1) The Solar System consists of:
- the Sun
- planets
- natural satellites
- asteroids
- meteors
- comets
(b) It is a star because it gives out light and heat. It is the only star in
the Solar System.
(c) The Sun is the biggest body in the Solar System. It consists af a ball
of hot gases.
Planets Of The Solar System
1) Planets are bodies in the Solar System that move round the Sun.
(a) A planet does not give out its own light and heat.
(b) We can see other planets from Earth because they reflect light
from the Sun.
2) There are nine planets in the Solar System:
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
- Pluto (Since 24 August 2006, Pluto is classified as a dwarf planet.)
own axis.
- The planets that are nearer to the Sun take a shorter time to move around the Sun because they have smaller orbits.
- The planets that are further from the Sun take a longer time to move around the Sun because they have bigger orbits.
- For example, Mercury takes about 88 days to move around the Sun while Neptune takes about 165 years.
the distance between Jupiter and the Sun is longer than the distance between
the Earth and The Sun.
5) The time taken by the planets to make one complete movement round the Sun
depends on their distance from the Sun.
Positions of planets from the Sun
Natural Satellites
1) Some planets have large bodies that orbit around them. These bodies are
called natural satellites.
2) The Moon is the only natural satellites of thw Earth. It is smaller than the
Earth. It orbits round the Earth and the Sun.
3) Mercury and Venus do not have their own natural satellites. Some planets
have more than one natural satellites.
4) Natural satellites do not give off light or heat. They reflect light from the
Sun and can be seen from Earth.
Asteroids
1) Asteroids are bodies made up of metals and rocks.
2) Most asteroids are found in the asteroid belt between the orbits of Mars
and Jupiter.
3) More than 10000 asteroids and more are discovered every month. Ceres
is the first asteroid to be discovered. It is the largest asteroid.
4) Some asteroids come near the orbit of the Earth. Someday, one of these
asteroids could hit the Earth.
5) An asteroid hit Earth 65 million years ago in Mexico.
Meteors
1) A meteoroid is a piece of rock or metal that floats in space.
(a) Meteoroids come in many shapes and sizes but most of them are small.
(b) There are millions of meteoroid in space.
2) When a meteoroid enters the atmosphere of the Earth, the friction between
the meteoroid and the air causes it to glow and give off light. It is called a
meteor.
Meteor
3) A meteor looks like a streak of bright light that is seen across the night sky.
It is also commonly called a shooting star.
4) (a) A meteor that has landed on the surface of the Earth is called a meteorite.
(b) When a meteorite hits the Earth, a crater or a hole is formed in the ground.
Comets
1) A comet is a lump of ice which consists of frozen gases and dust.
2) Comets move around the Sun in long orbits. They take years to complete
one orbit.
3) Most comets spend their time beyond the Solar System. When they enter
the Solar System and come near the Sun, they can be seen from Earth.
4) When a comet comes near the Sun, the heat of the Sun causes the ice at its
centre to melt. This causes the comet to glow and a long tail of gas and dust
is visible.
5) The most famous comet is Halley's Comet.
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