The Online Library of Knowledge

Planet Earth

You are here: Earth > Planet Earth

Planet Earth

The Earth, showing its internal layersThe Earth, showing its internal layers The Earth is a spinning ball of rock and metal. It is one of eight planets that orbit, or circle, our nearest star, the Sun. Its surface is made up of oceans and land masses called continents. A layer of air called the atmosphere surrounds the whole planet. The Earth’s outer layer, the crust, is a thin, rocky shell. Beneath the crust lies the mantle, a thick layer made of hot, dense rock. At the very centre of the Earth is its core, a ball of metal, liquid on the outside, solid on the inside. Earth’s outer shell, called the lithosphere, made up of the rocky crust and partly molten upper mantle, is broken up into a number of large slabs of varying shapes and sizes, called tectonic plates. They are constantly on the move.

The Moon orbits the Earth, which orbits the SunThe Moon orbits the Earth, which orbits the Sun

The Earth in space

The Earth orbits the Sun, our local star. It speeds along at about 30 kilometres (19 miles) per second, taking 365.26 days (a year) to complete one orbit. As it goes, it spins on its axis like a top once every 24 hours. This makes the Sun appear to rise at dawn, pass across the sky and set at dusk, giving us day and night. The Earth is itself orbited by the Moon, which takes 27.3 days to go round it. Our closest neighbour in space, the Moon measures 3475 kilometres (2160 miles) across, about a quarter the width of Earth.

See also in Space

The Earth orbits the Sun at a distance where temperatures are just right to maintain liquid water on its surface. This is sometimes called the "Goldilocks zone"—neither too hot nor too cold, but just right.

© 2020 Q-files Ltd. All rights reserved. Switch to Mobile