Stargazer Columns 2012

NOTE: With the Aug. 24, 2012, column, my Stargazer column is being retired. Having just turned 72 years of age, and after 22 1/2 years of writing 587 columns, I've enjoyed about all I have the energy to handle. I truly hope you've enjoyed Stargazer and will continue to visit this website for its other features. And note, with the exception of 1993-1997, previous Stargazer columns can be seen in the archives.
Regards, Paul

Aug. 24, 2012: September 2012
Aug. 10, 2012: Perseid Meteor Shower
July 27, 2012: August 2012
July 13, 2012: Star or Planet -- How Can You Tell?
June 22, 2012: July 2012
June 08, 2012: Stargazing in the Summer
May 25, 2012: June 2012
May 11, 2012: Transit of Venus
Apr. 27, 2012: May 2012
Apr. 13, 2012: Solar Eclipse Coming Our Way
Mar. 23, 2012: April 2012
Mar. 09, 2012: More Stargazing Below the Equator
Feb. 24, 2012: March 2012
Feb. 10, 2012: Stargazing Below the Equator
Jan. 27, 2012: February 2012
Jan. 13, 2012: 2012 Night Sky Highlights

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August 24, 2012
Stargazer #587

September 2012

Your guide to the stars: You can use the chart as a guide when looking at the night sky. The chart shows the sky as it will be at 10:30 p.m. early in the month, 9:30 p.m. at mid-month, and 8:30 p.m. late in the month.

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 the "N" representing north is at the bottom as you hold it out in front of you. The center of the chart represents the portion of the sky you see if you look straight up.

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
  September 1 - Sunrise: 7:04 a.m.; Sunset: 7:52 p.m. / September 15 - Sunrise: 7:13 a.m.; Sunset: 7:34 p.m. / September 30 - Sunrise: 7:22 a.m.; Sunset: 7:15 p.m. [Times exact for Waco, TX]

• Moon
  September 8: 3rd Quarter / September 15: New / September 22: 1st Quarter / September 29: Full

• Night Sky Events Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ. ** = don't miss events.
  ** 8 Sat. morning: The 3rd quarter Moon passes within 1° (two moonwidths) to the right of Jupiter high in the east.
  ** 9 Sun. early morning: The Moon occults Ceres - see below.
  10 Mon.: Mercury is at superior conjunction with (behind) the Sun and passing into the evening sky.
  12 Wed. morning: "Morning star" Venus is flanked by a crescent Moon 4° to the right and the subtle Beehive star cluster 3° to the left, all low in the east 2 hours before sunrise; all three will barely fit within the same field of view of most binoculars.
  13 Thu. morning: Venus passes 2½° (five moonwidths) to the right of the Beehive.
  14 Fri. morning: A thin crescent Moon is 6° to the right of Leo's alpha star Regulus just above the eastern horizon as dawn is breaking.
  15 Sat.: The Moon is new as it passes between the Earth and Sun.
  15 Sat. early evening: Mars passes 1° to the lower left of Libra's alpha star Zubenelgenubi (an easy binocular double) low in west at dusk.
  18 Tue. early evening: A thin crescent Moon is 9° to the left of Saturn near the western horizon at dusk.
  19 Wed. evening: The crescent Moon is 2° to the left of Mars low in the southwest soon after dark.
  20 Thu. evening: The waxing crescent Moon is 7° to the right of Scorpius' alpha star Antares in the southwest; Mars, looking like Antares, is 16° to the Moon's lower right.
  22 Sat.: Autumn equinox - the beginning of fall in the Northern Hemisphere when night and day are of approximately equal length.
  22 Sat. evening: The Moon is at 1st quarter.
  29 Sat.: The full Moon is called the Fruit Moon and Corn Moon, and being the full Moon nearest the fall equinox it is also this year's Harvest Moon.
  Note: September is a good month to see the zodiacal light in the morning an hour before dawn begins to break; under very dark skies, look for a triangular-shaped cosmic cloudiness rising 30° or more from the eastern horizon.
  

• 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: Mars, Saturn
  Morning: Venus, Jupiter
  * Mercury spends the month hidden in the Sun's glare, passing behind the Sun Sep. 10.
  * Venus is still the brilliant "morning star" dominating the eastern sky.
  * Mars, low in the west southwest at dark, now sets well before midnight.
  * Jupiter, rising around midnight, is high in the south by morning.
  * Saturn, low in the west southwest at dark, sets by 10 p.m. early in the month; by month's end it sets soon after sunset essentially ending its 2012 evening appearance.
  

• Moon Occults Ceres
  [For telescopes] Early Sunday morning, Sept. 9 (think late Saturday night), the Moon occults (passes in front of and temporarily hides) Ceres, the largest member of the asteroid belt. According to Starry Night Pro 6, for Waco, the occultation begins ~2:20 a.m. (CDT) when the asteroid disappears behind the lower right illuminated part of the Moon near the terminator, and reappears at ~2:41 a.m. from the right un-illuminated side.
  Being only 600 miles in diameter, the tiny the ~8th magnitude Ceres will appear as a faint star-like point of light with no discernible shape. They will be low in the ENE at an altitude of ~15-20° so observe from a location with a clear, low view. (Trees and the building might be a problem for viewing from the TRS observing field, but the Meyer telescope should be high enough above the trees to see it.)
  FYI, another computer sky-simulation program I frequently use (an older version of TheSky) gives somewhat different (later) times for this occurrence, but being an older program, it doesn't allow for updating with the latest data, so I have more confidence in Starry Night. Curiously, I've found little on the Internet, including no mention by Sky & Telescope's or Astronomy's websites.

• Milky Way Triangle Region
  High overhead in the early evening are three bright stars - Vega, Deneb, and Altair - forming the Milky Way Triangle. Viewed from dark skies away from urban light pollution, the bright plane of our Milky Way galaxy is seen running through the triangle, hence its name (although it is also called the Summer Triangle.) The Milky Way Triangle is not an official constellation but rather an asterism, an informal but easily-recognizable pattern of stars.
  In early September, an hour and a half after sunset, Vega, the brightest of the three triangle stars, is near the sky's straight-up point, called the zenith. Altair, second brightest of the trio, is three fist-widths (held at arm's length) to the south southeast of Vega with Deneb two fist-widths the northeast of Vega (and four fist-widths from Altair). Deneb is situated within the Milky Way with Vega is to the west and Altair to the east of the galactic plane.
  Vega, the fifth brightest star in the entire night sky, is relatively nearby at a distance of 25 light years. It gained fictional fame when, in Carl Sagan's 1985 novel (and movie) Contact, it was the star system from which radio messages were received from other intelligent beings. It is the alpha star of the small constellation Lyra the Musical Lyre which features a small parallelogram of four stars that appears to be hanging from Vega. Your fist, held at arm's length, can completely cover Lyra's major stars.
  Altair, the night sky's 13th brightest star, is the alpha star of the constellation Aquila the Eagle and is 17 light years distant. With Altair as its head, the eagle is flying in a north northeasterly direction along the eastern edge of the Milky Way.
  Deneb, the 20th brightest star, is the alpha star of the constellation Cygnus the Swan. Deneb represents the swan's tail as the big bird flies south southwest along the Milky Way; the fainter star Albireo represents the swan's head two fist-widths from Deneb.
  As with many things in nature, appearances can be deceiving. While our Sun is blindingly bright to us, it is fainter than any of the triangle stars, and only appears brighter because it is so much closer. And while Deneb appears to be the faintest of the triangle stars, in reality it is brighter than Vega, Altair, and our Sun combined. A white supergiant star, Deneb is a whopping 3,262 light years distant, making it one of the most distant stars we can see with our naked eyes.
  The Milky Way Triangle, which became visible low in the east in the early summer, will be in our evening sky until early winter when it sets in the west soon after dark.

• Astro Milestones
  German astronomer Johann Galle and his student assistant Heimrich d'Arrest discovered the planet Neptune September 23, 1846, from Germany's Berlin Observatory. Their discovery was made based on the predictions and position-calculations data sent them by Urbain Jean Joseph Leverrier of France.

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

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August 10, 2012
Stargazer #586

Perseid Meteor Shower

It's time once again for the popular Perseid meteor shower, and this year we might get two nights of increased meteor activity. The shower is predicted to peak the morning of Aug. 12, thus there could be good meteor viewing the nights of Aug. 11/12 and 12/13.

The best viewing will likely be from dark until moonrise rise, and even after the Moon rises - around 2 a.m. on Aug. 12 and 3 a.m. on Aug. 13 - it will be in a waning crescent phase low in the east, and shouldn't create major interference.

Meteors are best seen with naked eyes from dark skies away from light-polluted cities, but brighter meteors can be seen even from within urban areas. While in a reclined position - and reclining lawn chairs work great - slowly pan the entire sky, focusing most of your attention on the darkest part which is usually overhead.

Meteors are tiny pieces of space debris entering our atmosphere at such high speeds - many thousands of miles per hour - that friction with air molecules causes them to burn up, creating those beautiful momentary streaks across our sky. They resemble "falling stars" and "shooting stars" - hence their nicknames - although they have no connection with the stars we see in the night sky. Most meteors are small pieces of debris no larger than a pebble, and many as tiny as a grain of sand.

Meteors are commonly seen virtually every night, especially under dark, moonless skies, but several times each year we have meteor showers during which an above-average number of meteors are seen - like the Perseid meteor shower which occurs each year around Aug. 12.

Many wonder why meteor showers occur the same time each year, and so did astronomers until about 150 years ago. Soon after the discovery of Comet Swift-Tuttle in 1862, astronomers could finally answer the question. They noticed an association between this comet and the annual Perseid meteors, and thus were able to establish that meteor showers are linked to comets.

Dubbed "dirty snowballs" by astronomer Fred Whipple, comets are chunks of frozen rock and ice, most no more than several miles in diameter, left over from the formation of our solar system five billion years ago. Countless millions, of even billions, of comets swarm around the Sun far beyond the orbit of Pluto in what is called the Oort Cloud, and most will remain out there throughout the life of our solar system. Some, however, have their orbits perturbed in such a way that they swing down into the inner solar system where heat from the Sun melts off part of their outer layer, freeing and distributing bits of rocky debris along their path.

By coincidence, the orbital paths of some comets intersect the orbital path of Earth as it makes its annual trip around the Sun. When this happens, Earth passes through the stream of debris left in the comet's path, resulting in an above-average number of meteors, and thus a meteor shower.

Image: Meteor showers result when Earth passes through comet debris

Meteor shower names derive from the constellation from which the meteors seem to radiate - the Perseids from Perseus, the Leonids from Leo, and so forth. The key word here is "seem" as the meteors don't actually originate from within their named constellation - they only appear to. While the stars forming constellation patterns are many light years away, the pieces of debris blazing across our sky are a mere 50-70 miles up in our atmosphere.

And the name doesn't mean that meteors will only be seen in or near the constellation from which they radiate. As with all meteor showers, Perseids are likely to be seen in any part of the sky, not just in the direction of Perseus. So why are they called Perseids? If you trace their paths back far enough, the paths converge at their radiant point within the constellation for which they are named. The radiant point for the Perseids is just inside Perseus, near the Perseus-Cassiopeia border.

As you watch a Perseid meteor burn up in our atmosphere, think about the fact that you're witnessing the demise of an ancient piece of debris that was once part of Comet Swift-Tuttle, and which had been around since the birth of our solar system.

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July 27, 2012
Stargazer #585

August 2012

Your guide to the stars: You can use the chart as a guide when looking at the night sky. The chart shows the sky as it will be at 11 p.m. early in the month, 10 p.m. at mid-month, and 9 p.m. late in the month.

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 the "N" representing north is at the bottom as you hold it out in front of you. The center of the chart represents the portion of the sky you see if you look straight up.

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
  August 1 - Sunrise: 6:45 a.m.; Sunset: 8:25 p.m. / August 15 - Sunrise: 6:54 a.m.; Sunset: 8:12 p.m. / August 31 - Sunrise: 6:04 a.m.; Sunset: 7:54 p.m. [Times exact for Waco, TX]

• Moon
  August 1: Full / August 9: 3rd Quarter / August 17: New / August 24: 1st Quarter / August 31: Full

• Night Sky Events Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ. ** = don't miss events.
  1 Wed.: Lammas, a cross-quarter day celebrating the middle of summer.
  1 Wed.: The full Moon is called the Grain Moon and Green Corn Moon.
  7 Tue. evening: Slow-moving Saturn, spending the entire month less than 5° above Virgo's alpha star Spica, passes closest tonight.
  9 Thu. morning: The Moon is at 3rd quarter.
  10 Fri. morning: The waning gibbous Moon passes within 4° to the upper right of the Pleiades star cluster although its glare will rather overpower the lovely cluster.
  11 Sat. morning: The Moon has now moved just above Jupiter, Aldebaran and the Hyades star cluster.
  ** 11 Sat. all night: The Perseid meteor shower peaks with no Moon interference until after midnight.
  13 Mon. morning: The waning crescent Moon is 4° above Venus low in the east before dawn - and is 8° below the "morning star" the next morning.
  ** 13 Mon. evening: Spica (bottom), Mars (middle), and Saturn align low in the west southwest; they are nearly equal in brightness and will fit within the same field of view of most binoculars.
  14 Tue. evening: Reddish Mars passes within 3° of creamy Saturn.
  15 Wed. morning: Venus is at greatest elongation 46° west of the rising Sun.
  15 Wed. morning: The thin waning crescent Moon is 8° to the upper right of Mercury low in the east as dawn begins to break.
  16 Thu. morning: Mercury is at greatest elongation 19° from the rising Sun with an ever-thin crescent Moon to its lower right.
  17 Fri.: The Moon is new.
  18 Sat. morning: Mercury passes 2° to the right of the Beehive star cluster near the east northeastern horizon about an hour before sunrise; binoculars will help with the lovely but faint star cluster.
  ** 21 Tue. early evening: The waxing crescent Moon, the star Spica (lower right), Saturn (upper right), and Mars (upper left) form a tight lumpy-jawed square very low in the west southwest at dusk; all four will be seen within the same field of view of most binoculars and should be pretty awesome.
  24 Fri.: Neptune is at opposition - on the opposite side of Earth from the Sun.
  24 Fri. evening: The Moon is at 1st quarter.
  31 Fri.: The full Moon, being the second for the month, is called a Blue Moon although the name has nothing to do with its color.
  Note: August and September are the best months to see the zodiacal light in the morning an hour before dawn begins to break; under very dark skies, look for a triangular-shaped cosmic cloudiness rising 30° or more from the eastern horizon.
  

• 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: Mars, Saturn
  Morning: Mercury, Venus, Jupiter
  * Mercury starts the month in the glare of the rising Sun, quickly emerges low in the east, reaches it best by mid-month, and begins dipping back into the Sun's glare by month's end.
  * Venus, the brilliant "morning star," is at its highest above the rising Sun in latter August.
  * Mars, low in the west southwest in the early evening, now sets before midnight.
  * Jupiter, rising in the wee hours, is well up in the east by morning, and further above the much brighter Venus.
  * Saturn, in the west southwest in the evening, sets before midnight early in the month and soon after sunset by month's end; it is nearing the end of its 2012 evening appearance.
  

• Perseid Meteor Shower
  The Perseid meteor shower is predicted to peak in the early morning of Aug. 12, thus there might be increased meteor activity either or both of two nights - Aug. 11/12 and 12/13. The best viewing will likely be from dark until the Moon rises an hour or two after midnight. Meteors are best seen with naked eyes from less light-polluted rural areas. In a reclined position, slowly pan the entire sky while focusing attention on the darkest part which is usually overhead.

• Total Solar Eclipse Early Notice
  It is now only 5 years until Aug. 21, 2017, when a 70-mile wide shadow of a total solar eclipse passes across the middle of the U.S. from Oregon to South Carolina. Start making your travel plans.

• Sagittarius' Tea Party Region
  This night sky region has nothing to do with current "tea party" politics, but it does involve shameless deceit involving the two signature constellations of summer - Sagittarius and Scorpius.
  You're probably familiar with the story of the Trojan Horse in which the Greeks used a gift horse to entice the city of Troy to lower its defenses, making it vulnerable to a sneak attack.
  Image: Trojan Horse from Greek mythology (19th century painting)
  Here the trickster is Sagittarius the Centaur-archer who disguises himself as a cosmic teapot in to entice his neighbors, Scorpius the Scorpion and Lupus the Wolf, into a deadly trap. Inviting them over for a neighborly cup of tea, he intends to shoot them with his bow and arrow when they get within range. Not only does he dislike having these guys for neighbors, the nearby Corona Australis the Southern Crown suggests this is also a territorial fracas to determine who rules this area of the sky.
  The drama occurs far to the south with its players visible in the early evenings of summer. The story ends like another classic - the one about the lady or the tiger. We are left to wonder if the scorpion and wolf will be deceived by Sagittarius' disguise, or perhaps they've also heard the Trojan Horse story.
  Sagittarius looks more like a teapot than an archer, and Scorpius, with some imagination, does resemble a scorpion with his hooked tail to the lower left, pincers to the upper right, and the bright reddish star Antares as his head. Lupus, partly below the horizon, doesn't look like much of anything, and Corona Australis is so faint and near the horizon as to be nearly unnoticeable.
  The heart of the Milky Way galaxy runs through Scorpius and Sagittarius, making it one of the richest areas of the night sky, full of star clusters and nebulae. When viewed from beyond city lights, the brightest part of the Milky Way looks like steam arising from the spout of the Sagittarius' teapot.
  Image: Facing south, Sagittarius' Tea Party Region is prominent in the evenings of late summer

• Astro Milestones
  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 Sat., Aug. 11, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at dark. CTAS owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is also Sat., Aug. 11, 8-10 p.m. See www.centexastronomy.org for more information.

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July 13, 2012
Stargazer #584

Star or Planet -- How Can You Tell?

Have you ever seen a bright star and wondered if that "star" might be a planet? Planets and stars are different types of objects, yet they look alike to the naked eye. Indeed, the word planet derives from the Greek word "planetes" which means wanderer, thus planets were considered wandering stars by our ancestors.

So, without using a telescope, how can one tell which is which? One way, of course, it to watch any suspicious object night after night to see if it moves, or wanders, relative to the surrounding stars. But that can take many nights as planets move slowly, and the more distant ones have to be watched for weeks, especially when there are no nearby stars.

For casual observers, there's no foolproof way to pick out the planets from the myriad of stars, but some pointers can help. First, there are only five naked-eye planets - Mercury, Venus, Mars, Jupiter, and Saturn - and they are usually brighter than the vast majority of naked-eye stars. (Technically, Uranus can be seen naked-eye, but it's at the limit of visibility, and seeing it requires good eyes and very dark skies.)

Start by noticing the brightness of the object in question. Venus and Jupiter always outshine all the stars, and the other three are usually brighter than all but the brightest stars. So brightness is the first clue.

Second, perhaps you've heard that "stars twinkle and planets don't" - and this tends to be true, although the difference can be subtle and varying. Twinkling (called scintillation) is caused by turbulence in Earth's atmosphere, so that greater air instability produces more twinkling while steadier air makes for less. So, when the stars are twinkling noticeably, look for any brighter objects that aren't.

Third - and this is quite helpful - look in the right part of the sky. Planets orbit the Sun on nearly the same plane, so they all closely follow the ecliptic - the Sun's path across our sky. And since the Moon orbits the Earth on nearly this same plane, it too travels close to the ecliptic.

Like the Sun and Moon, the planets rise in the east and set in the west, owing to the Earth's west-to-east rotation on its axis. Facing south with your arms outstretched slightly more than 180 degrees, any visible planets will be in front of your arms - never behind you or even straight overhead. All that are above the horizon will be somewhere along the great ecliptic arc beginning in the east (your left), rising and tilting somewhat to the south, and ending in the west (your right).

There are two additional things to know about the ecliptic. The season and time of night affect the ecliptic's exact rising and setting points, making them sometimes a little left or right of due east and west. And, the amount of southerly tilt varies so that sometimes the ecliptic is tilted more than half way down toward the southern horizon while at other times it reaches nearly straight up. Still, knowing the approximate path is useful in identifying planets.

The inner planets, Venus and Mercury, orbit nearer the Sun inside Earth's orbit. Thus, when they are not hidden in the Sun's glare, they are seen only in the evening soon after sunset low in the west or in the morning soon before sunrise low in the east - never real high in the sky and never deep into the night. When visible, Mercury, being so near the Sun, is rarely seen after twilight.

The outer planets, Mars, Jupiter and Saturn, when not passing behind the Sun, might rise or set - and thus may be seen - any time of the night. When they are on the opposite side of Earth from the Sun - a position called opposition - we are at our nearest to them, making them appear at their brightest and largest.

Currently there are great opportunities for identifying four planets among the stars as Saturn and Mars are visible in the evening while Venus and Jupiter are up in the morning.

Soon after dark Saturn and Mars are less than half way up in the southwest. Saturn is currently less than 5 degrees (one-half fist-width held at arm's length) to the upper right of the star Spica. Almost equally bright, Spica is twinkly white while Saturn shows a steady creamy tint. About 20 degrees (two fist-widths) to their lower right, Mars has a reddish tint with no notably bright stars nearby. Mars is gradually approaching Saturn and Spica, and will pass between them in mid-August.

In the morning before dawn, Venus and Jupiter are very low, rising in the east. "Morning star" Venus vastly outshines all the real stars as does Jupiter, although the king of the planets can't hold a candle to his queen. Venus is near the reddish star Aldebaran, passing within two moonwidths July 8-10, but 1st-magnitude Aldebaran, 14th brightest of all the stars, pales in comparison to Venus. Jupiter, 5 degrees above, is nearly half way between Venus and the lovely Pleiades star cluster. Venus and Jupiter are drifting further apart each morning.

Here's hoping these pointers help you learn to pick out our brighter solar system neighbors from among the seemingly countless background stars.

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June 22, 2012
Stargazer #583

July 2012

Your guide to the stars: You can use the chart as a guide when looking at the night sky. The chart shows the sky as it will be at 11:30 p.m. early in the month, 10:30 p.m. at mid-month, and 9:30 p.m. late in the month.

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 the "N" representing north is at the bottom as you hold it out in front of you. The center of the chart represents the portion of the sky you see if you look straight up.

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. [Times exact for Waco, TX]

• Moon
  July 3: Full / July 10: 3rd Quarter / July 18: New / July 26: 1st Quarter

• Night Sky Events Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ. ** = don't miss events.
  July 1 Sun. morning: Venus is 5 degrees below Jupiter low in the east just before dawn.
  2 Mon. early evening: The Beehive star cluster is 2 degrees to the upper right of Mercury low in the west at dusk; binoculars will help seeing the faint moon-sized cluster.
  3 Tue.: The full Moon is called the Hay Moon and Thunder Moon.
  ** 9 Mon. morning: This morning offers a dramatic gathering as Venus, passing within the V of the Hyades star cluster, is less than two moon-widths to the upper left of the reddish star Aldebaran with Jupiter 5 degrees above them and the Pleiades star cluster another 8 degrees up - all low in the east just before dawn; all are naked-eye objects, but binoculars will enhance the view.
  10 Tue. morning: The Moon is at 3rd quarter Moon, and "morning star" Venus is at its brightest at magnitude -4.5.
  ** 14 Sat. morning: The waning crescent Moon is 4 degrees to the lower right of the Pleiades star cluster with bright Jupiter, brilliant Venus, and the star Aldebaran below them low in the east.
  ** 15 Sun. morning: This morning the crescent Moon is between the two planets.
  19 Thu.: The Moon is new, passing between the Earth and Sun.
  ** 24 Tue. early evening: The waxing crescent Moon is 6 degrees to the lower left of Mars with the Saturn and the star Spica further to the upper left, all low in the west.
  ** 25 Wed. early evening: By tonight the Moon is 6 degrees to the left of Spica with Saturn 9 degrees to the upper right and Mars well to their lower right.
  26 Thu. evening: The Moon is at 1st quarter.
  30 Mon. morning: Jupiter passes within 5 degrees to the upper left of the star Aldebaran with Venus well to their lower left low in the east.
  Note: The early evenings of latter July find the center of our Milky Way galaxy some 30 degrees (three fist-widths held at arm's length) above the southern horizon, as high as it ever gets in our sky.
  

• 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 (early in the month), Mars, Saturn
  Morning: Venus, Jupiter
  * Mercury starts the month low in the west at dusk and begins sinking into the setting Sun by mid-month.
  * Venus, becoming the dominant "morning star" low in the east, is keeping company with Jupiter.
  * Mars, in the west southwest in the early evening, sets around midnight.
  * Jupiter, well up in the east in the morning, is above the even brighter Venus; the king and queen of the planets are slowly separating each morning.
  * Saturn, in the southwest in the evening, sets well after midnight.
  

• Midyear Milestones
  The midpoint of the year 2012 occurs July 2 at 1 a.m. local daylight time. / 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 is about 3% greater than when nearest the Sun at perihelion in early January. (This variation has little effect on Earth's atmospheric temperature, and has nothing to do with Earth's seasons.)

• Macho Quadrangle Region
  As a kid in the early 1950s I loved watching Houston's Friday Night Wrestling on TV - until I discovered it was faked. Since that betrayal, I've never watched wrestling since, but that youthful experience gave me the inspiration for an area of the night sky I have named the Macho Quadrangle. Prominent in the early evening from June through September, this region has all the ingredients for a really hokey TV wrestling match.
  Four 1st magnitude stars - Arcturus, Vega, Altair, and Antares - represent the four corner posts of the ring. Entering from the northwest, between Vega and Arcturus, is the well-known defending champion Hercules the Strong Man. He's large, but having no really prominent stars, he's not real bright. We know he's the champ because beside him is his crown, Corona Borealis the Northern Crown, and his personal trainer, Bootes the Herdsman.
  Hercules' opponent is the lesser-known Ophiuchus the Serpent Bearer, not quite as large but slightly brighter. As the challenger he employs some dramatics intended to intimidate the champion - he has entered the ring from the southeast corner, between Antares and Altair, holding Serpens the Serpent in hands.
  If you have ever watched wrestling - and you don't have to confess if you have - you know the announcers always state combatants' weights, so we have Libra the Scales just outside the ropes between Arcturus and Antares. (Have you ever wondered why they don't also announce things like IQs or cholesterol levels?)
  The winner of championship matches gets to wear a championship belt, the huge buckle of which looks more like a belly-protecting shield, and just outside the ring between Antares and Altair is Scutum the Shield waiting to be presented to the winner of the cosmic clash in the Macho Quadrangle.
  Image: Facing south, the Macho Quadrangle Region is prominent in the early evenings from June through September

• Friday the 13th
  July 13 is this year's third Friday the 13th, the other two having come in January and April. Considered an unlucky day by the superstitious who must also believe that "the third time is charm," will the two superstitions combine to make this an especially unlucky day, or will they cancel each other out making it an ordinary day? Thank goodness I don't have to figure that one out since I'm not superstitious.

• Astro Milestones
  July 20, 1969, U.S. astronauts Neil Armstrong and Buzz Aldrin became the first humans to land and walk on the moon.

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Sat., July 14, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at dark. CTAS owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is also Sat., July 14, 8-10 p.m. See www.centexastronomy.org for more information.

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June 8, 2012
Stargazer #582

Stargazing in the Summer

Like many avocations, stargazing can be a year-round activity as any clear night offers interesting things to see. Regardless of the season, there will always be stars and constellations, and often the Moon and one or more planets.

Yet the seasons do affect stargazing, and notably summer verses winter. A most obvious difference relates to the objects available for viewing since the winter and summer night skies feature different constellation shows.

But first, let's consider some other seasonal differences.. Being a cold weather wimp, I confess to preferring summer stargazing. No matter how lovely the winter might be, I can't enjoy viewing it if I'm shivering and my feet and hands are aching cold - so I much prefer warmer weather.

There are, however, some disadvantages to summer stargazing, like summer's later sunsets and earlier sunrises which make for shorter nights. While winter nights offer upwards of 14 hours of darkness (at our latitudes), summer nights can be as short as 10 hours. And there's the inconvenience of darkness coming so late in the summer. With daylight saving time, summer star parties can't get going good before 10 p.m., and that's kind of late for kids and old codgers like me.

And then there are the critters - especially mosquitoes which seem more active in the summer. You'll want to have bug spray available, but be careful how you use it at star parties. Never apply spray around telescopes or binoculars as the chemicals can damage the optics.

Snakes and other animals are more active in the summer, so if you're stargazing in a grassy area, be aware. I've never encountered a snake while observing, and hope I never do, but one of my stargazing buddies, Willie Strickland, had a startling encounter at our astronomy club's observatory.

As he was about to unlock the observatory door in the dark, he dimly saw something that made him step back. With his flashlight, he saw a long snake climbing up the door casing on its way to devouring some bird eggs. In our desire to live compatibly with nature, we had left undisturbed a bird nest in the entrance way, not being aware of its attractiveness to chicken and rat snakes. Fortunately, Willie wasn't bitten, but he was certainly rattled by the experience.

Another time we saw a tarantula spider ambling across the viewing field, but he was just as anxious to get away from us as we were to have him leave. We've also encountered skunks and other critters, but they didn't seem concerned about us since we didn't make threatening gestures toward them.

In far west Texas, the Davis Mountains and Big Bend National Park are famous for dark skies, making them popular destinations for stargazers, but there are certainly potentially hazardous inhabitants out there. Black bears and mountain lions come to mind immediately, but fortunately they are generally people-shy and rarely seen. Since my first trip to the area in 1970, I've been back 30 or more times, and I've never seen a bear or mountain lion.

But I've seen many peccaries, also known as javelinas. (Peccaries are often erroneously called javelina hogs, and while they bear some resemblance to hogs, they are not in the pig family.) Although not particularly aggressive, they have sharp teeth and can be dangerous if one gets between them and food. They wander around in small bands, especially at night, and often come right through campsites searching for food. I've never been accosted by them, but I've seen the ruins of their determination to get at food in tents and coolers, and they've been known to kill pet dogs left out on a leash. So, again, it's good to be aware of one's surroundings while stargazing.

Image: Collared peccaries, also known as javelinas, are common night critters in far west Texas
(Credit: Brian Gratwicke posted on Wikimedia Commons)

But enough of these earthly matters - let's look at the summer night sky. As Earth orbits the Sun throughout the year, the night sky changes with the seasons as different parts are visible at different times of the year - the key words here being "night sky." Every day of the year, all the stars ever visible from any given location come into the sky - some are up at night and can be seen, while the rest are up during day but hidden by sunlight. So when we speak of the summer sky, we mean that part of the sky that's up during the early evenings of summer.

Image: The night sky changes with the seasons (diagram by author)

The Milky Way, the galaxy of which we are a part, stretches all the way around the night sky, so part of it is up every night of the year - but the summer sky gets the brightest part. Galaxies are huge disc-shaped clusterings of billions of stars swirling around a central bulge where stars are far more concentrated.

The Milky Way's center happens to be in the heart of the summer sky, in the direction of Sagittarius and Scorpius, the signature constellations of summer. Although intervening cosmic dust and gases prevent our actually seeing into the heart of the galaxy, it is still the brightest and most star-rich area of the Milky Way. Hundreds of globular clusters, special type of star clusters akin to mini-galaxies, swarm around the Milky Way's central bulge, thus most of them are also seen in the summer sky.

But while the summer sky has the better Milky Way, the winter sky has a somewhat greater concentration of the brightest stars, called 1st magnitude stars. Sagittarius and Scorpius have but one 1st magnitude star between them, and the entire summer sky has just seven scattered across the sky. The winter sky has nine 1st magnitude stars, seven of which are bunched within the Great Winter Arc Region. The winter sky also contains Sirius and Canopus, the night sky's two brightest stars.

There are other seasonal differences, but it should be pretty clear that the seasons are not the same when it comes to the night sky and stargazing. In upcoming Stargazer columns we'll be highlighting the major constellations of summer.

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May 25, 2012
Stargazer #581

June 2012

Your guide to the stars: You can use the chart as a guide when looking at the night sky. The chart shows the sky as it will be at 11:30 p.m. early in the month, 10:30 p.m. at mid-month, and 9:30 p.m. late in the month.

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 the "N" representing north is at the bottom as you hold it out in front of you. The center of the chart represents the portion of the sky you see if you look straight up.

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: 8:29 p.m. / June 15 - Sunrise: 6:23 a.m.; Sunset: 8:35 p.m. / June 30 - Sunrise: 6:27 a.m.; Sunset: 8:37 p.m. [Times exact for Waco, TX]

• Moon June 4: Full / June 11: 3rd Quarter / June 19: New / June 26: 1st Quarter

• Night Sky Events Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ. [** = don't miss events]
  4 Mon.: The full Moon, called the Flower Moon, Rose Moon, Strawberry Moon, and Honey Moon, aligns to create a morning partial eclipse of the Moon that favors the far southwestern U.S. Our central U.S., and further east, likely won't have much worth trying to see.
  ** 5 Tue.: Transit of Venus, when Venus, at inferior conjunction between the Sun and Earth, passes across the face of the Sun as seen from Earth.
  11 Mon. morning: The Moon is at 3rd quarter.
  12 Tue. morning: Jupiter passes 5 degrees to the lower right of the Pleiades star cluster near the eastern horizon 30-45 minutes before sunrise; binoculars will help with the Pleiades.
  17 Sun. morning: A thin crescent Moon has lots of company as it hovers low above the eastern horizon 30-45 minutes before sunrise; Venus is 6 degrees below the Moon near the horizon while Jupiter is 2 degrees to the Moon's upper right, and the Pleiades star cluster is 5 degrees to the upper left. Again, binoculars will help.
  19 Tue.: The Moon is new.
  20 Wed. morning: Venus is 3 degrees to the upper left of the reddish star Aldebaran low in the east 45 minutes before sunrise; Jupiter is 7 degrees above.
  20 Wed.: Summer solstice - the beginning of summer and longest day of the year in the Northern Hemisphere - and the opposite in the Southern Hemisphere.
  21 Thu. early evening: Four objects align low in the west an hour after sunset with the crescent Moon near the horizon; Mercury is 7 degrees to the upper right with Pollux is 5 degrees further to the upper right and Castor yet another 5 degrees. (Pollux and Castor are the Gemini Twins.)
  22 Fri. evening: For binoculars or telescopes: The darkened side of the crescent Moon passes within a hair of the star cluster M67 very low in the west at dark with the Beehive star cluster 8 degrees to their upper right.
  23 Sat. evening: The Moon is 8 degrees below the star Regulus, and then 10 degrees to the star's left the next evening.
  25 Mon. evening: The Moon is 8 degrees below Mars, and then 10 degrees to its left the next evening.
  26 Tue. evening: The Moon is at 1st quarter.
  27 Wed. evening: The star Spica is 5 degrees to the upper left of the Moon with Saturn another 5 degrees to the star's upper right in the southwest; all three will nearly fit within the same field of view of most 7X binoculars.
  30 Sat. evening: The Moon is 7 degrees to the upper right of the star Antares in the S.
  30 Sat. evening: Mercury, at its best for viewing, is at greatest elongation 26 degrees east of the setting Sun.
  

• 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: Mars, Saturn, Mercury (later in the month)
  Morning: Jupiter, Venus (later in the month)
  * Mercury starts the month in the Sun but quickly emerges low in the west; it spends the rest of the month in the evening sky, climbing highest from the setting Sun the last day of the month.
  * Venus begins the month in the Sun but soon emerges low in the east to begin its stint as the "morning star."
  * Mars, high in the southwest in the evening, sets in the wee hours of morning.
  * Jupiter begins the month rising at dawn but by month's end is well up in the east before dawn.
  * Saturn is high in the south in the evening and sets well before dawn.
  

• Transit of Venus
  June 5, from late afternoon until sunset, Venus passes directly across the face of the Sun - something that won't happen again until 2117 - but seeing this event requires the proper equipment to avoid permanent eye damage. Amateur astronomers in many areas will be setting up safe viewing sites so watch the media for locations. For viewing information in the Waco area, see TRANSIT VIEWING INFO elsewhere on this web page. To read more about the transit, see May 11, 2012: Transit of Venus immediately below.

• Circumpolar Region of Summer
  As Earth rotates on its axis, the North Star is always straight up from Earth's North Pole, hence the star's formal name, Polaris. And as Earth rotates, Polaris always appears in the same location while all the other stars rotate around it in a counterclockwise direction every 24 hours. [Technically, Polaris is almost exactly straight up, being less than 1 degree off. And the stars make one complete rotation every 23 hours and 56 minutes - a star (sidereal) day rather than a solar day. But those are topics for another time.]
  Two characteristics of Polaris' location led to its designation, many years ago, as "the most practically useful star in the heavens." First, owing to its being straight up from Earth's North Pole, it is, as every Boy and Girl Scout knows, always seen in the north from any place in the Northern Hemisphere. (It is of no help in the Southern Hemisphere as it is never visible from below the equator; and since there is no naked-eye star straight up from Earth's South Pole, there is no convenient South Star.)
  The second characteristic is less well-known but equally important. From any location in the Northern Hemisphere, Polaris' altitude above the horizon equals the latitude of that location. For example, from my home in Waco at latitude 31 degrees north, Polaris is always seen 31 degrees above our horizon. By measuring Polaris' altitude in degrees, explorers could determine their latitude. (Finding their longitude was more complicated and Polaris was of no help, but that's for another discussion.)
  The part of the night sky that rotates around Polaris and never goes below the horizon is called the Circumpolar Region. This region contains six constellations, at least part of which are always above the horizon: Ursa Major and Minor, Cassiopeia, Cepheus, Draco, and Camelopardalis.
  Ursa Major and Minor, the large and small bears, are better known by the unofficial patterns within each, the Big and Little Dippers. The Big Dipper is composed of relatively bright stars and is one of the best-known patterns in the Northern Celestial Hemisphere, although not all cultures see it as a dipper. Among the many visualizations are a plow, wagon, and bear being chased by three Indian braves.
  The Little Dipper is composed of mostly fainter stars and more difficult to make out, but its claim to fame is the star at the end of its handle - Polaris. This time of year during the evenings, the dippers are above Polaris, unlike the fall when they are below and near the northern horizon. From our more southerly latitudes, most of the Big Dipper even sinks just below the horizon for a time in the fall.
  Cassiopeia and Cepheus, the queen and king of the constellations, are on the other side of Polaris from the Big Dipper. They are lower and nearer the horizon during spring and summer evenings, but are prominent during the evenings of fall and winter.
  The long and winding Draco the dragon looks more like a cosmic snake. Even though most of his stars are not very bright, its fun to trace his pattern as he starts between the dippers, winds around the Little Dipper, and then turns his head back up toward the bright star Vega.
  The final Circumpolar Region constellation is Camelopardalis the giraffe. Although quite large, it is composed of such faint stars that it appears to be a virtually empty area of the sky - so don't waste your time trying to make out the constellation.
  Image: The diagram shows the Circumpolar Region as it appears in the early evenings of summer. The circle indicates the stars and constellations which never dip below the horizon from about latitude 30 degrees north.

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

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May 11, 2012
Stargazer #580

Transit of Venus

Come May 20 we will be treated to a relatively rare solar eclipse – a partial eclipse over much of the western half of the U.S. and an even more spectacular annular eclipse for the lucky ones in a 200-mile wide band stretching from the Texas panhandle to northern California. (For details, see Apr. 13, 2012: Solar Eclipse Coming Our Way below.)

On June 5 an even rarer event will be visible over the entire North American continent as millions of people – with safe and proper equipment – will be witness a transit of Venus. When the planet passes directly between the Sun and Earth, it appears as a tiny black dot creeping across the face of the Sun.

While the transit won't be as dramatic as the “ring of fire” of an annular eclipse, it is far rarer. Transits of Venus occur in 8-year-apart pairs with each pair occurring less than once each century. This 2012 transit is paired with the 2004 transit which didn't get as much notice since it was not positioned well for viewing in the U.S. The previous pair occurred in 1874 and 1882, and the next pair won't come around until 2117 and 2125 – long after we're gone, so it's now or never for us.

A transit and a solar eclipse are similar as both involve a solar system object passing between our planet and the Sun. Yet they are quite different in effect. With a solar eclipse, the Moon comes in between, and given its nearness to us, all or much of the Sun is dramatically eclipsed (covered) briefly. However, Venus, although larger than the Moon, is much further away and thus covers only a tiny percentage of the Sun, not even enough to be noticed by casual observers.

Venus Transits in History

Indeed, there is no known record of an observation of a transit of Venus until British astronomer Jeremiah Horrocks' accomplished the feat in 1639. In the early 1600s Johannes Kepler discovered that planetary (and other) orbits are elliptical rather than circular; he published his Rudolphine Tables of planetary motions in 1627 and predicted there would be a Venus transit in 1631. Unfortunately, he died in 1630, and the few others who knew about it were in the wrong part of the world to see it. Eight years later when the second of the paired transits occurred, Horrocks was one of only two – other being his friend, William Crabtree – who reported viewing the 1639 transit.

The next time around, in 1761 and 1769, astronomers were better prepared. And by then, thanks to British astronomer Edmond Halley (of Halley's Comet fame), they realized the potential scientific importance of Venus transits. Halley pointed out that if precisely measured from several different parts of the world, a far more accurate value for the mean distance between the Earth and Sun (a measure known as an “astronomical unit”) could be calculated using basic geometry.

Capt. Cook in Tahiti

During our recent trip to New Zealand, we spent four days in Tahiti on the way home. While on a tour around the scenic island, we made a stop at a place named Point Venus where there was a beautiful 1800s lighthouse. Almost casually the tour guide mentioned that it was also the site from which Capt. James Cook observed a transit of Venus in June 1769.

In 1760, the world powers, notably Britain and France, set out to organize expeditions in both 1761 and 1769 to make observations, one expedition being that of Cook and Charles Green to the South Pacific.

They benefited from cooperative weather and did indeed observe the transit, yet their measurements – like those of other expeditions – were confounded by unforeseen problems. A major issue was the blurring effect of Earth's atmosphere which made it difficult to ascertain the exact moment of Venus' contact with the edge of the Sun – and precision was essential to success. So the results of all these efforts, while not complete failures, were disappointing to the astronomical world. (The astronomical unit has since been measured with great accuracy by far more sophisticated means.)

Image: Engraving on this marker: “The people of Tahiti built this memorial to CAPT. JAMES COOK RN, who observed the Transit of Venus from near this site on 3 June 1769 during his first Pacific voyage, and gave the name Point Venus.” (photo by the author)

Seeing the Transit of Venus

At least part of the nearly seven-hour June 5 transit of Venus will be visible from the entire U.S., and like with the May 20 solar eclipse, the further west one is, the longer it will be visible. Most of the middle U.S. will see the first half before the Sun sets, but this should be enough to enjoy the view.

Two things to note about the following contact times – they are geocentric, calculated for the center of Earth, thus actual times for specific locations can vary a few minutes, and they are given in Central Daylight Time.

Venus first touches the edge of the Sun (Contact 1) at 5:10 p.m. and is totally within the Sun's disc (completely surrounded by sunlight – Contact 2) at 5:28 p.m. It reaches mid-transit at 8:30 p.m. which is around sunset for most of the central U.S. Although it will already be below the horizon for the continental U.S., Contact 3 and 4 occur at 11:32 p.m. and 11:45 p.m., respectively.

Image: 2004 Transit of Venus (from Wikimedia Commons)

The usual precautions about viewing the Sun apply to viewing transits as well as solar eclipses. In addition to visible light, the Sun emits invisible ultraviolet, infrared and other rays which, even if not painful at the moment, can still cause serious and permanent eye damage. As fascinating as transits and solar eclipses are, they not worth losing one's eyesight, so never view the Sun, even for a few seconds, without proper protection, such as approved solar glasses or #14 welder's glass.

The safest way to view the transit (and eclipse) is by using binoculars or a telescope – not to look through directly, but to project an image of the Sun on a piece of white cardboard. This is also a more fun method as a group can simultaneously watch the event. Venus' apparent diameter is only about 1/30 that of the Sun, so its silhouette will appear quite small, somewhat like a darker and perfectly round sunspot gradually easing across the Sun.

The Central Texas Astronomical Society will host a free public viewing in Waco for both the May 20 partial solar eclipse and June 5 transit of Venus – CLICK HERE FOR DETAILS. For other areas, check your local media as many amateur astronomy clubs will likely set up free public viewing sites.

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April 27, 2012
Stargazer #579

May 2012

Your guide to the stars: This chart shows the night sky as appears at 11:30 p.m. early in the month, 10:30 p.m. at mid month, and 9:30 p.m. late in the month from latitude 30ŗ 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
  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 5: Full / May 12: 3rd Quarter / May 20: New / May 28: 1st Quarter

• Night Sky Events [Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ.] [** = don't miss events]
  
  May 1 Sun.: May Day and Beltane, a cross-quarter day celebrating the middle of spring.
  4 Fri. all night: The nearly full Moon travels across the sky with the star Spica (nearest the Moon) and the planet Saturn (slightly brighter).
  5 Sat. morning: The Eta Aquarid meteor shower peaks but the Moon makes this an unfavorable year.
  5 Sat.: The full Moon is called the Milk Moon, Flower Moon, Corn Moon, and Planting Moon; as this full Moon occurs with the Moon at perigee (nearest Earth in its elliptical orbit) it will appear slightly larger than usual and will produce higher-than-average tides in coastal regions.
  6 Sun. evening: “Evening star” Venus passes less than two moonwidths to the lower left of the moderately bright star El Nath, the star marking the tip of the right horn of Taurus the Bull.
  12 Sat. morning: The Moon is at 3rd quarter.
  **20 Sun. evening: The new Moon produces a partial solar eclipse – see feature box.
  20 Sun. evening: Saturn passes above Virgo's brightest star Spica high in the south; for an added treat with binoculars, look for two fainter stars near creamy-colored Saturn – a white star to the upper right and reddish star to the upper left – both within a moonwidth of Saturn.
  22 Tue. early evening: A thin crescent Moon is to the left of Venus near the western horizon at dusk.
  28 Mon. evening: The 1st quarter Moon is below Mars high in the southwest with Leo's brightest star Regulus to their right.
  31 Thu. evening: Virgo's alpha star Spica is just above the waxing gibbous Moon with slightly brighter Saturn above Spica.
  Early Evenings: During the early evenings of May, the Milky Way lies flat around the horizon, making it seem to disappear.
  

• 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, Mars, Saturn
  Mornings: Mercury (early in month), Saturn (low)
  * Mercury starts the month low in the east before sunrise, sinks into the morning Sun's glare by mid-month, and passes behind the Sun at month's end.
  * Venus, still the brilliant “evening star,” begins the month high in the WNW after sunset; it then begins its rapid move toward the setting Sun and by month's end sets soon after the Sun.
  * Mars, high in the S in the evening, sets in the wee hours of morning.
  * Jupiter spends the month hidden in the glare of the Sun.
  * Saturn is well up in SE in the evening and sets before dawn.
  

• Solar Eclipse
  On May 20 just before sunset, the new Moon produces an annular eclipse visible within a narrow band from the northwest Texas panhandle to northern California and beyond. The rest of the western U.S. will see a partial solar eclipse just before the sun sets. For more information, see the previous Stargazer column below.

• Cosmic Baseball Region
  With the baseball season now underway, it's fitting that the Cosmic Baseball region is prominent in the early evening sky. It doesn't take much imagination to hear the fans cheering as the players round the bases – but perhaps your imagination needs a little help finding the bases.
  When I was a youngster growing up on Galveston Bay, my stargazing mentor, Margaret Willets, identified for me a popular informal pattern of four stars known as the Diamond of Virgo. Not an official constellation, its stars are from the constellations Bootes, Virgo, Leo, and Canes Venatici. But unfortunately, without Mrs. Willets, I just couldn't find the diamond on my own.
  Years later when I was learning the night sky in earnest, I still had trouble finding that elusive diamond – until I began thinking of it as a baseball diamond. With that visualization, my imagination filled out the entire playing field, creating the Cosmic Baseball region. It helped me learn the constellations of an entire section of the spring and summer night sky, and maybe it can help you too.
  While the Diamond of Virgo isn't a perfect square, it's close enough to use for our infield. Locate the Big Dipper high overhead and follow the arc of its handle three fist-widths (held at arm's length) to Arcturus (“arc to Arcturus”), a bright orange star now mid way up in the southeast. That's home place.
  Continue the arc another three fist-widths to Arcturus' lower right to the bright white star Spica, our first base. At Spica, turn left (up) and go just over three fist-widths to second base – the somewhat fainter star Denebola at the tail of Leo the Lion. Make yet another left turn and go three fist-widths to the upper left to third base, the even fainter star Cor Caroli situated beneath the arc of the handle of the Big Dipper. And that completes the infield of our cosmic baseball field. (We'll have to fill out the remaining outfield constellations another time.)
  Note that the planets Saturn and Mars, not ordinarily part of the Cosmic Baseball region, are passing through the playing field this year. Proceeding from Arcturus (home plate), and just before reaching Spica (first base), the creamy-colored Saturn slightly outshines first base. And two fist-widths beyond Denebola, in the outfield, is reddish Mars, now matching Arcturus in brightness as well as color.
  Keep in mind that throughout the night, and as the seasons progress, the entire Cosmic Baseball region gradually moves across the sky in a generally westward direction,. Spica, for example, is now seen in the south in the early evening, but later in the night it will be in the southwest, and by morning will be setting in the west. Still, the positions of the stars relative to each other, and the distances between them, won't change. So, batter up.
  Image: Cosmic Baseball Field and Diagram

• Astro Milestones
  May 18, 1910, Earth flew through the tail of Halley’s Comet, creating panic among the more gullible who bought gas masks and anti-comet pills to protect them from the “deadly gasses.” Imagine the panic the charlatans could have caused had they had today's Internet.
  

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Sat., May 12, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at dark. CTAS owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is also Sat., May 12, 8-10 p.m. See www.centexastronomy.org for more information.

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April 13, 2012
Stargazer #578

Solar Eclipse Coming Our Way

The May 20 new Moon will produce a solar eclipse visible over the western half of the U.S. Those in a narrow band from the Texas panhandle to northern California will see a rather rare annular eclipse while the rest of us will see an impressive partial eclipse around sunset.

As the Moon orbits our planet each month, the point at which it passes between the Sun and Earth is new Moon. If the plane of the Moon's orbit around Earth was exactly the same as the plane of the Earth's orbit around the Sun, we would see a total solar eclipse every new Moon (and a total lunar eclipse every full Moon). But since the two orbital planes aren't exactly the same, solar (and lunar) eclipses occur far less frequently.

When the Moon does pass exactly between the Sun and Earth, it can create a total solar eclipse, temporarily blocking out the Sun and casting a moving shadow across part of Earth. If it passes partly, but not quite exactly, between and blocks out part of the Sun, in creates a partial solar eclipse.

The Sun is 400 times larger than the Moon, and by coincidence, is also 400 times further away, thus they appear very nearly the same size. But since the orbits of the Earth and Moon are elliptical rather than circular, the distances between the Earth and Sun, and between Moon and Earth, vary making their apparent sizes change slightly.

Since the Moon's orbit around Earth is more eccentric (less circular) than Earth's orbit around the Sun, the change in the Moon's apparent size is more pronounced. When solar eclipses occur with the Moon further from Earth, the Moon isn't large enough to cover the entire Sun, leaving a “ring of fire” around the Moon's silhouette. What would otherwise be a total eclipse becomes an annular eclipse.

Image: When an eclipsing Moon isn't large enough to cover the entire Sun, the result is the “ring of fire” of an annular eclipse.
(Credit: sancho_panza / Wikimedia Commons)

This is what those within a narrow band less than 200 miles wide from Texas to California will see, weather permitting. At the extreme eastern end of this band in Texas, the eclipse will reach annularity just as the sun is setting. The further west from which one views, the earlier before sunset the eclipse begins and the longer it will be visible.

Image: Area from which the May 20 annular eclipse can be seen.
(Credit: Fred Espenak and Sky & Telescope)

The rest of the western U.S. not within the area of annularity will see a partial eclipse of the Sun where the Moon covers part of the Sun. The nearer one is to the area of annularity, the greater the percentage of the Sun will be eclipsed.

Image: Increasing amounts of partial eclipse leading toward an annular eclipse.

(Credit: Fred Espenak)

In Central Texas the partial eclipse begins at 7:35 p.m. with the Sun less than a fist-width (held at arm's length) from the western horizon. By sunset (8:21 p.m. in Waco), the Moon will be covering more than half of the Sun. Further east, the show will be shorter with less coverage; further west, longer and more coverage.

At the extreme eastern end, in the Lubbock area, the partial eclipse reaches annularity just as the Sun is setting. Further west, like in Albuquerque, the entire 4-minute period of annularity occurs just before the Sun sets. For points beyond the Nevada-Arizona-Utah border area, the entire eclipse – partial and annularity – will be visible before sunset.

It is essential to view this event safely. Even when partly eclipsed and near the horizon, the Sun can produce serious and permanent eye damage if viewed with without proper protection. Make-shift devices like stacked sunglasses, soot-covered glass, and CDs are not adequate; while they block out visible light, they don't protect against the invisible but more dangerous ultraviolet and infrared radiation. For direct viewing use approved solar glasses or #14 welders glass. Even safer is indirect viewing of projected images of the Sun using “pin-hole” projectors or binocular images cast on a sheet of white paper. Never look at the Sun with binoculars (or telescope) without using a proper solar filter.

Here's hoping for a cloudless western horizon May 20 before sunset. But even if you're clouded out, the event should generate some exceptional photos of the eclipsed Sun near the horizon, so watch the media for postings the next day.

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March 23, 2012
Stargazer #577

April 2012

Your guide to the stars: This chart shows the night sky as appears at 11 p.m. early in the month, 10 p.m. at mid month, and 9 p.m. late in the month from latitude 30ŗ 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
  Apr. 1 – Sunrise: 7:15 a.m.; Sunset: 7:48 p.m. / Apr. 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
  Apr. 6: Full / Apr. 13: 3rd Quarter / Apr. 21: New / Apr. 29: 1st Quarter

• Night Sky Events [Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ.] [** = don't miss events]
  
  ** Apr. 2 Mon. and 3 Tue. evenings: Venus grazes the beautiful Pleiades star cluster (AKA the Seven Sisters) and should create a beautiful sight with naked eyes and through binoculars.
  3 Tue. evening: The bright waxing gibbous Moon is 10 degrees below Mars.
  6 Fri.: The full Moon, called the Egg Moon, Grass Moon, and Easter Moon, is immediately to the right of Spica (nearest) and Saturn, although the Moon's glare will make seeing them challenging.
  13 Fri.: Friday the 13th, considered unlucky by the superstitious, comes around for the second of three 2012 occurrences, the last time coming in July.
  11–16 Wed.-Mon. evenings: Venus passes within 10 degrees to the right of the star Aldebaran and the V-shaped Hyades star cluster.
  13 Fri. morning: The Moon is at 3rd quarter.
  15 Sun.: Mars, having moved back to within 4 degrees of Regulus, resumes direct (eastward) motion (as seen against the background stars) and will again begin moving away from the star.
  15 Sun. all night: Saturn is at opposition – rising in the east at sunset and setting in the west at sunrise – and is at its nearest, brightest, and largest-appearing for the year.
  18 Wed. morning: Mercury is at greatest elongation 27 degrees west of the rising Sun. The crescent Moon is less than a fist-width (7 degrees) above the tiny planet, and the next morning an even thinner crescent Moon is one fist-width to the left – very low in the east as dawn breaks. Binoculars will help.
  21 Sat.: The Moon is new.
  22 Sun. morning: Lyrid meteor shower peaks with no Moon interference this year.
  22 Sun. early evening: The thin crescent Moon is 4 degrees above Jupiter near the west northwestern horizon at dusk.
  23 Mon. early evening: The crescent Moon is in Taurus with the Pleiades star cluster 6 degrees to its lower right and the star Aldebaran 8 degrees to its upper left – all near the west northwestern horizon as the evening sky darkens.
  24 Tue. early evening: Tonight the crescent Moon is now 7 degrees above Aldebaran with Venus 6 degrees to the Moon's upper right.
  29 Sun. evening: The Moon is at 1st quarter.
  30 Mon. evening: “Evening star” Venus is at its brightest at magnitude -4.5; other than fleeting events like fireball meteors, only the Sun and Moon outshine Venus.
  30 Mon. evening: Reddish Mars (left), the Moon (below), and the star Regulus (upper right) form a triangle high in the SSW.
  

• 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, Venus, Mars, Saturn
  Mornings: Mercury, Saturn
  * Mercury, low in the east all month, is at its best during mid-month.
  * Venus, the dominating “evening star” in the west, still sets nearly four hours after the Sun.
  * Mars is up most of the night, setting just before dawn.
  * Jupiter, low the west in the early evening, starts getting lost in the setting Sun by month's end.
  * Saturn, up by 9 p.m., is in the southwest by morning.
  

• Advance Notice
  It's now only 12 years until the Apr. 8, 2024, total solar eclipse passes over the U.S. from Texas to Maine.

• South Circumpolar Region
  
  [Image: South Circumpolar Region (from Wikimedia Commons]
  In the northern hemisphere we have a section of the night sky we call the Circumpolar Region consisting of those stars and constellations that never dip below the northern horizon as they circle the north celestial pole (and Polaris) each day. We should call it the North Circumpolar Region since the southern hemisphere has a comparable South Circumpolar Region consisting of the stars and constellations that never dip below the southern horizon as they circle the south celestial pole.
  And it is those stars, constellations, and other night sky objects of the South Circumpolar Region that we in the U.S. can't see from our mid-northern latitudes as they never rise above our horizon. Getting to see these hidden jewels is why we northern stargazers get excited about viewing below the equator in places like New Zealand. In a recent column, we cited some of these, like the Southern Cross constellation, stars Alpha and Beta Centauri, Canopus, and Achernar, and the Eta Carina Nebula.
  The South Circumpolar Region is also home to two small galaxies known as the Large and Small Magellanic Clouds. Although the explorer Ferdinand Magellan gets credit for “discovering” them in 1519, they were, of course, undoubtedly known to southern hemisphere natives long before the 16th century. But since neither they nor Magellan knew about galaxies at that time, the Europeans called them clouds and named them for Magellan.
  The LMC and SMC are each composed of millions of stars and are believed to be companion galaxies gravitationally bound to our much larger Milky Way Galaxy. Whereas the Milky Way is 100,000 light years in diameter, the LMC is 33,000 light years and the SMC 20,000 light years in diameter. The LMC is 163,000 light years away and the SMC 196,000 light years distant – quite close compared to the Andromeda Galaxy's distance of 2+ million light years.
  Easily visible to the naked eye under dark skies, they appear like cosmic clouds, hence their names. Being galaxies, it's not surprising that they look like someone took two patches out of the Milky Way and placed them some distance away. The LMC spans some five degrees with the SMC half that size. (Your fist held at arm's length is about 10 degrees wide.)
  Ironically, the Southern Circumpolar Region, which we never see, is always visible to most residents of the southern hemisphere all night and throughout the entire year, just as the Northern Circumpolar Region is always visible to us. And while in New Zealand, I was reminded by fellow stargazer Gary Roberts, who has lived in New Zealand all his life, that they never see the stars, constellations, and other night sky objects in the North Circumpolar Region. He lamented that has never seen the Big Dipper, Cassiopeia, Polaris, or even the Andromeda Galaxy.

• Astro Milestones
  * April 12 is the 51st anniversary of Yuri Gagarin's 1961 historic 108-minute orbital flight around Earth – the first for humankind.
  * April 21 is the 50th anniversary of the 1962 landing of Ranger 4, the first American spacecraft on the Moon. Intended to soft-land scientific instruments on the lunar surface, a malfunction caused the craft to crash-land, but even that was progress as previous attempts had missed the Moon entirely.
  * Apr. 25, 1990, the 8-foot (in diameter) Hubble Space Telescope was deployed by Discovery space shuttle astronauts, but the almost-immediate discovery of defective optics was met with bitter disappointment. Thanks to some ingenious scientists, engineers, and astronauts, corrective optics were installed in 1993, and to this day astronomers are using HST to make remarkable discoveries. And its thousands of images of our cosmos continue to dazzle us like no other scientific instrument.
  

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Sat., April 14, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at dark. CTAS owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is also Sat., Ap;ril 14, 7-9 p.m. See www.centexastronomy.org for more information.

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March 9, 2012
Stargazer #576

More Stargazing Below the Equator

This column, like the previous two, comes to you from the small but fascinating country of New Zealand situated deep in the Southern Hemisphere nearly a thousand miles southeast of Australia. The natural beauty, rich diversity of scenery, and many other factors (like friendly people and no snakes or poison ivy) make this land a virtual paradise.

And for stargazers, getting to see stars, constellations, and other night sky objects in the Southern Celestial Hemisphere is a thrill. But as reported last time, I've been frustrated by cloudiness and have to keep reminding myself that the Maori – the Polynesians who first settled the islands nearly a thousand years ago – named it Aotearoa, "land of the long white cloud." And it's the rains from the clouds that give so many places in New Zealand a lush tropical rain-forest feel. Still, I'd sure like more clear nights.

Image: Clouds like these over New Zealand's Southern Alps mountains suggest why the Maori called the land
Aotearoa, the “land of the long white cloud.” (photo by author)

One clear evening I did get to set up my wife's spotting scope (which she uses for birds) in the parking lot of a back packer (hostel) in which we were staying. Before long a small group assembled and we had a spontaneous mini-star party with folks from Canada, England, Holland and the U.S. When I pointed out Venus and Jupiter, the young man from Holland expressed surprise that the planets could also be seen from “down” here.

It gave me an opportunity to explain about the Sun's path across the sky (called the ecliptic), and how the Moon and planets also follow the same path as they move through the sky. And just as the Sun can be seen from all places on Earth, so can the Moon and planets. Owing to the Earth's west-to-east rotation on its axis, the Sun, Moon and planets all rise in the east and set in the west above and below the Equator.

Image: Venus (lower left) and Jupiter setting at dusk over the Coromandel Peninsula
on the eastern coast of New Zealand's North Island (photo by author)

Still, there are differences. From the Northern Hemisphere, the ecliptic tilts toward the south whereas in the Southern Hemisphere it tilts toward the north, and that can be disorienting. When we in the north see the Sun move across our sky each day, we're facing in a southerly direction, and the Sun moves left-to-right across our sky. And it's the same with the Moon and planets at night.

However from the Southern Hemisphere and facing in a northerly direction, they move right-to-left – backward from what we're used to. Even during the day this is confusing: we're accustomed to seeing the morning Sun to our left and the afternoon Sun to our right, and can almost unconsciously estimate the approximate time of day with a quick glace at the Sun's location. But here, we northerners have to consciously remember to reverse things in our mind and realize that the morning Sun will be to our right and the afternoon Sun to our left.

There is also another difference. As mentioned previously, most constellations can be seen from both the Northern and Southern Hemisphere, yet when seen from south of the Equator, they appear upside-down to us northerners. And it's the same with the Sun, Moon, and planets – they too appear upside-down. While that's not noticeable with the Sun and planets (viewed naked-eye), the full Moon's “man in the Moon” is hard to make out as he too is upside-down.

And there are yet a couple of other notable departures from what we're used to seeing. In the Northern Hemisphere, circumpolar stars and constellations rotate around the North Star (Polaris) in a counterclockwise direction whereas in the Southern Hemisphere they rotate clockwise – and they rotate around an essentially empty space in the night sky.

By chance, we have a reasonably bright star – a star we have named Polaris (the North Star) – almost straight up from Earth's North Pole. But in the Southern Hemisphere they're not so lucky as there is no bright star straight above the South Pole, and hence no South Star.

On another note, I had an interesting experience while walking in a small town. A passing stranger looked at my t-shirt, smiled big, and gave me a thumbs-up. At first I was puzzled, but quickly realized I was wearing my “Bring back Pluto” t-shirt. I guess Pluto-lovers are found around the world.

A final issue not related to stargazing is worth mentioning. After our 2001 trip to New Zealand, I was asked if I noticed water draining down basins and toilets in a reverse direction. In fact, that popular notion is a myth. A phenomenon called the Coriolis effect, caused by the rotation of the Earth, does affect large-scale systems like hurricanes which rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

But the effect is far too weak to influence the rotational flow of things in our every-day life, like water down drains, except under highly controlled laboratory situations. Other factors – like the direction from which the water enters a toilet or basin or other subtle currents within the water – determine the direction of rotation. If you make it a point to notice such things, you'll find clockwise and counterclockwise motions occur with about equal frequency.

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February 24, 2012
Stargazer #575

March 2012

This chart shows the night sky as appears at 10 p.m. (CST) early in the month, 10 p.m. (CDT) at mid month, and 9 p.m. (CDT) late in the month from latitude 30ŗ 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
  Mar. 1 – Sunrise: 6:56 a.m.; Sunset: 6:27 p.m. (CST) / Mar. 15 – Sunrise: 7:39 a.m.; Sunset: 7:37 p.m. (CDT) / Mar. 31 – Sunrise: 7:19 a.m. Sunset: 7:47 p.m. (CDT) [Times exact for Waco, TX]

• Moon
  Mar. 8: Full / Mar. 14: 3rd Quarter / Mar. 22: New / Mar. 30: 1st Quarter

• Night Sky Events [Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ.]
  
  3 Sat. all night: Mars reaches opposition – opposite the Sun as seen from Earth – which it does every other year. It will pass nearest Earth at 63 million miles and, reaching magnitude -1.2 , will gleam like a reddish Sirius (the night-sky’s brightest star). This year Mars comes to opposition during the month named in its honor.
  5 Mon. evening: Mercury, at highest from the setting Sun for this apparition, is seen low in the west at dusk.
  7 Wed. evening: Mars is 10 degrees to the upper left of the Moon; owing to the red planet's current brilliance, it should stand out well against the usually overpowering glare of the nearly full Moon.
  8 Thu.: This full Moon is called the Lenten Moon, Sap Moon, Crow Moon, and Worm Moon.
  10 Sat. evening: After they rise ~9:30 p.m., the gibbous Moon (low in the east southeast), the star Spica (above), and Saturn (to their left) form an equilateral triangle 6 degrees on each side.
  ** 12 & 13 Mon. & Tue. evenings: Brilliant Venus and bright Jupiter pass within 3 degrees.
  14 Wed. morning: The Moon is at 3rd quarter.
  20 Tue.: Spring equinox – the beginning of spring in the Northern Hemisphere when day and night are of (almost) equal length.
  22 Thu.: The Moon is new.
  25 Sun. evening: The crescent Moon is 3 degrees to the upper right of Jupiter in the west.
  26 Mon. evening: The crescent Moon is 3 degrees to the upper left of Venus in the west.
  27 Tue. evening: Venus is at its farthest from the setting Sun for this “evening star” appearance and is up for nearly four hours after sunset.
  27 Tue. evening: The crescent Moon, passing through Taurus, is between the star Aldebaran (upper left) and the Pleiades star cluster (lower right).
  30 Fri. evening: The Moon is at 1st 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.]
  
  Evenings: Mercury (early in month), Venus, Jupiter, Mars, Saturn (late evening)
  Mornings: Saturn, Mars
  * Mercury, low in the west early in the month, is lost in the Sun's glare by mid-month.
  * Venus, still the brilliant “evening star” in the west, sets nearly four hours after the Sun.
  * Mars is up all night and at its nearest and brightest this month.
  * Jupiter, in the west in the evening, teams up brilliantly with Venus at mid-month.
  * Saturn, up well before midnight, is high in the southwest by morning.
  

• Time Change
  March 11 at 2 a.m. we set our clocks forward (“spring forward”) to Daylight Saving Time. (In fact, no time is saved – only lost as we annoyingly have to change our clocks and watches twice each year.)

• Southern Ship Region
  
  The Southern Ship Region, while occupying a reasonably large area, is not well-known and contains no familiar constellations. It does, however, relate to a story from Greek mythology that has been chronicled in books and movies.
  The Greeks regarded this region as one huge constellation, Argo Navis, the ship of the mythological Jason and this Argonauts. According the Richard Hinckley Allen in his 1899 classic book, Star Names: Their Lore and Meaning, the ship “carried the famous expedition...in search of the Golden Fleece, and when the voyage was over the goddess Athene placed the boat in the sky.”
  Finding the ship's region isn't difficult thanks to the hunter and his big dog. Orion is now high in the southwest in the early evenings prominently displaying his famous three-star belt while Canis Major is to his lower left and hard to miss being the home of Sirius, the brightest star in the night sky. The Southern Ship begins just beyond Canis Major – to the east (left), southeast (lower left), and south (below).
  In more recent times, the great ship has been partitioned into four constellations representing four parts of the ship, and unfortunately identifying those constellations isn't easy. Nearest to Canis Major is Puppis, the Ship's Stern. For ye landlubbers, the stern is the ship's rear section; its bow (front) isn't visible and has no constellation. Further to the southeast, and partly below the horizon, is Vela, the Ship's Sails. Both Puppis and Vela have several fairly bright stars, but being so low and near the horizon they don't stand out well.
  Most of Carina, the Ship's Keel, is too far south to ever be seen from our mid-northern latitudes, yet its brightest star, Canopus, makes a brief appearance for a few hours from the more southerly parts of the U.S. this time of year. For those living below the latitude of the Red River, Canopus, the night sky's second brightest star, rises a few degrees above the southern horizon just after dark.
  The fourth part of the ship is Pyxis, the Mariner's Compass, but don't bother looking for this small, faint and quite unremarkable constellation.
  There is yet one more constellation – not considered part of the ship by the Greeks, but one that I've added because it needed a region to call home – Antlia, the Air Pump. As told to me by a salty old Greek sea-dog, the ship's crew included an ambitious and creative, but not-so-bright, young Argonaut unfamiliar with the physical laws regarding equal and opposite forces. Thinking he would score big with Captain Jason, he stowed away an air pump to bring out when the mighty ship was stilled by a period of windless calm. Antlia is also small and faint, and like Pyxis, one of the constellations I call a “forgetum” – so faint and devoid of interesting objects that casual observers can ignore them.
  Unless you live in the lower part of the U.S., you might decide to regard this entire region as a forgetum, however, if it's within your reach, it does contain some jewels worth seeking out.
  [Image: Great Winter Arc Region (author's diagram)]

• Astro Milestones
  * March 13, 1781, William Herschel discovered the planet Uranus from Bath, England.
  * March 14 is the birthday of German-American physicist Albert Einstein (1879-1955).
  * March 17, 2011, NASA's MESSENGER spacecraft, launched in 2004, began its orbital study of Mercury which is still on-going.
  * March 23, 2012, is the 100th birthday of German rocket scientist Werner von Braun (1912-1977), who in one lifetime personified the worst and the best of science's potential. His V-2 rockets, built partly with slave labor, enabled Nazi Germany to bombard London and other European cities, killing countless innocents during WWII. After the war, his rockets launched the U.S. space program and eventually put humans on the Moon.
  
  Image: Rocket expert Werner von Braun standing in front of huge NASA rockets (NASA)

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

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February 10, 2012
Stargazer #574

Stargazing Below the Equator

This column comes to you from beautiful New Zealand deep in the Southern Hemisphere where my wife and I, along with two other couples, have just begun a six-week adventure in what many, including myself, consider the most beautiful and fascinating country in the world. And upon crossing the Equator, we went from the middle of winter to the middle of summer.

New Zealand is situated nearly a thousand miles southeast of Australia and consists mainly of two long, narrow islands sitting end to end – the North Island and South Island – and extending nearly one thousand miles. The islands are separated by Cook Strait that took our inter-islander ferry three hours to cross. To the east is the dazzlingly aqua-blue Pacific Ocean and to the west the Tasman Sea. Christchurch, the South Island's largest city, is a major point of departure for flights to Antarctica.

New Zealand's total land space is about equal to that of Colorado. Most of its 4.4 million residents reside within its five major cities, so there's lots of sparsely populated areas – especially on the South Island. For stargazers that means many areas with dark skies free of light pollution.

Its highly varied land consists of miles (they use kilometres) of coasts, beaches, ¨sounds, mountains, pastures, farm land, lakes, rivers, waterfalls, forests, and even ¨glaciers. But the beauty comes with a price. Situated where two tectonic plates meet, it also ¨has earthquakes, as Christchurch has been painfully aware this past year, and volcanoes, of which most, but not all, are extinct. ¨

The native Maoris of ¨Polynesian origin settled the islands less than a thousand years ago while Europeans, mostly English, began settling in the 1800s. Today, Maoris ¨represent less than 20 percent of the population, yet their ¨culture – language, art, names of rivers, lakes, towns and the ¨like – is a highly visible part of the fabric of New Zealand society, ¨similar to native American culture in Oklahoma, New Mexico, and Arizona. English ¨is the primary language, but Maori is also still in use.

A thumbnail sketch of New Zealand would be incomplete without mentioning the friendliness of the people – Kiwis as they call themselves, nicknamed after the kiwi bird. Their friendliness is more proactive and helpful than mere politeness, and it is contagious. Although I'm generally friendly by nature, I found myself seeking opportunities to be even more friendly and helpful to others.

An example of Kiwi friendliness: As I was changing a flat tire in a parking lot at the Auckland StarDome Planetarium, an older fellow stopped and asked if I needed anything. When I told him I could change the tire, but I had no idea where to get it fixed, he pointed me in the right direction. Later, after the tire shop replaced the tire, I asked the owner-manager the best way to get back to the hostel in which we were staying which was several kilometers away. Rather than simply give me directions, he got on his computer, had MapQuest calculate the route, and printed a map for me.

Unfortunately, I still got lost, but it wasn't his fault. I blamed it on having to concentrate so intently on New Zealand's English-style driving – traveling on the left side of the roads while seated on the right side of the auto. And, of course, I also blamed the “backward” driving for my whacking a curb which damaged the tire in the first place.

So what about stargazing, my primary reason for returning to this wonderful place? Well, so far it's been frustratingly limited owing to cloudy nights and the light-polluted cities we've been in most nights. But I have had one good, if brief, night of viewing, and though I saw nothing I didn't see during our previous trip to New Zealand in 2001, I was still thrilled.

Facing north I saw many of the constellations we see from home when facing south in the early evening this time of year – what we call the winter sky. I saw the constellations of the Great Winter Arc like Orion, Canis Major, Taurus, and Gemini. But even though they are familiar, they don't look like what we're used to seeing since from here they appear up-side-down. There's just nothing like seeing the great hunter standing on his head or the big dog on his back with his feet up.

Facing south and peering into the part of the sky never visible from our mid-northern latitudes, I immediately spotted the four stars forming the Southern Cross, the signature constellation of the Southern Hemisphere. It is so small your fist held at arm's length will cover it, yet it is usually the first thing that comes to mind when we think of the deep southern night sky. Both the New Zealand and Australian flags feature this four-star pattern.

To its lower right were Alpha and Beta Centauri, the brightest stars in the constellation Centaurus, most of which is hidden from our northern view. Alpha Centauri is noteworthy for being our nearest stellar neighbor at a mere 4 light years away. It is actually a multiple star system consisting of Alpha Centauri and several other fainter stars bound together by gravity and orbiting each other.

High overhead I saw two stars that we can see from the southern U.S., but just barely – Canopus in the constellation Carina, and Achernar in Eridanus. Canopus, which rises a few degrees above our horizon, was a major guide stars for Polynesian sailors who long ago navigated the huge Pacific using the stars. They undoubtedly used Canopus when they discovered New Zealand. Achernar just barely rises above our horizon.

In seeing part of the Milky Way too far south to reveal itself to us in the U.S., two jewels came into view. The Eta Carina Nebula, a naked-eye area of nebulosity (cosmic cloudiness), is formed by the incredibly huge dying star Eta Carina. The star itself isn't visible, but the nebula is spectacular. The other is a naked-eye star cluster, formally designated IC 2602, but better known as the Southern Pleiades. As is often the case with naked-eye objects, both are even more dramatic through binoculars.

While I saw several other things that first night, I'll save them for another column when there will be even more observations and reflections to report.

Image: The New Zealand flag features the Southern Cross (photo by author)

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January 27, 2012
Stargazer #573

February 2012

This chart shows the night sky as appears at 9:30 p.m. early in the month, 8:30 p.m. at mid month, and 7:30 p.m. late in the month from latitude 30ŗ 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
  Feb. 1 – Sunrise: 7:21 a.m.; Sunset: 6:03 p.m. / Feb. 15 – Sunrise: 7:10 a.m.; Sunset: 6:15 p.m. / Feb. 29 – Sunrise: 6:56 a.m.; Sunset: 6:28 p.m. (Times exact for Waco, TX)

• Moon
  Feb. 7: Full / Feb. 14: 3rd Quarter / Feb. 21: New / Feb. 29: 1st Quarter

• Night Sky Events [Held at arm's length, the width of your fist is 10ŗ and the width of your index finger is 1ŗ. The width of a full Moon is ½ŗ.]
  
  Feb. 2 Thu.: Groundhog Day and Candlemas, a cross-quarter day celebrating the middle of winter; and whether or not the groundhog sees his shadow, there will be 46 more days of winter.
  2 Thu. evening: The gibbous Moon is in Taurus the Bull, between the Pleiades star cluster and the star Aldebaran, the bull's red eye, high overhead.
  7 Tue.: The full Moon is called Wolf Moon, Snow Moon, and Hunger Moon.
  9 Thu. evening: Brilliant Venus passes less than a moonwidth to the right of much fainter Uranus low in the west; seeing Uranus requires at least binoculars.
  9 Thu. evening: After they rise ~8 p.m., the bright gibbous Moon is one fist-width (held at arm's length) to the right of reddish Mars which has brightened notably since the beginning of the year.
  12 Sun. late evening: After they rise ~11 p.m., the gibbous Moon is six moonwidths to the upper right of the star Spica which itself is twice that far to the upper right of slightly brighter Saturn; by morning the trio will high in the south.
  14 Tue. morning: The Moon is at 3rd quarter.
  15 Wed. morning: The Moon is one-half a fist-width above the reddish star Antares low in the south southeast.
  21 Tue.: The Moon is new – between the Earth and Sun.
  22 Wed. early evening: Soon after sunset, the very thin crescent Moon is one-half a fist-width to the right of Mercury very low in the west with brilliant Venus looking down from three fist-widths above; binoculars will help with Mercury.
  25 Sat. evening: The crescent Moon passes to the upper right of Venus in the west.
  26 Sun. evening: The crescent Moon passes to the lower right of Jupiter in the west.
  29 Wed.: Leap Day is inserted every four years to account for the fact that a year is actually 365¼ days, thus 2012 has 366 days rather than the usual 365.
  29 Wed. evening: The Moon is at 1st quarter.
  Note: Under clear, dark, moonless skies, late February is a good time to see the zodiacal light in the west for a couple of hours after evening darkness, and gegenschein (counter-glow) high above around midnight. Both appear as soft glows resulting from sunlight reflected off meteoric dust in the plane of our solar system.
  

• 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, Mars (late evening), Mercury (latter part of month)
  Mornings: Saturn, Mars
  * Mercury starts Feb. in the Sun, then emerges in the evening low in the west by mid-month.
  * Venus is the brilliant “evening star” in the west setting three hours after the Sun.
  * Mars is up at 9 p.m. and is high in the southwest in the morning.
  * Jupiter, in the west in the evening, sets by midnight.
  * Saturn is up by midnight and high in the south southeast in the morning.
  

• Great Winter Arc Region
  
  The Great Winter Arc region, prominent in the evening from December through April, contains more bright stars than any other comparable region seen from our mid-northern latitudes. But on those seemingly quiet, cold winter evenings, the region is far from tranquil. Its centerpiece, the great arc spanning more than 80 degrees (eight fist-widths held at arm's length) from the star Sirius to the star Capella, is separating two combatants from some other hostile critters.
  Within the arc are Orion the Hunter and Taurus the Bull, both looking ready for combat. Orion, with a raised club and shield, is face-to-face with the angry red-eyed, long-horned Taurus who, one can easily imagine, is snorting fire.
  Accompanying the hunter are his two canine companions, Canis Major and Minor. Their howls and snarls pierce the night as the big dog, reared up on his hind legs, is attempting to attack poor Lepus the rabbit hiding beneath Orion.
  The arc shields Orion and Taurus from some the region's other not-so-gentle creatures. Lynx the wild cat is perched in a tree waiting to pounce from above while Hydra the water snake slithers up from behind, intending to devour the small dog. Above the snake Cancer the crab wants to sink its sharp pinchers into someone, and hidden within Cancer the Beehive star cluster is swarming with killer bees.
  Just inside the arc seemingly observing all the action with a cautious eye are Gemini the Twins and Auriga the Charioteer. Two final guys seem totally out of place given all the region's hostilities. Cowering between the dogs, virtually invisible, is the usually playful Monoceros, the mythical unicorn. And below the rabbit is Columba the Dove facing what must seem like a Sisyphean challenge of bringing peace to the region.
  Bet you had no idea this part of the winter sky was so full of activity.
  Image: Great Winter Arc Region (author's diagram)

• Astro Milestones
  * Feb. 4 is the birthday of American astronomer Clyde Tombaugh (1906-1997) who discovered Pluto.
  * Feb. 15 is the birthday of Italian mathematician and astronomer Galileo Galilei (1564-1642).
  * On Feb. 17, 1600, Giordano Bruno was burned at the stake by the Inquisition for espousing heretical cosmological and religious views.
  * Feb. 19 is the birthday of Polish astronomer Nicolaus Copernicus (1473-1543) whose thesis that the Sun rather than the Earth is at the center of the universe revolutionized scientific and theological thinking in the western world.
  * Feb. 20, 1962, astronaut John Glenn became the first American to orbit Earth in his Mercury spacecraft named Friendship 7.
  

• Discovery of Pluto
  On Feb. 18, 1930, 24-year old Clyde Tombaugh discovered Pluto from Lowell Observatory near Flagstaff, Arizona. Using two photographic plates he had taken Jan. 23 and 29 of the exact same area of the sky, he noted a tiny point of light had moved from one location to another on the images taken a week apart. Upon further analysis, he realized he had discovered what was regarded as the ninth planet – a designation it held until August 2006 when the International Astronomical Union redefined “planet” and Pluto was reclassified as a dwarf planet, comparable to a large asteroid.
  Pluto is the only traditional planet never visited and studied up close by our spacecraft, but that's about to change as NASA's New Horizons, launched January 19, 2006, is on its way to a Pluto rendezvous in 2015. (Ironically, Pluto was still a planet when New Horizons left Earth.) Tombaugh died in 1997, and many who hold him in high regard, myself included, are deeply pleased that he will posthumously visit his beloved Pluto as some of his ashes are on board the New Horizons spacecraft. Bon voyage, Mr. Tombaugh.

  Image (left): Telescope with which Clyde Tombaugh took photos on which he discovered Pluto in 1930 at Lowell Observatory in Flagstaff, AZ (photo by the author)
  Image (right): New Horizons spacecraft to fly by Pluto in 2015 (NASA artist)

• Star Parties
  The Central Texas Astronomical Society's simultaneous free monthly star parties are Sat., Feb. 11, at the Lake Waco Wetlands, Belton's Overlook Park on Stillhouse Hollow, and Hubbard City Lakes Park beginning at dark. CTAS owns and operates the Meyer Observatory at the Turner Research Station near Clifton, TX; the next monthly observatory open house is also Sat., Feb. 11, 6-8 p.m. See www.centexastronomy.org for more information.

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January 13, 2012
Stargazer #572

2012 Night Sky Highlights

The coming year offers many stargazing delights, and a couple of them don't even occur at night. There will be the usual annual meteor showers, brilliant naked-eye planets, and pairings of night sky objects, but 2012 also will treat us to a partial solar eclipse and a rare transit of Venus.

Meteor showers. Meteor showers are annual events with the same showers occurring each year, but the presence or absence of a bright Moon determines which might be worth seeing in a given year. This year the Moon favors the Lyrids in April, the popular Perseids in August, the Draconids and Orionids in October, the Leonids in November, and the Geminids and Ursids in December. While more meteors are usually seen in the morning, this year the Perseids, Draconids, and Geminids might be entertaining throughout the night.

Naked-eye Planets. Each of the planets has its own schedule for favorable viewing times and dates, and these change from year to year. Speedy Mercury, which makes four trips around the Sun each Earth-year, usually makes six appearances in our night sky each year, each lasting two to three weeks with half in the morning, half in the evening. This year's morning appearances come in mid April (poorest), mid August (good), and late November-early December (best) when the elusive planet is seen low in the east for an hour or two before dawn. Evening shows will be early March (best), mid June (good), and most of October (poorest) when Mercury is seen low in the west for an hour or two soon after dusk.

Unlike the shy Mercury, Venus dominates the sky when she is up. This year the goddess of love and beauty will continue as the brilliant “evenings star” through mid May. After a rare encounter with the Sun in June – see below – she then becomes the “morning star” from July through the end of the year.

Mars will be a fixture in our evening sky much of the year. Currently rising in the late evening, it reaches opposition March 3, when is rises at sunset and is up all night. It will continue its evening presence until late December. For morning stargazers, Mars will also continue to be seen in the west in the morning sky for a few more weeks.

Jupiter, currently high and bright in the south in the early evening, will stay in the evening sky through April. Then after passing behind the Sun, it emerges in the morning in June, there to remain visible through late November. In October it also starts showing in the evening sky, reaches opposition December 2, and then dominates the evening sky through the end of the year.

Saturn now graces the morning sky high in the south, and will be visible in the morning through March. It also begins appearing in the evenings in March, reaches opposition April 15, and will be prominent in the evening sky until September. After passing behind the Sun in late October, it closes out the year back in the morning sky starting in November.

Close encounters. Every year gives us some pretty neat encounters between stars, planets, the Moon and other objects, and 2012 seems better than average. The encounter I'm most looking forward to is in mid March when the two brightest planets, Venus and Jupiter, pass within a few moonwidths of each other in the early evenings. If you like night-sky drama start watching them each evening as they gradually approach like two shy lovers, until they blaze side-by-side low in the west, and then part.

Solar eclipse. The solar eclipse occurs the late afternoon of May 20 and those directly in the eclipse path from around Midland, TX, northwestward through northern California will see an annular solar eclipse as the Moon passes exactly between the Sun and Earth. Ordinarily this would produce a total solar eclipse where for a few minutes the Moon would completely hide the Sun. However, owning to their relative distances during this eclipse, the Moon won't appear quite large enough to hide the entire Sun, but rather will cover the center, leaving a brief but dramatic “ring of fire.”

Those of us in the western half of the U.S. not in the less-than-200-mile-wide annular eclipse path will still see a nice partial eclipse low in the west shortly before sunset – and a partial eclipse at sunset with the Sun near the horizon could be pretty dramatic. From Central Texas, we will see the early stages of a partial eclipse for about 45 minutes before the Sun sets. The further northwest one is, the earlier before sunset the eclipse begins, and longer it will be visible.

Transit of Venus. By far, the rarest event of the year is the transit of Venus when our neighboring planet passes directly between the Sun and Earth. Unlike solar eclipses where the Moon noticeably hides part or all of the Sun for a few minutes, Venus is so far away that the transit is visible only through a telescope where Venus appears as a tiny black dot slowly moving across the face of the Sun. At least part of the nearly seven-hour transit will be visible from virtually the entire U.S., and like with the eclipse, the further west one is, the longer it will be visible. From Central Texas, we'll see the first three hours before the Sun sets, but this should be enough to enjoy the view.

Venus transits occur only twice per century, coming in pairs eight years apart. The last one was in 2004, so try to catch this one as there won't be another in our lifetime. The Central Texas Astronomical Society will likely have some properly solar-filtered telescopes set up for public viewing, so watch for announcements.

As the dates approach for these and other night sky events, keep reading this twice-monthly “Stargazer” column for more details about when, where, and how to look for them.

Of course, I needn’t have mentioned any events occurring after Dec. 21, 2012, since, according to the crackpots, the world will end and we won't be here to see anything.

Image: 2004 Transit of Venus (from Wikimedia Commons)

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