Jimmy Westlake: Venus and Jupiter light up the night
March 5, 2012
Steamboat Springs — During the first two weeks of March our evening sky is swarming with bright planets — Mars in the east and Jupiter and Venus in the west. You might even catch a glimpse of the elusive Mercury. These planets are the first "stars" to pop out in the night sky because they are so bright, but unlike the fixed stars, the planets drift around relative to one another and the background stars. You can easily observe the planets in motion this month.
As March begins, Jupiter hovers 11 degrees above Venus in the western sky after sunset — that's about the width of your fist held out at arm's length — but that gap shrinks by nearly a degree each night until, on March 13, the two brightest planets in the sky will shine only 3 degrees apart. Wow! What a glorious sight. After that, the planets trade places, with Venus being the higher of the two, and the distance between them grows by nearly a degree each night. By month's end, Jupiter will be 15 degrees below Venus, and Venus will be closing in on the Pleiades, or "Seven Sisters," star cluster. Use your binoculars to see the Queen of the Night surrounded by glittering stars when she glides right through the Seven Sisters on the evening of April 3.
If you own a small telescope, you can rediscover what the famed Italian astronomer Galileo did way back in the year 1610 when he aimed his small telescope skyward. Aim your telescope at Venus and you can see that she shows off different phases, like our moon. Right now, Venus looks like a tiny half moon through a telescope, but this phase will change into a thin crescent in the coming weeks. After she reaches her greatest elongation on March 27, Venus will dive toward the sun and disappear from our evening sky in early June, but not before treating us earthlings to one of the rarest of celestial sights — a transit across the face of the sun.
Aim your telescope at Jupiter and you will spy its four giant moons — Io, Europa, Ganymede and Callisto. Every night, the moons take different positions around the bright ball of Jupiter as they zip around their orbits. One night, you might see all four on one side of Jupiter, then the next night, two on one side and two on the other. Sometimes, one or more moons might be out of sight, hiding in front of or behind their giant host. Watching the dance of Jupiter's moons is a delightful celestial pastime.
As March turns into April and April into May, Jupiter will fade away into the sunset and disappear from our evening sky altogether. On May 13, Jupiter will pass behind the sun only to reappear in our early morning sky this summer.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out Westlake's astrophotography website at http://www.jwestlake.com.