The Night Sky of February

Dr. Wayne Wooten
Professor of Astronomy

For February 2011, the Moon will be new on February 3rd. The first two weeks find the moon waxing in the evening sky. The slender crescent moon lies six degrees north of Jupiter in the evening twilight on February 7th. First quarter moon sits high in the sky and half-lit at sunset on February 11th. The full moon is on February 18th and in folklore, is the Wolf or Hunger Moon. The waning gibbous moon passes seven degrees south of Saturn on February 21st, with both rising about 10 PM. The Moon is last quarter on February 24, so the last two weeks of this month will find the moon in the morning sky, making evenings dark for deep sky observations.

Venus dominates the dawn sky. She rises about 4 AM all month, but is heading behind the Sun in the next few months. She is 61% sunlit with a disk 20" across on February 1st, but 71% sunlit and now farther away from us, appears only 16" across by the end of the month. 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 when she moves into the evening sky later this year. 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.

Mars is currently behind the Sun and lost in his glare, as is true of Mercury as well. Even Jupiter is soon disappearing in the south western sky by month’s end. Saturn is now in Virgo near the bright star Spica. The ringed planet will be coming to opposition on April 3rd. 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 Saturn’s solstice in 2016; when this open, the huge reflecting surface of the ring’s ice boulders will double the planet’s 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 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.

To the east of Betelguese is the cluster NGC 2244, visible in binoculars. But appropriately for Valentine’s day at midmonth, surrounding this cluster is the beautiful Rosette Nebula, featured in our photo this month. Older than the Orion’s M-42 cluster, here the hot central stars have driven away the gas and dust, which has accumulated on the edges in this fine bloom in the February skies for deep sky observers and astrophotographers.

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". 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.

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