Comets+and+Asteroids+-+by

Comets and Asteroids​! ====**__ASTEROIDS__** **Most Asteroids are remains from the start of the solar system. They orbit the sun or they are in the Asteroid Belt, between Mars and Jupiter. They can be a few hundred feet to a few kilometres in diameter. There are more than 100,000 Asteroids in the Asteroid Belt. These asteroids lie in a location in the solar system where there seems to be a jump in the spacing between the planets. Scientists think that this wreckage may be the remains of an early planet, which broke up early in the solar system. The chances of an asteroid colliding with Earth are very small. But some do come close to Earth, like Hermes (closest approach of 777,000 km). ** ====

==== ==== ====**__COMETS__** **A comet has an icy body that releases gas or dust. Most of the comets that can be seen from Earth travel around the sun in long, oval orbits. A comet consists of a solid nucleus (core) surrounded by a cloudy atmosphere called the coma and one or two tails. Scientists think that short-period comets come from a band of objects called the Kuiper belt, which lies beyond the orbit of Pluto. The gravitational pull of the outer planets can nudge objects out of the Kuiper belt and into the inner solar system, where they become active comets. Astronomers believe that comets are leftover debris from a collection of gas, ice, rocks, and dust that formed the outer planets about 4.6 billion years ago. Some scientists believe that comets originally brought to Earth some of the water and the carbon-based molecules that make up living things. ** ** Halley's Comet **** or Comet Halley is the most famous of the periodic comets and can currently be seen every 75–76 years. Many comets with long orbital periods may appear brighter and more spectacular, but Halley is the only short-period comet that is clearly visible to the naked eye. During it’s returns to the inner solar system, it has been observed by astronomers since at least 240 BC, but it was not recognized as a periodic comet until the eighteenth century when its orbit was computed by English astronomer Edmond Halley. Halley's Comet last appeared in the inner Solar System in 1986, and will next appear in mid 2061. **====