Difference between Comet and Asteroid

There are several important differences between comets and asteroids, although the difference is not absolute. The main difference is that the tail of the comet, while asteroids do not. It is also important that comets often have very elongated orbits, sometimes moving up to 50,000 AU (Astronomical Units, or Earth-Sun distance) or more of the sun, while comets and short-term travel in the Since the outer planets before returning to the solar system. Asteroids tend to have more circular orbits, and merged into zones, like the asteroid belt between Mars and Jupiter and the Kuiper Belt beyond Neptune.

The tail and coma (atmosphere) of comet generated by solar heating, evaporating substance (volatile with low boiling point) on the surface of a comet, especially the ice and retrieves all around the comet. As the solar wind carries the material evaporates and forms a tail. Even if you can imagine, goes beyond the tail of a comet in the direction is an empty spot, so there is no wind resistance because it happened. Instead, the tail always points away from the sun to change the direction of its comet orbits the sun and the solar system is tilted backwards.

There are many asteroids comets. Since 2008, there are only about 3572 known comets, and millions of asteroids known. Most comets are believed to originate from a position far removed from the sun, especially in the Oort cloud, suggesting the tape material orbiting 50,000 AU from the sun. Thus, comets are composed of a few solar system objects, which rotate much closer to the sun. The reason this ice on them in large numbers, they spend most of their time away from the sun, where ice and shared the sun's rays are not strong enough to burn.

However, the majority of asteroids in the asteroid belt on the line of snow, "" solar system, which means that the surface is dry as a bone - all the ice has long since evaporated. Almost everything in this line of snow is dry, with the Earth (and years to March) is an important exception. As the Earth is in the snow line, we believe that most of its original water can be deposited by the comet. Additional water were produced chemoautrophic bacteria that can produce water in the atmosphere of hydrogen sulphide and carbon dioxide.