Non-Profit Internet Source for News, Events, History, & Culture of Northern Frederick & Carroll County Md./Southern Adams County Pa.

 

The Sky of February

Dr. Wayne Wooten
Professor of Astronomy
Escambia Amateur Astronomers' Association

For February 2009, the Moon will be a waxing crescent as the month begins, having passed three degrees north of brilliant Venus on January 30th. The next two weeks find the moon waxing in the evening sky. First quarter moon sits high in the sky and half-lit at sunset on February 2nd. The full moon is on February 9th and in folklore, is the Wolf or Hunger Moon. The waning gibbous moon on February 11th passes 5 degrees south of now almost ringless Saturn, with both rising about 7:30 PM in the east. Third quarter moon is on February 16th, and the waning crescent moon passes Mars and Jupiter in morning twilight on February 23, two days before new moon.

While the naked eye, dark adapted by several minutes away from any bright lights, is a wonderful instrument to stare up into deep space, far beyond our own Milky Way, binoculars are better for spotting specific deep sky objects. For a detailed map of northern hemisphere skies, about February 1st visit the www.skymaps.com website and download the map for February 2008; it will have a more extensive calendar, and list of best objects for the naked eyes, binoculars, and scopes on the back of the map. Also available as the next month begins is wonderful video exploring the February 2009 sky, featuring many different objects, available from the Hubble Space Telescope website at: http://hubblesite.org/explore_astronomy/tonights_sky/.

Venus dominates the evening sky and puts on an interesting telescopic display this month. Telescopically Venus appears on the edge of her orbit, 47 degrees east of the Sun as the month begins, and shows a disk that is 40% illuminated and 30° of arc across. By Valentine’s day, the goddess of love has proven fickle, changed directions, and started retrograding back westward toward the Sun. She is passing between us and the Sun, and on the 14th appears as a crescent, 31% in sunlight, but now grown to 36° of arc as she approaches us. By month’s end, her crescent is visible even in hand held binoculars, and is now 20% sunlit, and up to 45° of arc wide. She actually passes well north of the Sun into the morning sky at inferior conjunction on March 27th; for several days she will be visible as a very slender crescent right after sunset, then just before the dawn, a rare event made easier to observe for us since she lies so far north of the Sun this time. It was Galileo in 1611 who noted that Venus goes through this entire phase cycle, and correctly deduced this proved she orbited the Sun, not us. Covered with sulfuric acid clouds, her bright disk reveals only her phase, with no visible cloud details in the scopes. My photo of crescent Venus in July 2007 shows how she will look in small telescopes as February ends.

The constellation Cassiopeia makes a striking W in the NW. She contains many nice star clusters for binocular users in her outer arm of our Milky Way, extending to the NE now. Her daughter, Andromeda, starts with the NE corner star of Pegasus’‘ Square, and goes NE with two more bright stars in a row. It is from the middle star, beta Andromeda, that we proceed about a quarter the way to the top star in the W of Cassiopeia, and look for a faint blur with the naked eye. M-31, the Andromeda Galaxy, is the most distant object visible with the naked eye, lying about 2.5 million light years distant. Overhead is Andromeda’s hero, Perseus, rises. Between him and Cassiopeia is the fine Double Cluster, faintly visible with the naked eye and two fine binocular objects in the same field. Perseus contains the famed eclipsing binary star Algol, where the Arabs imagined the eye of the gorgon Medusa would lie. It fades to a third its normal brightness for six out of every 70 hours, as a larger but cooler orange giant covers about 80% of the smaller but hotter and thus brighter companion as seen from Earth. At Perseus’ feet for the famed Pleiades cluster; they lie about 400 light years distant, and over 250 stars are members of this fine group. East of the seven sisters is the V of stars marking the face of Taurus the Bull, with bright orange Aldebaran as his eye. The V of stars is the Hyades cluster, older than the blue Pleaides, but about half their distance. Yellow Capella, a giant star the same temperature and color as our much smaller Sun, dominates the overhead sky. It is part of the pentagon on stars making up Auriga, the Charioteer (think Ben Hur). Several nice binocular Messier open clusters are found in the winter milky way here. East of Auriga, the twins, Castor and Pollux highlight the Gemini. UWF alumni can associate the pair with Jason and the Golden Fleece legend, for they were the first two Argonauts to sign up on his crew of adventurers.

South of Gemini, Orion is the most familiar winter constellation, dominating the eastern sky at dusk. The reddish supergiant Betelguese marks his eastern shoulder, while blue-white supergiant Rigel stands opposite on his west knee. Just south of the belt, hanging like a sword downward, is M-42, the Great Nebula of Orion, an outstanding binocular and telescopic stellar nursery. The bright diamond of four stars that light it up are the trapezium cluster, one of the finest sights in a telescope. In the east rise the hunter’s two faithful companions, Canis major and minor. Procyon is the bright star in the little dog, and rises minutes before Sirius, the brightest star in the sky. Sirius dominates the SE sky by 7 PM, and as it rises, the turbulent winter air causes it to sparkle with shafts of spectral fire. Beautiful as the twinkling appears to the naked eye, for astronomers this means the image is blurry; only in space can we truly see ‘clearly now’. At 8 light years distance, Sirius is the closest star we can easily see with the naked eye from West Florida.

When Sirius is highest, along our southern horizon look for the second brightest star, Canopus, getting just above the horizon and sparkling like an exquisite diamond as the turbulent winter air twists and turns this shaft of starlight, after a trip of about 200 years!

To the northeast, a reminder of Spring coming; look for the bowl of the Big Dipper to rise, with the top two stars, the pointers, giving you a line to find Polaris, the Pole Star. But if you take the pointers south, you are guided instead to the head of Leo the Lion rising in the east, looking much like the profile of the famed Sphinx. The bright star at the Lion’s heart is Regulus, the ‘regal star’, but brighter still is Saturn, well east in Leo’s hind leg and rising about 8 PM as February begins. On March 8th, we pass between Saturn and the Sun, so Saturn rises at opposition, coming up at sunset and staying up all night. As we are then closest to the ringed wonder, this is the best time to observe the most beautiful object in the sky. Now the rings are exquisitely thin, almost edge on, and it takes a good scope to spot them…may be easier to see the dark shadow of the ring cutting across the disk of Saturn, in fact.

Read past issues of the Sky at Night