Comet and Earth to have rare close encounter
Typically during the course of a year about a dozen comets will come within the range of amateur telescopes. Most quietly come and go with little fanfare, but during the upcoming weeks one rather small comet will be making an unusually close approach to the Earth. On Oct. 20, Comet Hartley 2 will pass just over 11 million miles from Earth. During October it should be easily visible in small telescopes, binoculars and from sites with dark enough skies even with the naked eye. This video sky map shows how to spot the comet. Comets are composed of rock, dust, water ice and frozen gases such as carbon monoxide, carbon dioxide, methane and ammonia. [ Best Comet Appearances of All Time ] Because of their low mass, comet nuclei do not become spherical under their own gravity as larger bodies in space do, and thus have irregular shapes. They are often popularly described as "dirty snowballs," though recent observations have revealed dry dusty or rocky surfaces, suggesting that the ic