formation of the Earth

The Solar System was created when the gas cloud left over from a giant supernova explosion started to collapse in on itself and spin. About 4.55 billion years ago there was just a vast, hot cloud of dust and gas circling a new star, our Sun.

The Earth probably began when tiny pieces of space debris (called planetesimals) began to clump together, pulled together by each other's gravity. As the planet formed, more space debris kept on smashing into it, adding new material. This debris included ice from the edges of the Solar System.

fig. 1 - When the Earth formed from a whirling cloud of stardust, the pieces rushed tugether with
such force that the young planet turned into a fiery ball. It slowly cooled down,
and the continents and oceans formed.

About 4.5 billion years ago, a rock size of Mars crashed into Earth. Splashes of material from this crash clumed together to form the Moon. Also, this collision made the Earth very hot.

For a long time the surface of the Earth was a mass of erupting volcanoes. Iron and nickel melted and sank to form the core, while aluminium, oxygen and silicon floated up and cooled to form the crust.