An artist's concept of the Oort cloud. Credit: NASA

Far beyond the orbits of Neptune and Pluto, where the sun is a pinprick of light not much brighter than other stars, a vast swarm of icy bodies circles the solar system. Astronomers call it the "Oort Cloud," and it is the source of some of history's finest comets.

Comet Pan-STARRS was discovered by the Panoramic Survey Telescope & Rapid Response System atop the Haleakala volcano in Hawaii. Astronomers use the massive 1.8 meter telescope to scan the heavens for Earth-approaching objects, both asteroids and comets, that might pose a danger to our planet. In June 2011 a comet appeared, and it was named "Pan-STARRS" after the acronym for the telescope.

In early March, the comet will pass about 100 million miles from Earth as it briefly dips inside the orbit of Mercury. Most experts expect it to become a naked-eye object about as bright as the stars of the Big Dipper.

"But" says Karl Battams of the Naval Research Lab, "prepare to be surprised. A new comet from the Oort Cloud is always an unknown quantity equally capable of spectacular displays or dismal failures."

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