What are Comets

# A comet is an icy small Solar System body that, when passing close to the Sun, heats up due to the effects of solar radiation and the solar wind upon the nucleus and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail.

# Comets have highly elliptical orbits, unlike the planets which have near-circular orbits.
They are made of frozen gases (water, ammonia, methane and carbon dioxide) which hold together small pieces of rocky and metallic minerals.

# Short-period comets (orbital period of a few hundred years) originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune.

# Longer period comets, with orbits of thousands of years, come from the more distant Oort Cloud.

# Oort cloud is a giant shell of icy bodies that encircle the solar system occupying space at a distance between 5,000 and 100,000 AU.

# One of the larger comets is the Halley’s Comet. The orbit of Halley’s Comet brings it close to the Earth every 76 years. It last visited in 1986.