The core of Earth was warmed up to the temperature of 6 thousand degrees Celsius, it is one thousand degrees more than the previous estimates; it allows to explain existence of a magnetic field at our planet that was difficult earlier. The lithosphere of Earth consists of three layers — crust, a cloak and a core. Studying of a core and cloak layers directly is impossible in practice because of deep water on which their breeds lie. Therefore scientists investigate properties of a subsoil of Earth, watching laboratory experiments with an ultrahigh pressure and temperature. The scientists from the Commissariat of nuclear power of France in Grenoble could calculate temperature of firm part of a core of Earth, having tracked how iron behaves with an ultrahigh pressure. For this purpose scientists developed an original technique, which allows illuminating an alloy in the camera of a high pressure with help of x-ray radiation. As scientists explain, their technique allows learning an aggregate state of an alloy, whether there was it liquid or remains a firm body. Similar data are necessary for studying of behavior of a matter of a core as temperature of melting and other properties of iron cardinally change with an ultrahigh pressure. The scientists used the technique for measurement of properties of a slice of iron, which was squeezed on 2,2 million atmospheres in a diamond anvil and is heated to 4,5 thousand degrees Celsius by means of a laser beam. Scientists used these data for temperature calculation in firm part of a core pressure in which reaches 3,3 million atmospheres. To their surprise, temperature in it reached 6-6,5 thousand degrees, that is one thousand more than the previous estimates. According to the geologists, the new assessment of temperature will well be coordinated with other data on the device of a planet and allows explaining why the core of Earth generates a magnetic field.