While being compared to the solar system, comets are tiny. Like asteroids they are bits of debris left over from when the Universe first started. According to one widely accepted opinion, comets are as old as the Universe and were once the blocks that produced Neptune and Uranus.

Comets are pieces of dirty ice , dust, and grit. The icy part of the comet, the nucleus, is covered by a cloud of glowing gases, called the coma. This coma bends into a tail, which can be broken up into streamers, with twists and swirls. The longest comet nucleus ever recorded had a measurement of 42 miles (67.6 km). The shortest comet nucleus measured 0.3 miles (0.5 km)..

Three things happen when a comet heads toward the Sun.

	When a comet is far from the Sun but speeding toward it, the comet is solid, has no tail and races through space like a snowball.
	As the comet gets closer to the Sun, the Sun’s powerful rays start to melt the comet. Dust and gas start to stream out creating a cloud called a coma.
	The Sun’s solar wind, which is a constant stream of particles, blows some of the comet out behind it to make a spectacular tail.

The tail of a comet can be millions of miles long.  It is very thin.  Stars can be seen through it. Some comets are very bright. Usually, bright comets have two tails. First there is a bluish tail that is straight and stretches behind the comet pointing away from the Sun. This tail is blown off the comet by solar wind and gas. Sometimes there can be a yellowish-white dust tail which bends out in another direction and traces out the path of the comet’s orbit. Comets can have more than two tails. A comet known as DeCheseaux comet fanned out like a peacock and had seven tails!

There are two groups of comets. There is a short period comet. It has an orbital period of less than 200 years. Long period comets have orbital periods for millions of years. Short period comets are part of the inner solar system. The Kuiper Belt is the source of short period comets. The long period comet, when farthest away from the Sun, can be halfway to the nearest stars. The Oort Cloud, an area beyond the orbits of Neptune and Pluto, is a source of long period comets.

Comets have been watched and recorded for thousands of years but they have not always been understood. Centuries ago they were called "hairy stars" and people regarded them as bad omens. People also thought comets would cause plague, war, and death! It was once thought comets were made of vapor that had risen from the Earth.

It was not until the 17th century that astronomers began to understand comets. Edmond Halley, an English scientist and astronomer, showed that comets observed in 1531, 1607, and the one he observed in 1682, were the same comet. He predicted it would return again in 1759, 1835, and again in 1910 and 1986. It became known as Halley’s Comet. He was the first to prove that some comets follow regular orbits that keep them returning to the vicinity of the Sun.

New comets are discovered each year. On the average, about five are discovered.   They can only be observed with a telescope because they are so faint. Between 1995 and 1997, a new comet came into view. It was the clearest comet for nearly a hundred years. Its name was Hale-Bopp.

I would like to learn more interesting facts about comets and hopefully, see one myself one day!

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