Where comets come from?

In addition to the periodic comet, and constantly open or closed orbit comet visits the inner solar system. New comets come from? This issue will be talked about from the formation of the solar system.
The origin of the solar system:
The predecessor of the solar system, a gas cloud of gas and dust, the cloud may be 4.6 billion years ago, a supernova explosion shock wave compression, start slowly rotating trap shrunk discoid, the center of the disc is young sun. The disk of gas clouds particles collide with each other, there is a considerable ratio of material condensed into planets and their satellites, and another part of the remnants of clouds substances condense into a comet.

When the solar system was young, the comet may be seen everywhere, these comets are often associated with the beginning of the formation of the planets collided with a far-reaching impact on the growth and evolution of young planets. A large amount of water on Earth, may be the heritage of many comets collided with the young Earth, the water and later gave birth to a wide range of life in the Earth.

More than four billion years after the formation of the solar system, comets near the area of ​​the center of the solar system, or collide with the sun, planets and moons, or by evaporation of the solar radiation, has disappeared till the best, we are now seeing the comet from the edge of the solar system . Assuming residual comet material in the outer solar system, after billions of years has not changed, the study of these comets, help to understand the original chemical composition and state of the solar system.


The comet's hometown:
The theory is now widely accepted by astronomers, the big family of the solar system, including the nine planets and the outer Kuiper Belt and the Oort cloud. The long-period comets may come from the Oort cloud and short-period comets from the Kuiper belt.

Oort cloud theory:
In 1950, Dutch astronomer Jan Oort fullerene zone between 30,000 AU A light from the sun, hundreds of trillions of comets exist, these comets residues in the formation of the solar system. Some Oort comet occasionally by passing stars or collisions between each other, apart from the original track. Most-orbiting comet, never entered the large telescopes can detect the distance. Only a small number of comets into the inner solar system, with a wide range of orbital. But so far the the theoretical Oort cloud is only assumed that there is no direct observational evidence.



Kuiper Belt:
Oort cloud theory can be a reasonable interpretation of the arbitrariness of the angle between the source of long-period comets and comet with yellow pavement. Short of the comet's orbit in the orbital plane of the planets in our solar system, the Oort cloud theory can not reasonably answer the origin of short-period comets.

In 1951, the American astronomer Gerard Kuiper proposed a Kuiper Belt between 30 to 100 AU from the Sun (or called the Kuyper belt), to bring many of ice orbiting the sun, these ice orbital plane of the planets similar Occasionally, some of the Kuiper Belt objects by the gravity of the outer planets disturbance and traction, while running to the direction of the sun, crossed the orbit of Neptune, and further influenced by Neptune's gravity, and become short-period comets into the inner solar system.

Astronomer David Jewitt and Jane Luu since 1988, can detect very dim objects, high-sensitivity electronic cameras to find Kuiper Belt objects. They found in 1992, the first such objects (1992 QB1), 1992 QB1 291 years away from the average distance of the sun's 43AU, revolution cycle. Often referred to as Kuiper Belt objects beyond Neptune celestial the (List the Of Transneptunian Objects). 1992-2002, and one after another they found over 600 Kuiper Belt objects (the latest list can be found in the MPC's List Of Transneptunian Objects). At this stage, the astronomers think Pluto, Charon and Triton may have been into the inner solar system's Kuiper Belt Objects, and recently discovered the the melon Alvareaux (Quaoar), its size is about half of the Pluto.