The Earth is the largest of the inner planets. Its surface is made up of continents, oceans and polar ice caps. It is the only planet on which liquid water exists. The interior of the Earth is made up of a solid inner core, a fluid outer core, a rock-like mantle and a crust. The Earth is surrounded by a magnetic_field, the magnetosphere, which extends far out into space. This magnetic field is caused mainly by inner electrical currents.
The magnetosphere traps electrically charged particles from the solar_wind, which are collected mainly in the Van_Allen_Belt. The Earth's atmosphere is made up mainly of nitrogen and oxygen. It is divided into several layers with different temperatures. The ozone layer is very important, as it protects us from the dangerous ultraviolet_radiation of the Sun.
The Earth is accompanied by the Moon. As the Moon takes 27. 3 days both for one rotation on its own axis and for one orbit around the Earth, it always has the same side facing the Earth. During its orbit its appearance changes because it is illuminated to varying degrees by the Sun. This is observed by us as the phases_of_the_Moon.
The surface of the Moon consists of dark plains (maria) and highlands (terrae) with craters. The Apollo 11 mission brought man to the Moon for the first time.
