Comet Double Feature: Comets Elenin & Garradd Now Showing in Night Sky
Skywatchers often ask “When’s the next comet?” In fact, if you’re prepared to do a bit of searching, there are always several comets visible in the night sky, including two right now.
Some comets are like old friends, they keep coming back at regular intervals to visit. These are called periodic comets; Comet Halley was the first such comet to be identified, by Edmond Halley back in 1705. It returns to the inner solar system every 75 to 76 years; its last appearance was in 1986 and its next will be in 2061. At present Halley is out just beyond Neptune;s orbit.
Other comets are one-time visitors: they come in to visit us from the Oort Cloud, warm themselves for a few months by the sun, and then head back out to the farthest reaches of the solar system.
to read more, go to: http://www.space.com/12746-comet-elenin-comet-garradd-night-sky-observing-tips.html