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Diameter12756 km
Mass5.97 x 1024kg
Volume1.08 x 1021 m3
Average Distance from Sun150 x 106km = 1 AU
ColourBlue and Green
ranges from -50°C to +40°C
AtmosphereNitrogen (78%)
Oxygen (21%)
Argon (0.9%)
Small amounts of carbon dioxide, hydrogen and others
Some water vapour
Length of Day23.9 hours
Length of Year365.25 days
No. of MoonsOne
Gravity9.81 N/m/s2

The Earth's oceans from space

Earth is the third planet in our Solar System, and as far as we know it is the only planet in the Universe that has living things on it. 71% of the Earth's surface is covered by water.

Earth has only one moon, but it also has another ‘companion’, Asteroid 3753(1980 TO) that passes close to the planet.

Earth is a changing planet, with many active volcanoes. It has also been hit by meteorites from outer space, just like the other planets. Meteorite strikes cause craters like those seen on the Moon, but on Earth they are washed away over thousands of years by rainfall and rivers. The Moon has no flowing water so they stay there forever. About 100 craters have been found on the Earth.

At the centre of the Earth there is a solid ball made of metal called the inner core. Around this is an outer core which is so hot that the metal is a liquid.

The Northern Lights, as seen from the Space Shuttle The next layer is called the mantle, and this is made of molten rock. This is what we see as lava when volcanoes erupt. Finally there is an outer layer called the crust which is made of solid rock. This is the surface of the Earth that we stand on.

The Earth has a magnetic field a bit like a bar magnet. Particles from the Sun blow past the Earth in the "solar wind", but some are caught in the magnetic field and pulled down into the atmosphere where they glow and are seen as the Northern and Southern Lights.

Planets Introduction



The Moon










Extra-Solar Planets

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Authors: Carolyn Brinkworth and Claire Thomas

Last updated: July 2001