Asteroids

Asteroids are small rocky or metallic bodies that orbit the sun lying between the orbit of mars and Jupiter. Hundreds of thousands of asteroids exist in the solar system. Asteroids range in size from a few meters to over 500km. they are generally irregular in shape and often have surfaces covered with craters. They are also called minor planets. Ceres, Vesta, Hermes, Eros. Pallas, Juno etc.

• Vesta is the brightest asteroid
• Ceres is the brightest asteroids

Planets	Asteroids
They revolve around the sun in respective orbit.	They revolve around the sun lying between the orbits of mars and Jupiter.
They are larger.	They are smaller.
There are 8 planets.	They are large number of asteroids.

Comets

The broom shaped objects of a lump of ice that appear occasionally in the sky is called comet. They are also called tailed star. They revolve around the sun in highly elliptical orbit. They have bright head and luminous tail. The head is made up of various sized rock sand gases and the tail is made up of glowing gases and dusts. They have a central mass called nucleus and around which is called coma. The nucleus coma together forms a head.

• The comets move in highly elliptical orbit. So they sometime come much close to the sun and sometimes very far from the sun.
• When the comets come close to the sun, the ice crystals vaporize and gases glow which spread in the form of long tail away from the sun due to the effect of solar wind. In this way the tail of a comet is formed.
• They are like planets and reflect the light from the sun.
• Whenever they come close to the sun, they lose some of their ice, dusts and gases and ultimately converted into asteroid like pieces.
• A comet is not actually a star because it moves in highly elliptical orbit around the sun and it does not have light of its own and reflects the light from the sun.
• A comet is made up of frozen gases, dust particles and ice blocks. When a comet approaches the sun, the materials in it vaporize and due to the effect of solar wind long tail is formed. But when it goes far away from the sun, the vaporized materials start to condense and the tail becomes shorter.
• The comets are seen only after a long period of time. It is because they revolve around the highly elliptical orbit and take long time to revolve around the sun.
• The shoe maker levy was seen in 1993 which destructed when collided with Jupiter.

Some examples of comets are

Comets	First Appearance	Period of revolution
Halley's comet	240 BC	76 years
Temple Tuttle	1366 AD	33 years
Enke	1786 AD	33 years
Schwas man washman	1927 AD	15 years
Bennet	1969 AD	unknown
Shoemaker Levy	1992 AD	unknown

• Asteroids are small rocky or metallic bodies that orbit the sun lying between the orbit of mars and Jupiter.
• Planets revolve around the sun in respective orbit.
• Asteroids revolve around the sun lying between the orbits of mars and Jupiter.
• The broom shaped objects of a lump of ice that appear occasionally in the sky is called comet. They are also called tailed star.
• A comet is not actually a star because it moves in highly elliptical orbit around the sun and it does not have light of its own and reflects the light from the sun.