The Oort comet cloud

The Oort comet cloud

Fig. 14.8 . More than 200 billion comets hibernate in the remote Oort comet cloud, shown here in cross section. It is located in the outer fringes of the solar system, at distances of about 100,000 AU from the Sun. By comparison, the distance to the nearest star, Proxima Centauri, is 0.27 million AU, while Neptune orbits the Sun at a mere 30 AU. The planetary realm therefore appears as an insignificant dot when compared to the comet cloud, and has to be magnified by a factor of 1,000 in order to be seen. This comet reservoir is named after the Dutch astronomer Jan H. Oort (1900-1992) who first postulated its existence in 1950.

Copyright 2010, Professor Kenneth R. Lang, Tufts University