appearing extremely thin. Last year they had opened (tilted) a bit and were more visible as seen in the Hubble Space Telescope photo (left). This year the tilt has increased somewhat as shown in the photo (right) taken March 20, 2011, by amateur astronomer Dave Eisfeldt, a member of the Central Texas Astronomical Society who lives in Waco. Note how the image taken with an inexpensive CCD camera and amateur telescope from under Central Texas skies compares respectably with the professional HST image taken from space.
• March's Big Full Moon   Many people seemed to notice that the March full Moon appeared somewhat larger and brighter than usual. Unlike the optical illusion that makes the Moon seem larger when viewed near the horizon, this appearance was no illusion. Owing to the Moon's slightly elliptical (oval-shaped) orbit, once each month it swings away from Earth (called apogee) and once nearer Earth (called perigee); there is nothing unusual about this as it occurs each month and usually goes unnoticed. This one, however, was more apparent since the full Moon happened to coincide with perigee when the Moon is 14% nearer than at apogee, so it really did look larger and brighter. This terrific image was taken March 20, 2011, by amateur astronomer Phillip Jones, a member of the Central Texas Astronomical Society who lives in Frisco, TX. (See more of his great astronomy images at www.visualuniverse.org.)
• Star Parties   The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, May 21, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 8:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is Saturday, May 14, from 8-10 p.m. See www.centexastronomy.org for more information.

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April 8, 2011
Stargazer #554

Maria Mitchell - Trail-blazer

My daughter, Karen, recently asked if I was familiar with Maria Mitchell, America's first woman astronomer. I'd heard of her, yet confessed knowing little about her – but Karen's question stirred my curiosity.

After some research, I found she was a trail-blazer, and not just in astronomy. And she seemed to be someone I wish I had known – which is not the case with all famous people I've read about. Too many, while admirable for their discoveries or other contributions, have been described as arrogant, inconsiderate, unfriendly, self-centered, or in some other manner not pleasant to be around. But not so with Maria (pronounced Ma-RYE-ah) Mitchell. She seemed pretty cool.

Born August 1, 1818, in Nantucket, Massachusetts, Maria was one of 10 children of Quaker parents, and a distant cousin to Benjamin Franklin. Owing to her forward-thinking parents, her upbringing was ahead of its time. She was taught to value education, and was instilled with the idea that men and women, being intellectual equals, should receive the same quality of education. She learned the importance of personal independence and responsibility, for women as well as for men. And although obviously bright, she modestly exclaimed, “I was born of only ordinary capacity, but of extraordinary persistency.”

Her father, an educator and later a banker, was also an amateur astronomer. With his telescope, he made observations and star measurements for the U.S. Coast Guard and taught Maria to assist him in his work. At age 12, she helped him make solar eclipse calculations, and by 14, was making navigational calculations for whaling sailors. (So much for women not being good in math!)

While still a student, she worked as a teaching assistant, and at age 17, opened her own school for a year. At 18, she became the first librarian of the Nantucket Atheneum, and continued her astronomy studies and observations.

In 1847, at the age of 29, she discovered a comet (which came to be known as “Miss Mitchell's Comet”), becoming only the second woman to do so. (The first was English astronomer Caroline Herschel, sister of William Herschel, discoverer of the planet Uranus in 1781.)

Her discovery brought her acclaim in the U.S as well as Europe, and she became the first woman elected to the American Academy of Arts and Sciences, the Association for the Advancement of Science, and the American Philosophical Society. While still a librarian, she began calculating astronomical tables for the U.S. Nautical Almanac Office and traveling to scientific meetings.

At age 38 she ended her librarian career to travel in the U.S. and Europe, first as chaperone for the daughter of a wealthy family, then on her own, and later yet with the Nathaniel Hawthorne family. In 1865 at age 47, she became professor of astronomy at the new Vassar College in Poughkeepsie, NY. As director of the college's observatory which housed a 12-inch telescope, then the third largest in the U.S., her astronomical studies focused on sunspots and surface features of Jupiter and Saturn.

She was an activist against slavery and for women’s rights. In 1873 she attended the first meeting of the Women's Congress in Seneca Falls, NY, with the likes of Susan B. Anthony, Elizabeth Cady Stanton, and other suffragists, and helped found the American Association for the Advancement of Women, serving as its president for two years.

In 1843, when still in her 20s, her questioning nature had gotten her expelled by the Quakers whereupon she began attending the Unitarian church. She saw no conflict between religion and science: “Scientific investigations, pushed on and on, will reveal new ways in which God works, and bring us deeper revelations of the wholly unknown...If (the Bible and science) seem to be (in conflict), it is because you do not understand one or the other.”

Her remarkable life ended June 28, 1889, at the age of 70. Having never married, she left no children, but was survived by a cadre of friends and admirers who, in 1902, founded the Maria Mitchell Foundation. In 1994 she was elected to the National Women's Hall of Fame.

Two other Maria Mitchell quotes offer insight into her thinking. The first: “We especially need imagination in science. It is not all mathematics, nor all logic, but it is somewhat beauty and poetry.” And the second: “We have a hunger of the mind. We ask for all of the knowledge around us and the more we get, the more we desire.” She's a kindred spirit I'd like to have known.

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March 25, 2011
Stargazer #553

April 2011

• Sun
  April 1 – Sunrise: 7:15 a.m. Sunset: 7:48 p.m. / April 15 – Sunrise: 7:00 a.m. Sunset: 7:57 p.m. / Apr. 30 – Sunrise: 6:44 a.m. Sunset: 8:08 p.m. [Times exact for Waco, TX]

• Moon
  April 3: New / April 11: 1st Quarter / April 17: Full / April 24: 3rd Quarter

• April Night Sky Events
  [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  
  * April 3: Saturn is at opposition – opposite the Sun from Earth – when it rises at sunset, is up all night, and sets at sunrise; it is also at its nearest and brightest, although at its distance of nearly a billion miles, the difference isn’t great. Also note that Saturn’s rings are more open and visible this year, especially compared to 2009 when they were nearly edge on and difficult to see.
  * April 6: Jupiter is in conjunction with (behind) the Sun, soon to become visible in the morning sky.
  * April 6 evening: The crescent Moon is 5º below the Pleiades star cluster in the west, and the next night is 7º above.
  * April 9: Mercury is at inferior conjunction between the Sun and Earth, soon to become visible in the morning sky.
  * April 16 evening: The Moon is 8º to the lower right of Saturn.
  * April 17: The full Moon is called Egg Moon, Grass Moon, and Easter Moon.
  * April 22 morning: The Lyrid meteor shower peaks but the waning gibbous Moon makes this an unfavorable year for seeing many meteors.
  * April 23 morning: Uranus is two moonwidths above brilliant Venus just before dawn, but you’ll need binoculars to see the faint Uranus.
  * April 30 morning: The crescent Moon is 6º above Venus low in the east at dawn.
  

• Naked-eye Planets
  [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  
  Evenings: Saturn (east)
  Mornings: Venus (east), Mercury (low in the east by month’s end); Saturn (west)
  
  * Mercury begins April barely visible low in the west at dusk, is soon lost in the Sun’s glare as it passes between Earth and Sun April 9, and then emerges low in the east at dawn by month’s end.
  * Venus begins April as the brilliant "morning star" in the east but by month’s end begins sliding ever nearer the rising Sun.
  * Mars is hidden in the Sun’s glare.
  * Jupiter spends the month hidden in the Sun’s glare before emerging in the morning sky in May.
  * Saturn is now up all night, rising near sunset and setting near sunrise.
  

• Constellation of the Month
  Prominent in the early evenings of April is Leo, the Lion, high in the south. With imagination one can make out a lion facing to the right. The sickle-shape represents his head; his brightest star, Regulus, is his heart; and the triangle to the left is his rump and tail. No legs are prominent as he is usually portrayed as lying down. Since the ecliptic (the path across the sky of the Sun, Moon, and planets) passes near Regulus, it is frequently visited by members of our solar system. To find Leo, face south in the early evening and look for Regulus six fist-widths (held at arm’s length) above the horizon.
  

• Astro Milestones
  
  April 25, 1990: The Hubble Space Telescope was deployed by Space Shuttle Discovery astronauts. Since its original flawed optics were corrected in 1993, it has continued to dazzle humanity with its incomparable images of the cosmos.
  
  
  April 12, 1961: Russian cosmonaut Yuri Gagarin, the first human in space, made his historic 108 minute orbital flight around Earth in the spacecraft Vostok 1. Tragically he died in a 1968 training flight preparing for another space mission.
  
  
  
  
  

• Advance Notice
  It’s only 13 years until the April 8, 2024, total eclipse of the Sun passes directly over Central Texas. This will be an event of a lifetime so make your plans early.
  
  
  

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Saturday, April 23, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 7:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX. The next monthly observatory open house is Saturday, April 9, from 7-9 p.m. See CTAS for more information.

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March 11, 2011
Stargazer #552

Getting to Know Our Solar System: Moon

Until the beginning of the Space Age in 1957, our only knowledge of the other members of our solar system came from viewing and studying objects from Earth – with naked eyes for most of human history, and then with Earth-bound telescopes for 350 years. What we learned from these observations – especially telescopic – was considerable, yet there were still great mysteries surrounding our own neighbors. Many still wondered if there might be life on Venus, or at least conditions hospitable to life. Was the Moon as dry as it appears, and was it covered with a deep layer of dust that would engulf anyone landing on its surface? And did Mars have city-linking canals or any other evidence of Martian life, living or extinct?

In this and future columns we'll look at some of what we've learned about our solar system neighbors in the last half century, and since our first Space Age explorations were of our nearest neighbor, the Moon, that's where we'll start with this column.

In January 1959, the USSR's Luna 1 became the first human-made craft to escape Earth's gravity; designed to crash-land on the Moon, it missed but became the first spacecraft to fly by the Moon and go into orbit around the Sun. Nine months later, Luna 2 did successfully crash-land on the Moon, becoming the first human-made object to come into contact with another solar system body.

The Moon is locked in synchronous rotation in its orbit around Earth so the same side always faces us, with the result that no human had ever seen the Moon's other side – until October 1959 when Luna 3 circumnavigated the Moon and gave us our first looks at the Moon's farside. As might have been expected, being more exposed to incoming meteoroids and other space debris, it was found to be far more crater-covered than the nearside.

In 1964 NASA's Ranger 7 returned the first high-resolution TV images of the Moon before its planned crash onto the Moon's surface. Then in 1966 USSR's Luna 9 soft-landed and returned the first panoramic TV images of the Moon's surface, dispelling concerns about a deeply dust-covered lunar surface. Later in 1966 NASA' Surveyor 1 also soft-landed and generated many more images of the Moon's surface as well as data about lunar soil.

Momentous history was made in July 1969 when Apollo 11 astronauts Neil Armstrong and Buzz Aldrin landed and walked on the Moon. In addition to providing truly close-up images and accounts of the Moon's surface, they returned with over 50 pounds of lunar soil and rocks for scientific study.

In 1970 USSR's Luna 17 landed the first successful robotic rover (Lunakhod 1) on the Moon which during its several months of operation returned thousands of images and more data about lunar soil. Unfortunately this important feat was overshadowed by NASA's manned Apollo missions.

After the final Apollo mission in December 1972, lunar exploration lost some of its glamour until 1994 when NASA's Clementine orbiter returned data suggesting the existence of large quantities of frozen water in the Moon's permanently shadowed polar regions. NASA's Lunar Prospector orbiter returned more data supporting the possibility of lunar water ice in 1998.

The past decade has seen several more successful lunar orbital and impactor spacecraft from a growing number of countries. While these missions continue to add to our knowledge about the Moon, including more evidence of lunar water, none has yet produced any dramatic new discoveries – but some missions are ongoing and others are in the works, so stay tuned.

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February 25, 2011
Stargazer #551

March 2011

Welcome to the “new” Stargazer featuring a bit of a change in the publication schedule and format. Rather than appearing every other week, the column will now appear twice monthly on the second and last Friday of the month. The second-Friday column will feature a narrative while the last-Friday column (like this one) will be data-driven, highlighting the events of the coming month. (This is the one you might want to clip and post on your refrigerator.) Your comments will be most welcome and helpful as we make any indicated tweaks to the new format.

• March Night Sky Events. [Held at arm's length, the width of your fist is 10º and the width of your index finger is 1º. The width of a full Moon is ½º.]
  * Mar. 1 Tue. morning: The crescent Moon is 5º to the lower left of Venus low in the southeast.
  * Mar. 4: The Moon is new.
  * Mar. 6 Sun. early evening: The crescent Moon is 6º to the right of Jupiter low in the west after sunset.
  * Mar. 12 Sat. evening: The Moon is at 1st quarter.
  * Mar. 16 Wed. early evening: Mercury is 2º to the right of much brighter Jupiter very low in the west at dusk.
  * Mar. 19 Sat.: The full Moon, called Lenten Moon, Sap Moon, Crow Moon, and Worm Moon, occurs with the Moon at perigee (nearest Earth in its elliptical orbit) thus it will appear a bit larger than usual and will produce higher-than-average tides in coastal regions.
  * Mar. 20 Sun.: Spring equinox, beginning of spring in the Northern Hemisphere when day and night are of (almost) equal length.
  * 20 Sun. all night: The bright almost-full Moon forms a right triangle with the star Spica to the left and Saturn further above after they rise around 8 p.m. in the east southeast.
  * Mar. 26 morning: The Moon is a 3rd quarter.
  * Mar. 31 Thu. morning: The crescent Moon is 5º to the upper left of Venus near the eastern horizon.
  

• March Naked-eye Planets. [The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.]
  Evenings: Jupiter (low in the west until late in month); Mercury (low in the west by mid-month); Saturn (rises in mid-evening)
  Mornings: Venus (east), Saturn (southwest)
  * Mercury begins March in the Sun but by mid-month emerges low in the west in the evening twilight and is at its best Mar. 22.
  * Venus is still the brilliant "morning star" in the eastern sky and will be until well into spring.
  * Mars is still hidden in the Sun’s glare and will be until summer.
  * Jupiter, making its last evening appearance for the year low in the west at dusk, now sets by 8:30 p.m. and before month’s end will be lost in the Sun’s glare.
  * Saturn, now up by 9 p.m., is high in the southwest by morning; by month’s end it rises at sunset and is up all night.
  

• Time Change.
  Saturday, March 12, before retiring for the night, set your clocks forward (“spring forward”) to Daylight Saving Time. Of course, we don't really save any time, and in the spring we lose an hour – so if you forget about the change, you'll be an hour late to Sunday morning activities.

• March Astro Milestones.
  * Mar. 13: The planet Uranus was discovered in 1781 by German-English astronomer William Herschel (1738-1822) from his home observatory in Bath, England.
  * Mar. 14: Birthday of Albert Einstein (1879-1955), American physicist and cosmologist who put forth his theories of relativity in 1905 and 1915.
  

• MESSENGER at Mercury.
  NASA’s MESSENGER spacecraft, launched in 2004, is due to begin orbiting the planet Mercury March 17/18. The MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) orbiter is a 1,067 pound (485 kilogram) robotic space probe designed to study the chemical composition, geology, and the magnetic field of Mercury. During three earlier flybys, as MESSENGER was being positioned for planetary orbit, it returned some tantalizing new photos and data about the planet nearest the Sun. This is only the second mission to Mercury, the first being the Mariner 10 flyby in 1975, and the first to orbit the planet.

• March Star Parties.
  The Central Texas Astronomical Society's simultaneous free monthly star parties are March 26 at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 7:30 p.m. CTAS also owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX. The next monthly observatory open house is Mar. 12 beginning at 7 p.m. See www.centexastronomy.org for more information.

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February 11, 2011
Stargazer #550

Giordano Bruno: Martyr or Fool?

The date: Feb. 17, 1600. The place: Rome, Italy. The setting: A 51-year old former cleric is securely bound to a wooden pole surrounded by dry firewood.

Within moments Giordano Bruno would become the Inquisition's next victim -- suffering a cruel and undoubtedly excruciating death for publicly espousing unapproved ideas.

In the years since his death, many have viewed Bruno as a martyr for free thought and the advancement of modern scientific ideas. Others say his martyrdom may be overrated.

That he died for freely expressing his thoughts, particularly theological, is clear: he was found guilty of holding and advocating religious ideas that the Church regarded as heretical -- namely anti-trinitarian and pantheist views and denial of supernatural tenets of Christianity, like the Virgin Birth.

Still there is room to wonder to what extent he was a martyr and to what extent a fool. Bruno was intelligent, well educated, articulate, a writer, and in his early years a man of the cloth. But he was also an enigma -- a smooth talker who could quickly ingratiate himself with the powerful and wealthy who would become his patrons, and then just as swiftly do something to infuriate and alienate them.

His self-destructive streak likely played a role in his putting himself in harm's way with the Inquisition. So, martyr or fool?

What about being a martyr for his scientific ideas? At least one charge against him had scientific overtones, namely his "claiming the existence of a plurality of worlds and their eternity."

Bruno believed in Copernicus' controversial Sun-centered theory of the cosmos, and took it a step further, stating that the cosmos, and thus the number of stars, was infinite. And if that wasn't radical enough for his day, he claimed each star was a sun like ours with planets inhabited by intelligent beings like us.

And to wave one final red flag in the face of Rome, he suggested that, in the eyes of God, all cosmic beings, including us, were of equal value.

Some science historians have pointed out that Bruno was not a scientist, that his ideas weren't original, and that he offered no new ideas, arguments or evidence. So, was he a martyr for science or just lucky to have aligned himself with some ideas, many of which would come to be widely accepted.

Whether martyr or fool, he was certainly interesting and we're still talking about him more than 400 years after his death.

• Sky Calendar.
  * Feb. 6 Sun. evening: A crescent Moon is to the right of Jupiter in the west.
  * Feb. 11 Fri.: The Moon is at 1st quarter.
  * Feb. 18 Fri.: The full Moon is called Wolf Moon, Snow Moon, and Hunger Moon.
  * Feb. 24 Thu.: The Moon is at 3rd quarter.
  

• Naked-eye Planets. (The Sun, Moon, and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.) Evening: Bright Jupiter in the southwest sets before 10 p.m. Morning: Brilliant Venus dominates the southeast with Saturn in the southwest.

• Astronomy Weekend. It's not too late to register for my family-oriented astronomy weekend Feb. 25-27 at U-Bar-U Retreat Center near Kerrville, TX. For details see Astronomy Weekend elsewhere in this Web site.

• Astro Milestones. Feb. 4 is the birthday of American astronomer Clyde Tombaugh (1906-1997) who on Feb. 18, 1930, discovered Pluto on photographs he had taken from Lowell Observatory near Flagstaff, Arizona. Feb. 15 is the birthday of Italian mathematician and astronomer Galileo Galilei (1564-1642).

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January 22, 2011
Stargazer #549

Angular Distances

Beginning stargazers are often frustrated when trying to tell a friend how far a night sky object appears to be from another. Just how far apart do Polaris and the Big Dipper seem to be? Inches? Feet? Miles? Without a common frame of reference such measures are meaningless. Nor is it helpful to know actual distances, like an object is 20 light years from another.

Fortunately an easy-to-use method employing degrees to measure angular distances is helpful, not only in expressing distances between objects, but also in indicating sizes (like a constellation) and an object's distance above the horizon.

From our perspective, the night sky appears as a half sphere, like a giant overhead bowl on which the sky objects are painted. A sphere being 360 degrees around, a half sphere is 180 degrees, thus the angular distance (the distance measured in degrees) across the sky from any point on the horizon to the corresponding opposite point is 180 degrees, and straight overhead (called the zenith) is 90 degrees from the horizon.

This approach gives us a common frame of reference, but maybe you're thinking: "OK, but how can I measure degrees without special equipment?" Well, you're in luck as there's handy (pun intended) method for approximating degrees using your hand held at arm's length. While it doesn't give precise values, it works great for casual stargazing.

Holding your hand at arm's length and closing one eye, the outer joint of your index finger is about 1 degree across. The width of your fist is about 10 degrees across, and a wide open hand span is about 20 degrees.

We can immediately see that Polaris is some 30 degrees (three fists) from the nearest Big Dipper star, that Orion's three belt stars span about 3 degrees (three fingers), the Big Dipper is near 25 degrees long, and the full Moon is about 1/2 degree in diameter. And you can tell your friend that interesting object you're tying to point out to her is about 40 degrees above the horizon. So you do indeed have a most handy measuring device always at your disposal.

• Next Two Weeks. Avg. sunrise: 7:23 a.m.; avg. sunset: 6:01 p.m. (exact for Waco, TX)
  * Tue. morning the Moon, Saturn, and Spica form a triangle in the south with Spica nearest the Moon.
  * The Moon is at 3rd quarter Wed.
  * The mornings of Jan. 29 & 30 a crescent Moon is to the right, then below, Venus in the southeast.
  * Feb. 2 is Candlemas, a cross-quarter day celebrating the middle of winter; it's also Groundhog Day and whether or not he sees his shadow, there will be 46 more days of winter.
  * The Moon is new Feb. 2.
  

• Naked-eye Planets. Evening: Bright Jupiter in the southwest sets at 10 p.m. Morning: Brilliant Venus dominates the southeast with Mercury near the southeastern horizon as dawn breaks; Saturn is high in the south.
  

• Star Parties. The Central Texas Astronomical Society's simultaneous free monthly star parties are tonight at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at 6 p.m. (weather permitting). For more information see www.centexastronomy.org. For directions to the Wetlands, see Maps & Directions elsewhere in this Web site.
  

• Astronomy Weekend. I will be conducting a family-oriented astronomy weekend Feb. 25-27 at U-Bar-U Retreat Center near Kerrville, TX. For details see Astronomy Weekend elsewhere in this Web site.

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January 8, 2011
Stargazer #548

The Great Winter Arc

It's the time of year when the Great Winter Arc region is prominent in the evening sky. One of my favorite regions, it is especially dazzling because it contains the greatest concentration of bright stars found anywhere in the night sky.

Of the 21 brightest stars in all the night sky, called 1st magnitude stars, seven are in the Great Winter Arc region.

The region contains six constellations -- Orion, Taurus, Canis Major, Canis Minor, Gemini, and Auriga -- and is home to the night sky's brightest star and most famous star cluster.

Other than the Big Dipper, Orion the Hunter is probably the most recognizable constellation thanks in part to its three equally-bright and equally-spaced belt stars which are hard to miss.

Sitting in the middle of the Great Winter Arc region, it contains reddish Betelgeuse and white Rigel, two of the seven 1st magnitude stars. Three hours after sunset, look for Orion well up in the southeast.

While Orion is within the arc, it is not part of it. The arc starts with the night sky's brightest star, Sirius, in Canis Major the Big Dog. Look for Sirius blazing below Orion.

The next star in the arc is Procyon two and a half fist-widths (held at arm's length) to Sirius' left. It is the only bright star in Canis Minor the Small Dog.

Two fist-widths to Procyon's upper left are reddish Pollux and white Castor, the heads of the Gemini twins with the rest of the constellation to the right toward Orion. (Castor barely misses being 1st magnitude.)

The arc ends at creamy-colored Capella, the brightest star in Auriga the Charioteer, the rest of which stretches downward toward Orion. Capella is three fist-widths above Castor.

The region's final constellation is Taurus the Bull with the red star Aldebaran, the angry bull's fiery eye. Aldebaran is two fist-widths above Betelgeuse.

And the Great Winter Arc region's final treat is the lovely and famous Pleiades star cluster (also called the Seven Sisters) located just over a fist-width above Aldebaran.

• Next Two Weeks. Avg. sunrise: 7:28 a.m.; avg. sunset: 5:48 p.m. (exact for Waco, TX)
  * Sun. and Mon. evenings the Moon is within a fist-width of Jupiter.
  * Each morning for the next two weeks Venus is within a fist-width to the left of Scorpius' brightest reddish star Antares.
  * The Moon is at 1st quarter Wed.
  * The Jan. 19 full Moon is called Old Moon and Moon After Yule.
  

• Naked-eye Planets. (The Sun, Moon, and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis.) Evening: Brilliant Jupiter is low in the west and down by 11 p.m. Morning: "Morning star" Venus dominates the southeast with Saturn higher above. Mercury is visible as dawn breaks near the southeastern horizon much of the month.

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