By Peter Becker
Interest is high in a potentially bright comet that may grace our evening night sky during the first half of March. Astronomers are necessarily cautious to make predictions, given many variables that could affect just how bright or large it will appear.
Known as Comet PanSTARRS, the comet will be making its first passage around the Sun, re-emerging from the Sun's glare in early March. Look low in the western sky during twilight; binoculars will enhance your view.
Currently the comet is visible only from the Southern Hemisphere, at magnitude +8, needing binoculars or a small telescope to see its glow. Comets brighten as they near the Sun, and sport a growing tail of material, thrust back by the push of particles from the Sun, the Solar Wind.
Comets vary greatly. The public perception is of a grand, brilliant comet, and unfortunately one that quickly darts across the sky as you watch it. Meteors shoot across the sky. Comets seem to "just sit there" like the stars and planets, when seen at a passing glance with out a telescope.
As you watch carefully in a telescope, you can witness the movement of a comet in front of the background stars. They are actually moving at great speed, but are also very far away.
Almost all comets remain very dim and need a telescope to see them. A very few become so bright and wonderful, that the public at large takes notice. The last two very large comets easily visible from the Northern Hemisphere were Comet Hyakutake in 1996 and Comet Hale-Bopp in 1998. We are long over due!
Comet PanSTARRS is closest to the Sun- which is known as "perihelion"- on March 10. Solar heating the most intense, causing the cometary ice to vaporize and trapped dust to be released. The comet itself is referred to as the nucleus; what you will see best is the cloud of dust and gas around it, known as the coma. The tail on the rare, great comets, attract the most public attention.
Even if the comet is a lot less bright than originally expected, amateur astronomers anticipate it will be a fine sight in their binoculars and backyard telescopes.
On March 12, the thin crescent Moon will appear just to the right of the comet, low in the bright dusk.
The comet was discovered in June 2011 using the PanSTARRS telescope in Hawaii.
Last quarter Moon is on February 3rd.
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Keep looking up!