February 2006

by Deane Morrison

Both Mars and Saturn pay visits to famous star clusters in February. In the east, Saturn skims the southern outskirts of the Beehive cluster early in the month. In the west, Mars glides a couple of degrees south of the Pleiades in mid-month. Between the two bright planets are the glorious winter stars, including Sirius, the brightest of all.

The only other evening planet is Mercury, which pops into the western sky around the 8th. On the 28th, sharp-eyed viewers may be able to use Mercury to spot a razor-thin crescent moon sitting just above the horizon to the lower left of the planet.

Early risers will find Jupiter well up in the south at dawn. But Jupiter's reign as the brightest celestial object is cut short when Venus rises and shines--brilliantly--about two hours before sunrise. Between the king and queen of planets are the Teapot of Sagittarius and the sinuous form of Scorpius with its red heart, the bright red star Antares.

Groundhog Day is a remnant of ancient Celtic rituals. It was called Imbolc, or lamb's milk, and was one of four cross-quarter days falling midway between a solstice and an equinox. The day was thought to be auspicious if it was cloudy, for clouds meant warmth and rain to loosen up soils for planting. Bright sun portended cold and low humidity, which led to our modern tradition that six more weeks of winter will follow if the groundhog sees its shadow.

Late February is a good time to look for the zodiacal light, a faint oval glow along the sun's path an hour or two after sunset. To see this ghostly light, you must have dark and moonless skies; this year, at least the moonless part is guaranteed for late February. This is also a favorable month to see the Gegenschein, or counterglow, at about midnight, high in the southern sky. Both phenomena are caused by reflection of sunlight on meteoric dust in the plane of the solar system.

The full moon of February, called the snow moon or the hunger moon by Algonquin Indians, rises on the 12th. It wanes away to a new moon on the 27th.

While you're out admiring the bright stars of winter, take a moment to consider one of the most familiar yet overlooked: Polaris, the North Star. For centuries this star has guided mariners, pointing the way north when there was no other way to tell direction. Recently, astronomers used the formidable power of the Hubble Space Telescope to spot a long-suspected companion to Polaris. While Polaris is a huge star approximately four times as big and more than 2,000 times as bright as the sun, its companion, called Polaris Ab, is close to the sun in size and brightness. Because the distance between Polaris and Polaris Ab is only about 2 billion miles -- the approximate distance between the planet Uranus and the sun -- it's no wonder the fainter star was so hard to find. Polaris also has a more distant companion, known as Polaris B, that was discovered by the astronomer William Herschel in 1780. Orbiting at a whopping 200 billion miles or so from Polaris, this star is considered a companion because it moves through space in the same manner as Polaris. If you have Web access, Hubble pictures and a story are available at http://spacenews.dancebeat.info/article.php/hubble-polaris-companion or http://www.msnbc.msn.com/id/10775641/.

Space has been in the news quite a bit recently. University of Minnesota physics professor Robert Pepin will be analyzing gases in comet dust that was collected in deep space by the Stardust spacecraft and returned safely to Earth in January after a six-year, 2.88-billion-mile journey through the solar system. Pepin is looking for clues to how our solar system formed and evolved, and the comet is considered a remnant of the embryonic solar system.

Planet Pluto has also been in the news. Astrophysicists have taken the temperature of the icy planet's surface: It's minus 382 degrees F, even colder than expected. Also, on Jan. 19 NASA's New Horizons spacecraft blasted off for Pluto on a trip that will take 10 years. Pluto was long thought to have just one moon, a large one called Charon. But in 2005, astronomers discovered two tiny moons in the Pluto-Charon system. Very little is known about this dark and mysterious world, but the names sure fit. Pluto is the Roman name for the Greek god Hades, the lord of the underworld. Charon was the ferryman who took souls across the Styx, the principal river of the underworld. Ten years is a long time to wait, but the New Horizons mission promises a fascinating look at this remote corner of the solar system.