You can never be sure about weather forecasts. But stargazers looking for Comet Lulin in the coming days will be encouraged by the predictions coming from NWS Sterling this morning. The forecast calls for mostly clear skies tonight, and again early next week - prime time for Lulin hunters.
As you may already have read, Lulin - a lovely green comet discovered in 2007 by astronomers in Taiwan and mainland China - has made its turn around the sun this winter and is now speeding off into deep space. That's Lulin in Gregg Ruppel's Feb. 6 photo above, just above the bright star Zubenelgenubi in Libra. (Ya gatta love a star named Zubenelgenubi! Sounds like Obi wan Kenobi.)
Lulin, like so many comets, is a visitor from the Oort Cloud, a realm of icy objects far beyond the orbits of the outermost planets. Something - perhaps a collision - sent or hurtling inward toward the sun. In January, the sun's gravity grabbed it and hurled back out toward the Oort Cloud, and it is only now passing our general vicinity, outbound.
Astronomers who have calculated Lulin's trajectory say it is parabolic, rather than elliptical, which suggests that it has never visited the inner solar system before. And that, they say, may explain why the comet's icy nucleus is spewing such large volumes of gas and dust. Solar heating and the stream of solar particles called the "solar winds" have been activating the comet's ices and dust and sending them off into space in the form of a large halo, or "coma" around the nucleus, and several "tails" of gas and dust.
Astronomers have been watching Lulin for months through their telescopes. Here is a beautiful gallery of their photos. And in recent weeks, as Lulin has drawn closer to Earth, it has been brightening to naked-eye visibility - at least from locations far from urban light pollution. But binoculars will be your best bet for finding the comet wherever you are.
Remember that it is moving each night as it hurtles back toward deep space. So it will be rising about a half-hour earlier each evening, and drifting westward with respect to the background stars. Baltimore's Streetcorner astronomer, Herman Heyn, has calculated Lulin's rise times for the next week, starting at 8:30 p.m. tonight. So, as the next week rolls by, the best viewing times will be getting a bit earlier each evening as Lulin rises higher in the evening sky.
Monday night may be the best opportunity to find Lulin. At around 11 p.m. that evening, Lulin will be just below Saturn in the southeastern sky. On prior nights look for it farther east; on subsequent nights, look farther west.
The star chart below is set for 11 p.m. Monday in Baltimore. On that night, Lulin will be right below Saturn. You should find it within the same binocular field of view as Saturn itself. Today's article in the print edition of The Sun includes a list of observatories opening for a Lulin watch, and a sky map.
As always, if you spot Lulin, drop back here and help the rest of us by describing what you saw, where you were, how dark your skies were, the time of night, and how hard (or easy) it was to find. Good hunting!