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:
The Sun and other stars
• The surface temperature of the Sun is 5,700 0C
• The centre of the Sun has a temperature of 15,000,000 0C
• The Sun is made of:
• 71% hydrogen
• 21% helium
• 8% of all the other elements
Earth and Space:
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
The Sun and other stars
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:
• Red
• Orange
• Yellow
• White
• Blue-white
The Sun and other starsEarth and Space:•Stars come in different colours•The colours have different temperatures
3,000 0C
4,000 0C
5,000 0C
10,000 0C
20,000 0C
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
• 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
• 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
• 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
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 starsEarth and Space:
• 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
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