2. The Sun and other stars The Sun is a Star and a source of light for everyone on Earth The light from the Sun takes 8.3 minutes to reach us Like all stars, the Sun is a huge ball of very hot gas Earth and Space:

3. The Sun and other stars The surface temperature of the Sun is 5,700 0 C The centre of the Sun has a temperature of 15,000,000 0 C The Sun is made of: 71% hydrogen 21% helium 8% of all the other elements Earth and Space:

4. The Sun and other stars Earth and Space: Convection zone Radiation zone Core Solar Flare

5. THE SPEED OF LIGHT Light travels at 300,000,000 m/s It can travel form London to New York, and back again, 25 times in less than one second! Travelling at 1000 kph it would take a Jumbo jet 12 hours to do this journey once Earth and Space: The Sun and other stars

6. SEEING STARS Stars are luminous This means that they give out light The luminosity is a measure of the energy it gives out The amount of energy depends on: The size of the star The temperature of the star Earth and Space:

7. Red Orange Yellow White Blue-white The Sun and other stars Earth and Space: Stars come in different colours The colours have different temperatures 3,000 0 C 4,000 0 C 5,000 0 C 10,000 0 C 20,000 0 C

8. STARS AND GALAXIES Most of the stars we can see belong to our galaxy, the Milky Way A galaxy is a collection of millions of stars, held together by gravity Our galaxy contains 100,000 million stars Earth and Space: The Sun and other stars

9. Apart from our Sun, the nearest star to us is Alpha Centuri It is 40,000 billion (40,000,000,000,000 km) away It takes 4.3 years for the light to reach us When we look at Alpha Centuri we look at it as it was 4.3 years ago Earth and Space: The Sun and other stars

10. Alpha Centuri Our Sun Earth and Space: The Sun and other stars

11. It takes over 100,000 years for the light to reach us from the furthest star in our galaxy 1,000,000,000,000,000,000 km Earth and Space: The Sun and other stars

12. There are over 100,000 million galaxies in the Universe The nearest galaxy to the Milky Way is the Andromeda galaxy It takes over 2 million years for the light to reach us from the Andromeda galaxy It takes almost 15,000 million years for the light to reach us from the furthest galaxies When we look into space, we are looking back in time Earth and Space: The Sun and other stars

13. Earth and Space: The Sun and other stars Galaxy

14. SEEING PLANETS Planets do not produce their own light They are non-luminous We only see planets because light from the Sun is reflected off them and reaches us The Sun and other stars Earth and Space:

15. The further the planet is from the Sun, the less energy it receives The less energy it receives, the dimmer it appears Earth and Space: The Sun and other stars

16. We see moons around the planets, including our Moon, in the same way Earth and Space: The Sun and other stars