A comet lights up

A comet lights up

. When a comet travels close to the Sun, the solar heat vaporizes ice from the comet's surface, and solar forces bend the liberated material into comet tails that always point away from the Sun. The long tail of this comet stretches 120 billion (1.2 x 1011) meters, or nearly the mean distance between the Earth and the Sun, at 1 AU = 1.496 x 1011 meters. It is named Comet Ikeya-Seki (1965 VIII) after the last names of its discoverers, Kaoru Ikeya and Tsutomu Seki, and the year and order of its discovery. ( Courtesy of the Lick Observatory.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University