The Solar System

1. Planets are large round objects in space that move around the Sun.
2. They are nine planets in the Solar Systems. They are:

3. The Sun is at the centre of the Solar System. All the planets in the Solar System move 
    around the Sun. 
 4. The Sun is the only star in the Solar System. A star is an object in space that gives out
   light and heat.
 5. The Sun ois also the biggest object in the Solar System.
 6. All planets in the Solar System move around the Sun in their respective orbits.
 7. The gravitational force between the Sun and each planet keeps the planets from moving 
    out of their orbits.
 8. Besides the nine planets, other components of the Solar System are natural satellites,
asteroids, meteoroids and comets.
 9. Natural satellites are objects that move around the planet.
10. The Moon is an example of a natural satellite.It movesaround the Earth.
11. All plAsteroids anets,except Mercury and Venus,have their own natural satellites. 
12. An asteroid consists of rocks and metals.
13. Asteroids have different shapes and sizes.Most asteroids have a diameter of more than 
14. Most asteroids are found in the orbit between Mars and Jupiter.
15. A meteoroid is a piece of rock that is floating in space.
16. There are millions of meteoroids in the Solar System. Most of them are small.
17. Every day, millions of small meteoroids enter the Earth's atmosphere from space.
18. When the meteoroid enters the Earth's atmosphere, it burns very brightly. Friction between
    the meteoroid and the air causes the meteoroid to burn up. It is then called a meteor.
19. A streak of bright light appears in the sky when a meteor burns while entering the Earth's
   atmosphere at night.
20. A meteor that has landed on Earth is called a meteorite.
21. When a big meteor hits the Earth's surface, a big crater will be formed.In Arizona, USA, 
    there is a crater that is 12 km wide and 200 m deep.
22. A comet is made of pieces of ice in  space. It is made of water, dust and frozen gases.
23. Examples of comets are the Halley's Comet and Hale-Bopp's Comet.
24. Comets move around the Sun in a long orbit.
25. Halley's Comet takes 76 years to complete one orbit.It is expected to come near the Earth
   again in the year 2062.