Definition: Oort Cloud: A theory, now widely accepted, that the Sun is surrounded by a distant cloud of comet-stuff, now called the Oort Cloud, bits of which are occasionally hurled into the solar system as comets.
From Nick Greene, former About.com Guide
The top 10 fossil discoveries between 2000 and 2010. More >
Being well prepared is the first step; here are more essential suggestions. More >
©2010 About.com, a part of The New York Times Company.
All rights reserved.