1. Others migrated to the Oort Cloud, over a trillion miles from Earth.

2. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere.

3. The possibility that an invisible solar companion passing through the Oort cloud every 28 Myr precipitates a sufficiently high rate of Cometary collisions with the earth to account for periodic mass species extinctions recorded in the fossil record is discussed

4. By The Astronomist on Monday, November 18, 2013 There is a new object in the sky. Comet ISON is an icy wanderer making its first and probably last last trip into the solar system from its previous home in the Oort cloud