If you were to view the Earth from space you would see blue oceans, white clouds and polar ice caps, and dark areas of land. It is the only planet we know that has life. Life on Earth only thrives because there is a balance between animals, which use up oxygen and release carbon dioxide; and plants, which take in carbon dioxide and produce oxygen. For all life to survive, a steady temperature is important: a few degrees hotter and the ice caps will melt, flooding large areas of land; a few degrees colder and crops will not grow. We need to be very careful not to disturb this delicate balance and turn our living planet into a barren desert such as Mars or Venus.

The Earth's crust contains over 2,000 different minerals. Only about 20 of these minerals are made up of different chemical elements. Just eight elements make up 99% of the Earth's crust.

The Earth's total land area is 57,268,900 square miles (148,326,000 km²), which equals 29% of its total surface. Compare this to the area of water on Earth - 139,668,500 square miles (361,740,000 km²), which equals 71% of the total surface of the Earth.

Earth is the only planet in the Solar System known to have liquid water (although the Moon is now shown to have ice water). Of all the water on Earth, 97% is saltwater. Only 3% is freshwater and two-thirds of this is frozen into ice. Only 1% of all the Earth's water is in lakes, rivers, or underground.

Highest mountain: Mount Everest, 29,000 ft (8,848 m) above sea level.

Deepest ocean trench: Mariana Trench, Pacific Ocean, 36,000 ft (11 km) below sea level.

There are about 700 active volcanoes. About 30 of them erupt each year.

About a fifth of the Earth's land surface is mountainous and a further eighth is covered in desert.

The largest freshwater lake is Lake Superior on the border between Canada and the USA. Its area is 31,800 square miles (82,400 km²). The Caspian Sea is the largest saltwater lake, or inland sea. It is about 144,000 square miles (372,000 km²) in area.

The oxygen in the Earth's atmosphere is produced by plants. About 70% of it comes from tiny plants, called algae, floating in the oceans. Plants also take in the carbon dioxide that animals breathe out.