TNPSC Free Notes Physics In English – Other Bodies of the Solar System

இந்தக் கட்டுரையில், TNPSC குரூப் 1, குரூப் 2, குரூப் 2A, குரூப் 4 மாநிலப் போட்டித் தேர்வுகளான TNUSRB, TRB, TET, TNEB போன்றவற்றுக்கான  முறைகள் இலவசக் குறிப்புகளைப் பெறுவீர்கள்.தேர்வுக்கு தயாராவோர் இங்குள்ள பாடக்குறிப்புகளை படித்து பயன்பெற வாழ்த்துகிறோம்.

Other Bodies of the Solar System:

Besides the eight planets, there are some other bodies which revolve around the Sun. They are
also members of the solar system.
Asteroids:
There is a large gap in between the orbits of Mars and Jupiter. This gap is occupied by a broad
belt containing about half a million pieces of rocks that were left over when the planets were
formed and now revolve around the Sun. These are called asteroids. The biggest asteroid is Ceres
– 946 km across. Every 50 million years, the Earth is hit by an asteroid nearing 10 km across.
Asteroids can only be seen through large telescope.
Comets:
Comets are lumps of dust and ice that revolve around the Sun in highly elliptical orbits. Their
period of revolution is very long. When approaching the Sun, a comet vaporizes and forms a
head and tail. Some of the biggest comets ever seen had tails 160 million (16 crores) km long.
This is more than the distance between the Earth and the Sun. Many comets are known to appear

periodically. One such comet is Halley’s Comet, which appears after nearly every 76 years. It
was last seen in 1986. It will next be seen in 2062.
Meteors and Meteorites:
Meteors are small piece of rocks scattered throughout the solar system. Traveling with high
speed, these small pieces come closer to the Earth’s atmosphere and are attracted by the
gravitational force of Earth. Most of them are burnt up by the heat generated due to friction in
the Earth’s atmosphere. They are called meteors. Some of the bigger meteors may not be burnt
completely and they fall on the surface of Earth. These are called meteorites.

Satellites:
 A body moving in an orbit around a planet is called satellite. In order to distinguish them
from the man made satellites (called as artificial satellites), they are called as natural
satellites or moons. Satellite of the Earth is called Moon (other satellites are written as
moon). We can see the Earth’s satellite Moon, because it reflects the light of the Sun.
Satellite moves around the planets due to gravity, and the centripetal force. Among the
planets in the solar system all the planets have moons except Mercury and Venus.
 The Sun travelling at a speed of 250 km per second (9 lakh km/h) takes about 225 million
years to complete one revolution around the Milky Way. This period is called a cosmic
year.

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