Most of the comets that enter the solar system originate in either the Oort Cloud or the Kuiper Belt, zones containing trillions of icy and rocky bodies orbiting in the furthest reaches of the sun's influence. Gravitational perturbations or collisions occasionally cause these comets to approach Earth.
The Oort Cloud is a large spherical cloud surrounding the solar system, and it is the source of most long-period comets that take more than 200 years to make a full orbit. The Kuiper Belt is a disc-shaped area of space beyond Neptune where most short-period comets originate. Both zones are believed to be remnants from the creation of the solar system around 4.6 billion years ago.Learn More
Comets that appear in the inner solar system have generally been pulled by the sun's gravity from one of two large clouds in the outer solar system. The cometary nuclei in these formations, the Kuiper belt and the Oort cloud, formed around the same time in the early solar system. Since that time, around 4.6 billion years ago, the Kuiper belt has changed very little.Full Answer >
Space is filled with the tiny remnants of asteroids and comets. Often, these rocky bodies collide with other rocky objects, causing them to break apart. However, they can also fall apart as they are pulled in different directions by tidal forces. This occurs when the rocks fly close to a large object that has a significant gravitational pull.Full Answer >
The U.S. National Aeronautics and Space Administration describes comets as consisting of a nucleus, coma and tail. Comets only have a tail and coma when they are close enough to the sun to heat up.Full Answer >
Asteroids and comets have several things in common, including a relatively small size as compared to planets and a lack of a viable atmosphere. Asteroids range in size from a few feet to several miles in diameter. Comets are generally smaller, with a rocky core. Both comets and asteroids don't have enough gravity to keep atmospheres.Full Answer >