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 Sun and other starsEarth and Space:

Convection zone

Radiation zone

Core

Solar Flare

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

Alpha Centuri Our Sun

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

Earth and Space:The Sun and other stars

Galaxy

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

• We see moons around the planets, including our Moon, in the same way

Earth and Space:The Sun and other stars