If you still want to see Halley's Comet as it moves toward the sun, the next two weeks offer some of the best views people in northern latitudes will have of the comet's 30th recorded visit to our neighborhood.
From now until the middle of January, the comet will be about 30 degrees above the horizon in the southwestern sky two hours after sunset. Even though the comet is still 90.4 million miles from the sun, it has begun to form a tail as the sun's heat begins to boil off the ices that cover the Manhattan-sized object that has been returning to Earth every 76 years since 240 B.C.
"The comet now has a tail that's 16 million miles long," said Raymond Newburn, a director of the International Halley Watch at California's Jet Propulsion Laboratory. "The trouble is, it doesn't look that long to us because the geometry is wrong and the comet's now about 111 million miles from Earth."
Not only does Halley have a tail, it also has begun to brighten as the sun boils an estimated 1 million tons of water off the comet every day. By the time the comet circles the sun in February and begins its outward bound journey to the deep freeze of space between Neptune and Pluto, the comet will have lost more than three feet of the ice that makes up its outermost skin.
"Every time this comet comes around the sun, it loses about one meter of surface," said Donald K. Yeomans, the other director of the Halley Watch at JPL. "Since we think the comet is at least three kilometers two miles in radius, that suggests Halley will be around as a very bright comet for a long time to come."
If you travel in the next two weeks into dark skies away from city lights, look to the southwest to the right of the constellation Aquarius and look below the four stars that make up the constellation's "Water Jar," the fuzzy ball of cotton you see just below the water jar is Halley's Comet.
If you still can't find it, says Sky and Telescope magazine, look low in the sky where there will be a bright yellow-tinted star that is really the planet Jupiter. Next, look for a dim star above and to the right of Jupiter about as far from the planet as the width of your fist at arm's length.
That's the star Beta Aquarii, which was known to the ancient Arabs as Sadalsuud, "the luckiest of the lucky." Above it is the star Alpha Aquarii. Halley's Comet is to the left, by the width of two fingers at arm's length.
Halley will stay in Aquarius for most of January but by the end of the month will be so close to the sun that its glare will wash out any chance we have of seeing the comet until the end of February. The comet reaches perihelion or closest approach to the sun on Feb. 9 when it flies behind the sun at a distance of 54.7 million miles from the sun's surface.