PLANETARY SYSTEMS: OUR SOLAR SYSTEM

Refresh What is the name of the star in our planetary system?

4 The Solar System

The Earth, our planet, is part of the planetary system called the Solar System. It consists of a central star and all the celestial bodies that orbit around it. This planetary system belongs to galaxy called the Milky Way.

In our Solar System there are many different celestial bodies. The central star is called the Sun, which is big sphere of gas that emits light and heat and allows life on Earth. All the planets in the Solar System orbit around the Sun. In the past, people used to think that the Earth was the centre of the Solar System.

Planets in the Solar System have got different compositions. Some are made of rock, like the Earth and Mars and others are made of gas, like Jupiter or Saturn.

Some planets have got satellites. The Earth has got only one satellite: the Moon. Jupiter and Saturn have got more than 60 different moons. Other planets, like Mercury, haven’t got any satellites. This is because it is too close to the Sun and as a result of its gravity.

There are satellites that are so big that they are similar in size to planets. Ganymede, one of Jupiter’s moons, is bigger than Mercury.

1 Complete and complete the sentence in your notebook. The Earth belongs to the (a)…, which is part of the (b)… .

2 Work in pairs. Do you remember the name of the eight planets that orbit around the Sun in our Solar System? Draw a diagram and draw them in their correct position.

3 There is a dwarf planet that orbits around the Sun and is at the far end of the Solar System. It used to be considered a planet. Write its name.

4 Look at the diagram. One year is the time each planet takes to orbit around the Sun. Decide which planet has got the shortest year and which planet has got the longest year.

5 Which of these sentences is false?

a) Ganymede, one of Jupiter’s moons, is bigger than Mercury.

b) Gravity is the force that controls the Solar System.

c) The conditions and characteristics of Neptune make it possible to find life there.

d) People used to think the Sun orbited around the Earth.

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In the past, people used to think that the Earth...

6 Copy the following celestial bodies in your notebook. Next to each one, write the correct type of celestial body.