Dynamics of the Earth

The Big Bang theory holds that the universe is about 13.7 billion years old. However, the solar system including our home planet Earth was formed only 4.5 billion years ago when a solar nebula made of dust and gas—mostly hydrogen and helium—was accreted to form larger bodies. The Earth is composed of approximately spherical layers as are the other terrestrial planets orbiting the Sun, namely Mercury, Mars and Venus. The central core of the Earth is mainly composed of the heavy elements iron and nickel. The mantle and the thin crust, on the other hand, are mainly made up of the lighter elements oxygen, silicon and magnesium.

Despite cooling continuously, the Earth still retains much of its original heat. At its centre the Earth reaches temperatures of 6,000 to 7,000°C. The reason why our planet has not solidified completely since its formation is the heat-producing decay of radioactive elements. In this way an enormous dynamic results in the centre of the planet: the liquid iron in the outer layer of the core circulates and these convection currents are responsible for the magnetic field of the planet. This field is a shield high above the Earth’s surface sheltering us from hazardous particles of the solar wind. Likewise, the Earth’s mantle is characterised by large-scale convection currents, which are responsible for the movement of the tectonic plates and thus determine the occurrence of mountain ranges, volcanoes and earthquakes.

The fact that life could develop on Earth is due to a series of favourable circumstances. If the Earth were located closer to the Sun, all the water would have evaporated, whereas if it were further away all the water would have frozen. Furthermore, our planet has an atmosphere, which protects us from the harmful ultraviolet (UV) radiation of the Sun.