Earth

From space our home planet, Earth, appears to be mainly blue in colour. This is because of the colour of the oceans which cover over two-thirds of its surface. The land areas, or contenents, cover less than a third. the layer of air above the surface is thin, but makes life on Earth possible.

A number of things make Earth different from the other planets. It is covered with great oceans of water, and its atmosphere contains lots of oxygen. The atmosphere also acts like a blanket, holding in enough of the Sun's heat to keep Earth at a comfortable temperature. The water, the oxygen and the temperature make Earth a suitable place for living things - atleast one-and-a-half million different kind of plants and animals.

The changes in weather that we call the seasons happen because of the way Earth's axis is tilted in space. Because of this tilt, a place leans more towards the Sun and is warmer at sometimes of the year than at others. It is this that causes the changing season. The place tilted towards the Sun has summer, while the place leaning away has winter.