Jimmy Westlake: A new Comet Lovejoy for the new year
January 5, 2015
It has been one year since Comet Lovejoy 2013 R1 glided across our winter sky and upstaged a much overrated and underperforming Comet ISON. Now, Australian comet-hunter Terry Lovejoy's newest discovery, Comet Lovejoy 2014 Q2, is delighting sky gazers in the Northern Hemisphere with its popsicle green head that is visible to the unaided eye in clear, dark skies.
Comets are like big, dirty snowballs, more than anything else, which hover near the outer edges of the solar system in perpetual cold and dark. If a comet gets nudged into an orbit that takes it into the warm inner solar system, its icy material sublimates into a vapor cloud that engulfs the snowball and puffs up into a glowing head, called the coma.
Solar radiation acting on diatomic carbon molecules in the coma causes them to glow with a striking green color. Carbon monoxide molecules are forced to glow with an icy blue color. The pressure of the solar wind blowing past the comet can carry away these gases and form a wavy, twisted ion tail that always points away from the sun.
Comets are named for the person, persons, or robotic telescope that discovers them. Terry Lovejoy has now discovered five comets, each bearing his name. He uses a rather small 8-inch backyard telescope (with lots of fancy bells and whistles, to be sure) to patrol the southern skies for the telltale fuzzy wisps of incoming comets.
His most recent comet discovery – Comet 2014 Q2 – was made last August while it was still very far from Earth and sun. Now, Comet Lovejoy Q2 is here, and it is outperforming its original brightness predictions.
Comet Lovejoy Q2 is an icy visitor from the distant Oort Cloud of comets that surrounds our solar system, but this is not its first pass through the inner solar system. According to the website http://www.SkyandTelescope.com, it's been about 11,500 years since this Comet Lovejoy last passed through the inner solar system. Gravitational tugs on the comet by the much larger planets during the current visit have shortened its orbital period to about 8,000 years, so we won't have to wait so long for its next return.
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The full Wolf Moon on Jan. 4 hindered comet viewing for a few nights, but starting about Jan. 7, there will be a dark window after sunset before the moon comes up. It is during these moonless middle two weeks of January that Comet Lovejoy Q2 will be at its best and even visible, faintly, to the unaided eye.
It will probably look like a small, fuzzy, green dandelion head to the unaided eye, with maybe a slight hint of a tail pointing eastward. Look for it about one hand span west of the bright star Rigel, marking Orion's foot Jan. 7.
By Jan. 17, it will have moved northward and will be positioned about one fist width west of the little Pleiades star cluster in Taurus. The moon will enter the scene again after Jan. 22 and begin to interfere with viewing the faint comet. By the time February's full Snow Moon gets out of the way, the comet will have faded considerably.
Comet Lovejoy Q2 will be closest to Earth on the night of Jan. 7 at a distance of 0.47 astronomical units (about 44 million miles) and closest to the sun Jan. 30. Based on its current rate of brightening, Comet Lovejoy Q2 is expected to peak in mid-January around magnitude 4.0. Binoculars will definitely enhance the view and show more of the comet than your eyes alone can see.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. Check out Westlake's new "2015 Cosmic Calendar" of sky events on his website at http://www.jwestlake.com. It features 12 of his best astrophotographs and a day-by day listing of cool celestial events that you and your family can enjoy watching in 2015.