Washington: Stargazers can get a glimpse of a one-time-only visitor- Comet PanSTARRS - in the dark western sky this week.
But it will be visible only in the world's north mid-northern latitudes, from places like U.S., Canada, Europe except the north, China, Korea and Japan.
Skywatchers have been anticipating Comet PanSTARRS for almost two years. It's now passing closest by the Earth just as it's being lit most brilliantly by the Sun. In the past couple weeks it decorated the twilight sky for folks in the Southern Hemisphere.
Now people in the world's mid-northern latitudes have their turn. The comet should be at its best March 12-18, possibly just bright enough to spot with the unaided eye in clear twilight if you know exactly where to look.
"Our good views should begin around March 12th and 13th, when the crescent Moon is there to point the way," said Alan MacRobert, a senior editor at Sky and Telescope magazine.
"Before then the comet was too near the horizon. It will start fading later this week, so if the sky is clear, don't miss your chance," he noted.
By March 20th it should be only half as bright as it was seven days before, but on the other hand it will be a little higher and seen through thinner, clearer air.
The best time to look is about 30 to 45 minutes after your local sunset time. This narrow window of viewing time comes after twilight fades enough for the comet to show through at all, but before it sinks too low and sets.
On Tuesday March 12th, look for the very thin crescent Moon very low due west. The comet will be just to its left, by two or three finger-widths at arm's length. On Wednesday March 13th, you'll see a thicker crescent Moon higher up. Look below it by about the width of your fist at arm's length. On Thursday the 14th, look two fists below the Moon and perhaps a bit to the right. After that, the comet will gradually move to the right from evening to evening as it begins to fade.
Those interested can use binoculars to get the best view, said scientists.
First Published: Wednesday, March 13, 2013, 11:18