Comets are the astronomical bodies of variable sizes which are dominant in space and are often considered as the giant dirty snowball. It is comprised of a mixture of substances such as ice, dust, and gases such as carbon dioxide (CO₂), ammonia (NH₃) and methane (CH₄). These comets usually have an average size of about 750 meters to about 20 kilometers in terms of diameter. These comets can sometimes enter into the earth's atmosphere due to the gravitational pull of the earth and can cause massive destruction on earth like the mass extinction event or the meteoric impacts. When they move in the earth's atmosphere, it forms a long tail.
