The Night Sky of February
Dr. Wayne Wooten
Professor of Astronomy
For February 2012, the Moon will be full on February 7th; this is the "hunger" moon in Native American tradition, when most of the food store up for winter was almost gone. The first week finds the moon waxing in the evening sky, then waning in the morning sky for the middle weeks of this month. The waning gibbous moon lies nine
degrees south of Mars in the morning sky on February 10th. The moon then passes six degrees south of Saturn in morning sky on February 12th. Last quarter moon sits high in the sky and half-lit at sunrise on February 14th. The new moon is on February 21st. The waxing crescent moon passes 3 degrees north of Venus on February 25th, then passes 4 degrees north of
Jupiter on February 27th.
Venus dominates the evening sky, so bright she can be seen in daylight if you know where to look. She sets about 8:30 PM on February 1, with a disk 15" across and 74% sunlight. By Leap Day at monthís end, she is is closer to us, with a disk 18" across, but only 63% sunlit and sets about 9:10 PM. Through the telescope, Venus now
appears as a small, round disk, on the far side of the Sun. She will appear larger as she approaches Earth and overtakes us, but her phase will become less sunlit as well.
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. She will in fact pass directly between us and the Sun on the
afternoon of June 5, 2012, a transit which will be visible with the naked eye with properly shielded solar viewer, from about 5 PM CDT until sunset about 7:30 PM that evening. This rare transit will not recur for another century, so hope for a clear afternoon then to see this event.
Mars is currently in the late evening sky, but will be coming to opposition and rise at sunset on March 2nd. As the earth overtakes Mars this month, the planetís size increases from 12" on February 1st to 14" on February 29th, and it rises in southeastern Leo at 8:30 PM on the 1st, but retrogrades westward and rises by 6 PM at
monthís end. As Mars lies on the far side of its elliptical orbit now, the Red Planet only gets up to magnitude -1.2 this opposition, so it will be far more distant, smaller, and fainter than during its famed close approach to earth in August 2003. Still, its red color will catch a lot of attention from stargazers looking in the east after sunset this month.
Jupiter starts the month 40 degrees above Venus in the SW at monthís start, but rapidly moving Venus overtakes the second brightest planet on March 13th; by the end of February, Venus lies only 12 degrees below Jupiter. Jupiter will be vanishing into the sunís glare by the end of March, so enjoy the four moons and its belts and zones
through the telescope now.
Saturn is now in Virgo near the bright star Spica, and rising about 10 PM by monthís end. The ringed planet will be coming to opposition on April 15th. The rings are gradually starting to open up again, but still rather thin, only tilted about 10 degrees now, compared to 27 degree when fully opened at Saturnís solstice in 2016;
when this open, the huge reflecting surface of the ringís ice boulders will double the planetís brightness.
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 Pegasusíí 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 Andromedaís 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 Perseusí 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. The pair is associated 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. Around the bottom star, Mintaka, of Orionís famed belt is the very faint (needs at least a 10" telescope!) but photogenic Horsehead Nebula (our photo this month), with the larger and brighter
Flame nebula to the left, closer to the belt star Mintaka.
In the east rise the hunterís 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 Lionís heart is Regulus, the "regal star". Fitting for our cosmic king of beasts, whose rising at the end of this month means March indeed will be coming in like a Lion. Mars is below the eastern "feet" of the Lion, but retrogrades westward toward the Lionís front feet during February.
Read past issues of the Sky at Night