   A comet is a relatively small solar system body that orbits the Sun.
   Comets are made of ice, dust and small rocky particles.
   Examples of some comets are Hale-Bopp, Swift-Tuttle, Hyakutake, Halley, Shoemaker-
    Levy 9, etc.
Halley"s Comet
   It is known as a periodic comet (or short term comet) because the time it takes to orbit the
    Sun is less than 200 years.
   It can be seen with the naked eye from Earth every 76 years.
   It last appeared in the inner Solar System in 1986 and will return again sometime in 2061.
Comet Shoemaker-Levy 9
   In July 1994, the Shoemaker-Levy 9 comet broke apart and collided with Jupiter.
   Shoemaker-Levy 9 was originally located by astronomers Eugene M. and Carolyn
    Shoemaker and David Levy in March 1993.
   It is located at the center of the Solar System.
   It is the closest star to the earth.
   It is spherical in shape.
   It consists of hot plasma interwoven with magnetic fields.
   It is primarily composed of the two gases hydrogen and helium.
   The huge amount of energy produced by the Sun is created in its core by a process known
    as nuclear fusion. During this process four hydrogen nuclei are combined into one helium
   Its atmosphere is composed of three layers (Photosphere, Chromosphere and Corona).
    The part of the Sun that we see is the layer of its atmosphere known as the photosphere.
    Above the photosphere a red coloured layer called as Chromosphere is present. Solar
    winds are ejections of plasma (extremely hot charged particles) that originate in the layer of
    the Sun known as the corona.
   It is classified as a yellow dwarf star.
   Its rotation is opposite in direction from that the Earth"s rotation; that is, the Sun rotates from
    west to east instead of east to west.