The Earth is the greatest on weight, density and diameter from all zemlepodobnyh planets. Is thirds planet from the Sun in Solar system. At present is a unique planet known to mankind occupied by reasonable beings. The Earth has been formed 4,54 billion years ago after that has found the companion – the Moon.

The colour image from mission of Apolon 17

By calculations life on a planet has arisen 3,5 billion years ago. Since then the planet has strongly changed: atmosphere and others abioticheskie factors has changed. It has occurred at the expense of growth of aerobic organisms and formation of an ozone layer which protects a planet from solar radiation. The earthen bark consists of several tectonic plates, which in due course dvizhutsja on a surface. About 71 % of all surface of a planet it is covered by water, other part is divided into islands and continents. The internal part of the Earth consists of the iron kernel, covering its liquid external kernels and cloaks (rather firm layer).

The Earth co-operates in space with the natural companion and the Sun. For 365.26 days the planet does a complete revolution round the Sun. The Earth is under an inclination of 23,4 degrees to the orbital plane, at the expense of it seasonal changes on a planet are observed. The period of the given changes makes Tropical year (365,24 solar days). The unique companion of a planet – the Moon, has started to rotate on a circumterraneous orbit 4,53 billion years ago. Thanking its rotation the axis of an inclination of the Earth is stabilised, there are inflow and otlivy, planet rotation is slowed down.