April 2010 is the 40th Anniversary of Earth Day.
Earth Day is an annual event that aims to inspire awareness of and appreciation for our environment. There are two different observances of Earth Day, both held annually during spring in the northern hemisphere. The United Nations celebrates Earth Day each year on the vernal (March) equinox; while a global observance in many countries is held each year on 22 April.
Facts about Earth
Age: 4.6 billion years old (Life as we know it, has only existed on the planet for the last 150 million to 200 million years)
Position: 3rd planet from the sun.
Size: 5th largest planet in our solar system.
Diameter: The Earth has an average diameter of 12,742 kilometers. (7,926 miles)
Earth is the only planet in the Solar System to have water in its three states of matter: as a solid (ice), a liquid (sea, rain, etc.) and as a gas (clouds).
The length of time it takes for Earth to orbit the Sun is 365 and a quarter days. To make up this extra quarter which isn't counted at the end of a year, we have an extra day every four years on 29th February.
Earth travels through space at 66,700 miles per hour.
The centre of the Earth, its core, is molten. This means that it is liquid rock which sometimes erupts onto the surface through volcanic eruptions. This core is 7,500°c, hotter than the surface of the Sun!
Earth is the only planet in the Solar System not to be named after a mythical God.
Only 29% of the surface is actually 'earth.' The rest of the planet's surface (71%) is made up of water.
