Earth is the third planet from the Sun. Known as the Blue Planet, over 70% of the Earth’s surface is covered with water, making it a unique planet in the Solar System.

Diameter: 12,600 km
Mass: 5.97 x 1024 kg
Composition: Iron, rock and water
Orbit: 150,000,000 km from the Sun
Distance from other planets: View matrix

Planet Earth is thought to have formed over four billion years ago. It is the fifth-largest planet in the Solar System and has just one satellite, known simply as the Moon. Earth is the only planet not to be named after a Greek or Roman god. The term Earth is a mixture of English and German words meaning ‘the ground’.

Earth consists of many layers. At the centre, there is an iron core surrounded by a liquid outer core. The mantle is composed of relatively solid rock, with the upper mantle and crust being divided into plates. These plates are always moving but when they touch each other earthquakes occur that can be felt on the surface. It is thought that originally the surface of Earth was molten and then cooled to form a crust.

Water covers 70% of the Earth’s surface and is on average four kilometres deep. The atmosphere is mainly composed of nitrogen and oxygen and plays an important role, as it is responsible for protecting us from the Sun’s harmful rays and from rogue meteors. There are many topographical features found on Earth both above and below water, such as mountains, volcanoes, canyons, deserts and plains. On land, Mount Everest in the Himalayas is the highest mountain, standing at 8.8 km above sea level. The Mariana Trench in the Pacific Ocean is the deepest crevice, measuring 10.9 km below sea level.

Earth orbits the Sun every 366.26 days. It takes 24 hours for it to rotate on its axis. This is how long it takes before the Sun is back at the position where it started and gives us the basis of a day. The Moon and Earth are tidally locked, which means that the Moon completely rotates in the same time it takes to orbit Earth. Because of this, the same side of the Moon is always seen from Earth.

The planet is also on an axial tilt which gives us seasons. If the North Pole is closer to the Sun, it is summer in the northern half of Earth and winter in the southern half. When the South Pole is pointing towards the Sun, it is summer in the southern hemisphere and winter in the northern hemisphere.

Many images of Earth have been captured from space and this data helps us to understand our environment and to be able to predict the weather and tides, among other things.

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