What is the difference between comet and asteroid?

There are several important differences between comets and asteroids, although the difference between them is not absolute. The primary difference is that comets have a tail while asteroids not. It is also important that comets tend to have extremely elongated orbit, sometimes passengers up to 50,000 AU (astronomical units or distances of the earth-Sun) or further from the Sun, although short-term comets travel to external planets before returning to the inner solar system. Asteroids tend to have multiple circular pathways and join in strips, such as an asteroid belt between Mars and Jupiter or Kuiper belt behind the orbit of the Neptune. comet. Then the solar wind removes evaporated materials and forms a tail. Although one can imagine that the tail reaches for a comet towards its travel, there is a vacuum space, so there is no resistance to the wind that causes it. Instead, the tail always shows from the sun and changes its orientation when the comet orbits the orbiting sun and is turned back to the outer solar sothe installations.

Many other asteroids are known than comets. Since 2008, only about 3,572 comets have been known, while there are many millions of asteroids. Most comets are assumed that they come from places very distant from the Sun, especially from the Oort Cloud, a hypotheted belt orbiting the material located approximately 50,000 AU from the Sun. Thus, comets consist of very few objects from the distant outer solar system that have orbits that bring them to the sun. The very reason why ice exists in such a large amount is that they spend most of the time very far from the Sun, where it is reed and the sun's rays are not intense enough to burn it.

On the contrary, most asteroids in the asteroid belt are located in the "snow line" of the solar system, which means that their surfaces are dry as a bone - all LEDs have been evaporated for a long time. Most of everything in this line the councilHu is dry, while the country (and ancient Mars) is the main exception. Since the country is within the snow line, it is believed that a large part of its initial water could be stored through the impacts of the comet. Other water was produced by chemoaurtrophic bacteria that can synthesize water from hydrogen sulphide and atmospheric carbon dioxide.