Rare naked-eye comet now visible
Viewers in US may be able to see it with the naked eye
A rare treat for sky watchers is hovering overhead.
Comet Pan-STARRS is now visible on the western horizon in the Northern Hemisphere and viewers in the United States may be able to see it with the naked eye.
The comet has been visible through telescopes in the Southern Hemisphere for a while and amateur photographers are now posting sightings online from the Northern Hemisphere.
Scientists estimate that naked-eye comets happen only once every five to 10 years, according to the Jet Propulsion Laboratory.
If you have a clear view of the western horizon about 15 minutes after twilight, you should be able to see the comet without using binoculars or a telescope. It will look like a bright point of light with its tail pointing nearly straight up from the horizon, according to the laboratory.
In a few days, the comet may get lost in the sun's glare, but should be visible to the naked eye again by March 12. This may be the best time to look for Pan-STARRS; it should emerge in the western sunset sky not far from the crescent moon.
The comet will slowly fade from view and be hard to see by the end of the month, even using binoculars or small telescopes.
PanSTARRS gets its funky name from the telescope credited with discovering it: the Panoramic Survey Telescope & Rapid Response System in Hawaii.
Some comet viewing tips:
1) Safety first: Don't try to look at the comet until the sun sets. Do not look at the sun using regular binoculars or telescopes. Ever! You'll burn up your eyes.
2) Comet Pan-STARRS will stay close to the horizon, so you'll need to get away from trees and buildings.
3) Look carefully! The sky will still be bright at dusk, which can make it hard to spot comets.
4) If the skies are clear, and you are away from city light pollution, you may be able to see the comet with your bare eyes. If not, use binoculars.
5) If you can't escape the city, try using binoculars.
If you miss Pan-STARRS, we might get to see a better comet later in 2013: Comet ISON.
ISON was discovered by Russian astronomers Vitali Nevski and Artyom Novichonok in September 2012. It is named after their night-sky survey program, the International Scientific Optical Network.
On November 28, it is expected to dive into the sun's atmosphere. If it survives, it might glow as brightly as the moon and be briefly visible in daylight. Its tail might stretch far across the night sky. Or it could fall apart.
Scientists say they won't know until late summer what to expect from ISON.