Representation of the Oort Cloud in relation to the Solar System |
What is the Oort Cloud?
In an effort to explain the
behavior of long term comets, Jan Oort hypothesized the existence of a cloud
like region of space past the planets and the Kuiper Belt at the outer edges of
our solar system. The Oort Cloud, as it came to be known, is believed to have
originated from the protoplanetary disc at the same time the solar system was
developing.
The cloud has two regions. The
inner region, called the Hills Cloud, is strongly bound to the Sun so it
maintains a disc shape. This region begins two thousand to five thousand AU
from the sun and extends to twenty thousand AU. The outer region has a spherical
shape due to gravitational interaction with nearby stars. It lies from twenty thousand AU to as much as two hundred thousand AU. It could possibly
contain trillions of objects larger than one kilometer. Scientists
have used Haley’s Comet as a typical representation of Oort material and
calculated that the outer cloud has a mass of five Earths.
Both regions contain what scientists call
Trans Neptunian Objects- comets and other icy materials. Based on research of
past comets, it is believed to be comprised mostly icy volatiles such as water,
methane, ethane, carbon monoxide, hydrogen cyanide, and ammonia. Research
suggests that it also consists of one to two percent asteroids.
Source:
Williams, Matt. "What is the Oort Cloud".Universe Today. 2015. Web. 30 Nov 2015