Where do comets come from?
Comets come from two major areas of our solar system: the Kuiper (pronounced KY-per) Belt and the Oort (pronounced OR-t) Cloud. Each of these regions contains billions of comets, but they have so much room in these vast rooms of space that they get no closer to each other than we on Earth do to the sun.
Comets are balls of ice and other material that can be ‘left overs’ from the formation of a solar system (ours or others). A solar system forms when a swirling cloud of gas and dust condenses enough to start an ongoing nuclear reaction in the middle of it – that’s the star. The rest of the gases and dust ‘accrete’ (gather together via gravitational forces) to eventually form planets. Not all of this material ends up in the planets and their moons. It is this material that can wind up in a comet.
There are two types of comets short-period and long-period comets. Short-period comets come from a KUIPER BELT ( a material belt ), which is in fact beyond Pluto. On the other hand, long-period comets come from the ORT CLOUD (a circle of rocks at the edges of the solar system). What does a comet consist of? There are five main parts to the comet. The first being the NUCLEUS, is made up of solid ice, small dust and gas. The COMA, another main feature of the comet, is a cloud made up of water and Carbon Monoxide which surrounds the nucleus. There is also the HYDROGEN CLOUD, which is an enormous cloud surrounding the comet which ranges in millions of kilometers in diameter. The DUST TAIL, is a trail leading from the comet that can be as long as ten million kilometers long which consists of dust the particles/debris from the comet. Lastly, the ION TAIL, which is a tail leading from the comet where the size is approximately a hundred million kilometers long. click on image to enlarge-Diagra
Mathematical theory suggests that most comets may come to the solar system from very far away, as far away as 100,000 AU. In this picture, the solar system is buried deep within the cloud. An AU is the distance from the earth to the sun and is equivalent to about 100,000,000 miles. Mars is 1.5 AU from the sun, Jupiter is 5 AU from the sun, and Pluto is 39 AU from the sun. So comets come from very far away indeed. Comets are observed to come to the solar system from all directions, therefore the place where the comets come from is thought to be a giant sphere surrounding the solar system. This sphere is called the Oort cloud after Jan Oort who suggested its existence in 1950. Thus comets are said to come from the Oort cloud.
Comets are found in two main regions of the solar system: the Kuiper Belt and the Oort Cloud. There are two types of comets: short-period comets and long-period comets. Short period comets – comets that frequently return to the solar system – probably come from the Kuiper Belt beyond the orbit of Neptune. Astronomers estimate that this belt contains at least 200 million objects, which are thought to have remained essentially unchanged since the birth of the solar system 4.5 billion years ago. Long-period comets, which can take thousands of years to complete their orbits, are thought to emanate from the Oort Cloud, a vast group of frozen bodies that surrounds the solar system. The Oort Cloud is thought to extend 50,000 times the distance from the Earth to the Sun. Oort Cloud comets, like their Kuiper Belt brothers, probably originated in the region of the solar system between Jupiter and Neptune, but were ejected from to the Oort Cloud by close encounters with the gravity of the giant p