How the world began

How did the solar system begin?
Scientists think that our solar system began to form about 5,000 million years ago. The Sun and the nine planets came from a cloud of dust and gas. Some scientists believe that the centre of this cloud contracted to form the sun. Then gravity pulled the planets from the rest of the cloud.

What is the Earth?
The Earth is a huge rocky ball about 12,750 km in diameter. It is one of a group of nine planets which orbit the Sun. This group is the solar system. We think the Earth is the only planet with life on it. The centre of the Earth is white-hot. About 4,600 million years ago the Earth’s surface began to form. Then came the oceans and the continents. The continents used to look very different from today. Our planet is still changing. Some continents are moving nearer to each other and some are moving apart.

When did the life on Earth begin?
The first animal life probably appeared 4,000 million years ago. These were single-celled animals like amoeba. The first sea creatures and flying insects appeared under 1,000 million years ago. Human beings appeared quite recently – only 65 million years ago!