What is the difference between the Kuiper Cloud and the Oort Cloud?
The Kuiper Cloud, or more correctly the Kuiper Belt (roughly the dotted region in the above cartoon), is a disk shaped population of comet nuclei 'in waiting' beyond the orbit of Saturn. The Hubble Space Telescope, and ground-based observers, have detected dozens of these nuclei, each more than 50 kilometers across.
There are believed to be thousands of these proto-comets stretching all the way out past the orbit of Pluto. Eventually, we believe they merge together with the Oort Cloud, which contains trillions of cometary bodies in a roughly spherical cloud up to several light years across. The Oort Cloud is all that remains of the primordial cloud which gave rise to the Sun and the solar system. It has not been detected yet.
For a current count and spectacular plot of the known Trans-Neptunian Bodies, visit the Minor Planets Center. for an up-to-date display which I reproduce below ca May 2000.
Their caption reads:
The plot below shows the orbits of the Jovian planets and the current locations of various distant minor
planets. The orbits of the planets are shown in light blue and the current location of each object is
marked by large dark-blue symbols. The current location of the minor bodies of the outer solar system
are shown in different colors to denote different classes of object. Unusual high-e objects are shown as
cyan triangles, Centaur objects as orange triangles, Plutinos (objects in 2:3 resonance with Neptune) as
white circles Pluto itself is the large white symbol), scattered-disk objects as magenta circles and
"classical" or "main-belt" objects as red circles. Objects observed at only one opposition are denoted
by open symbols, objects with multiple-opposition orbits are denoted by filled symbols. Numbered
periodic comets are shown as filled light-blue squares. Other comets are shown as outline light-blue
squares. Dual-status objects are shown as minor planets.
Copyright 1997 Dr. Sten Odenwald
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