Minnesota Starwatch is a newsletter describing the night sky in the Midwest.
Updated monthly, it is produced by the
Minnesota Starwatch for February 2017
by Deane Morrison
For a short month, February packs a lot of celestial delights.
In the southwest, Venus outshines everything but the moon. For months the brilliant planet has been moving closer to Mars, the dimmer object to its upper left, but in the first few days of February it changes course and begins to drop toward the sun's afterglow.
Venus also waxes brighter, reaching a peak on the 17th. On that day it will appear in telescopes as a crescent, only about a quarter lit. Venus's brightening and its motion in the sky both happen because it is swinging closer to Earth. It completes its fall into the sunset in March, when it zips between Earth and the sun.
In February the knot of bright winter constellations rides highest in the south during prime evening viewing hours. You might especially notice the two brightest stars in Orion (the hunter): Betelgeuse, in the northeast corner of the constellation; and Rigel, in the opposite corner. Both are gigantic stars that will end their days in a supernova explosion. And, of course, there is Sirius, just southeast of Orion in Canis Major, the larger of Orion's hunting dogs. Only about nine light-years away, Sirius is the brightest of stars and always a beautiful sight.
You may also want to take advantage of the opportunity to compare the brightest star and the brightest planet. Sirius is breathtaking when it has only other stars for company, but its radiance pales next to Venus's legendary luminosity.
February's full moon rises the evening of the 10th, becoming perfectly full at 6:33 p.m. On that evening the moon passes through the Earth's penumbra, or light outer shadow; the height of this subdued eclipse comes at 6:43 p.m. February's full moon was known to some Algonquin Indian tribes as the snow moon. And because the snow made hunting difficult, it was also known as the hunger moon.
For morning viewers, Jupiter is high and brilliant in the southwestern predawn sky, with the bright star Spica, in Virgo, below it. Saturn, in the southeast, shines to the left of reddish Antares, the heart of Scorpius.
Goundhog Day is an ancient Celtic holiday with astronomical roots. The Celts called the day Imbolc, or lamb's milk, and it was one of four cross-quarter days falling midway between a solstice and an equinox. The thinking long ago was that if the day was sunny, it predicted cold and continued winter. But heavy clouds, and therefore no shadows, meant warm spring rains were on their way to soften up the fields for planting. In today's rituals, if the groundhog sees its shadow it portends six more weeks of winter, whereas no shadow means spring is right around the corner.
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics (during fall and spring semesters): www.astro.umn.edu/outreach/pubnight
Check out the astronomy programs at the University of Minnesota's Bell Museum ExploraDome: www.bellmuseum.umn.edu/ForGroups/ExploraDome/index.htm
1/24/17 Contact: Deane Morrison, University Relations, (612) 624-2346,
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu.