Jimmy Westlake: Bidding farewell to Comet PanSTARRS
March 25, 2013
Comet PanSTARRS, the first of two bright comets expected this year, already has reached its peak brightness and is fading as it heads back to the outer solar system. Paradoxically, your chances of spotting the comet are actually improving this week.
Comet PanSTARRS is named for the automated telescope atop the Haleakala volcano on the island of Maui that discovered it in June 2011: the Panoramic Survey Telescope and Rapid Response System, or PanSTARRS. Its early discovery while still beyond the orbit of Jupiter created great excitement about the prospects of a bright comet visible from Earth. Comet PanSTARRS made its closest approach to and sharp turn around the sun on March 10, just inside the orbit of the sizzling planet Mercury. Before March 10, PanSTARRS was a southern hemisphere spectacle, but since then it has moved into view for northern hemisphere observers.
Nearly perpetual evening clouds since March 10 have kept Comet PanSTARRS mostly hidden from our view here in Northwest Colorado. Patient skywatchers might have captured a glimpse between the clouds or on the rare clear night. But while the comet has been moving out of the sunset glow and into darker skies, the moon has been moving toward its full phase and brightening the night sky. The full Egg Moon occurs on March 27, effectively drowning out the faint extensions of the comet's tail.
All that changes beginning March 28, when the comet sets before the moon rises at around 9:30 p.m. If the skies clear, the last few days of March and the first few days of April will provide the best views of Comet PanSTARRS in a dark sky before it fades away into the distance.
A night of particular interest is April 4, when Comet PanSTARRS will appear just 2.5 degrees from the famous Andromeda Galaxy. Also known by its catalogue number M31, Andromeda is the closest large galaxy to our own Milky Way, at the staggering distance of 2 million light years. Like the comet, M31 is visible to the unaided eye on a clear, dark night as a faint, fuzzy wisp. The two fuzzy wisps should appear very similar in brightness and size and will offer quite a "cosmic moment" when viewed together through binoculars. Look low in the northwestern sky just below the familiar W-shaped star pattern of Cassiopeia, around 8:45 p.m. for the best view.
The comet will remain visible through binoculars and telescopes throughout April, fading a little each day as it recedes from the sun and Earth. This frozen visitor from deep space won't return to our neck of the woods for more than 100,000 years. Farewell, Comet PanSTARRS.
On deck: Comet ISON, coming Thanksgiving 2013!
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out Jimmy's astrophotography website.