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Oort Cloud

The Oort Cloud is an immense cloud that surrounds our solar system. It was first proposed by the Dutch Astronomer Jan Oort in 1950. However the original idea was hypothesized by the Estonian Astronomer Ernst Opik in 1932.
The Oort cloud expands nearly three light years from the sun and is considered to be the edge of the sun’s gravitational influence. The cloud is made up of millions of icy bodies in a weak solar orbit. It is thought to be split into two regions, a spherical outer Oort cloud and a disk-like inner Oort Cloud. The outer orbit supplies long period comets and maybe Halley-like comets to the inner orbit of Neptune. These long period comets get their orbits changed as they pass stars and will streak towards the inner solar system. They have very large obits and usually seen only once. The inner Oort Cloud is also known as the Hills Cloud, named after J. G. Hills, who proposed its existence in 1981. It’s thought that the inner orbit contains tens or hundreds times as many cometary nuclei as the outer orbit. The outer Oort is thought to hold several trillion comet nuclei larger than 1.3km. Since these bodies are millions of kilometers apart it is hard to say the exact mass. However, using Halley’s Comet as a model it is estimated that the combined mass is 3x1025 kilograms, or around five times the mass of the Earth.
The comets in the Oort Cloud are mostly created from several types of ices. Some of these are water, methane, ethane, carbon monoxide and hydrogen cyanide. The discovery of the asteroid, 1996 Pw showed that the cloud was home to rocky objects as well. Samples from the Oort Cloud and Jupiter family comets were analyzed and showed that the carbon and nitrogen isotopes were very similar. This means that they both were made from the original proto-solar cloud.
The Oort cloud is believed to be remains of the original proto-planetary disc that formed around the Sun around 4.6...