Comets are like ice cubes floating in the solar system. It has been theorized by the astronomer said. After the birth of the solar system Outside gas nor being drawn into the center of gravity as well as contrary to the cloud consisted of ice cubes. Which is about the distance from the sun to a distance of about one light year and a chunk of ice the size small is no less than a million loaves of comets are composed of stone dust, a lot of ice, carbon dioxide, ammonia, methane, water, etc. at any given time. The strong interference from other planet or star, these ice cubes will fall into orbits closer to the Sun and various compounds containing a block of ice, it would have been heated and ionized. These ions may be the solar wind. Pushed to the head and tail of the comet's orbit around the sun. And a high elliptical orbit is very large, with the Sun located at the focal point of the ellipse that we are likely to see. The comet was only when the comet moves into the inner solar system where Earth is. Only Some comets have orbits. Not very large We see the comet's orbit again classified as short-period comets orbit. Most comets with orbital periods longer than 200 years to be a long-period comets orbit. Comets with orbital periods are short sequences within the solar system.