Comets are snowballs composed of ice,rock and dust.Comets are formed farther from the Sun where ices would not melt. When a comet approaches the sun ,some of the ice in its nucleus (center) turns into gas .The gas shoots out of the sunlit side of the comet. The solar winds then carries the gas outward forming it into a long tail.
Astronomers divide comets into two main types ,long-period comets ,which take 200 years to orbit the sun ,short-period comets which complete their orbits fewer than 200 years. The two types come from two regions at the edges of the solar system. Long-period comets originate in the Oort cloud ,a cluster of comets far beyond the orbit of Pluto ,the short-period come from the Kuiper belt beyond the orbit of Neptune.
Our solar system most famous comet is probably the Halley's comet.Halley's comet has been spotted from earth every 75 years or so.
Asteroids are minor planets are basically broken pieces of unfinished planets and leftover debris from the formation of our solar system about 4.6 billion years ago . Most of the asteroids circle around the sun in a region called asteroid belt between Mars and Jupiter .The belt contains more than 200 asteroids larger than 100 kilometers in diameter.
Scientists estimate the asteroid belt also contains between 1.1 million and 1.9 million asteroids larger than 1 km in diameter and millions of smaller ones. Astronomers have found several large asteroids with smaller asteroids orbiting them.The largest asteroid is Ceres, which is 933 kilometers (580 miles) across.
Meteoroids are broken chunks of asteroids that resulted from collisions in the asteroids belt. when meteoroids plunge into earth's atmosphere they form bright streaks of light called meteors as they disintegrate .Some meteoroids reach earth and they become known as meteorites. Some meteoroids are fragments from bodies such as Mars or our moon that have been thrown into space by an impact.
A meteor shower is the result of an interaction between a planet such as Earth and stream of debris from a comet or other source.
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