Jimmy Westlake: Comet LONEOS
October 7, 2007
Steamboat Springs — Last March during an automated patrol of the night sky, the Lowell Observatory Near Earth Object Search, or LONEOS, discovered a tiny little blip on a photograph that was, at first, thought to be a new asteroid. Subsequent observations convinced astronomers that it was not an asteroid at all but a new comet, visiting the inner solar system for, perhaps, the first time. This new comet, called Comet LONEOS 2007F1, is back in the news this week because it is running about six times brighter than expected at this point in its orbit. If this trend continues, Comet LONEOS might become visible to the unaided eye during mid- and late-October. If it does, it will be the first naked eye comet visible from Northwest Colorado since Comet McNaught in January.
Comets are like big, dirty snowballs, more than anything else, that hover near the outer edges of our solar system in perpetual cold and dark. But, every so often, one of these snowballs will be nudged into an orbit that brings it into the warm inner reaches of the solar system, and this is when the excitement begins. Warmed by the sun’s radiant energy, the ices in the comet begin to boil away, releasing gaseous vapors and millions of tiny little dust grains. The pressure of sunlight and the solar wind blows the vapors and dust particles away from the snowball, creating the long flowing tails for which comets are famous. The word comet comes from the Greek word kometes, meaning “hairy star.” Indeed, many comet tails resemble long, flowing hair.
Will Comet LONEOS grow a tail that will be visible to the naked eye? It’s still a little too early to tell, but it might. Right now, Comet LONEOS is visible in binoculars just after sunset and just before dawn in the constellation of Coma Berenices, under the handle of the Big Dipper. An excellent opportunity to spot the comet with binoculars comes on the evenings of Oct. 19 and 20 when it will shine just 3 degrees below the bright orange star Arcturus, about a hand span high in the western sky at about 7 p.m. Comet LONEOS should appear brightest in our evening sky about Oct. 28 when it is at its closest point to the sun and boiling away most rapidly. You must catch it early in the evening, though, because it will set at about 7:45 p.m.
I’ll keep you posted on Comet LONEOS as we learn more about it.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the websites of CNN.com, NASA’s “Astronomy Picture of the Day” website, Spaceweather.com, Space.com, Discover.com, MSNBC.com, NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His “Celestial News” article appears weekly in the Steamboat Pilot newspaper. His “Cosmic Moment” radio spots can be heard on local radio station KFMU.