Asteroids - through cold, lifeless body. In the distant last their bowels could be warm and even hot due to radioactive or any other heat sources. Since then, they have long cool. However, internal heat never warmed surface: the flow of heat from the interior was very small. The surface layers remained cold, and only clash from time to time caused short-term local heating.

The only permanent source of heat for asteroids remains the Sun, far and therefore the heat is very bad. Heated asteroid radiates into space heat energy, and the more intense than stronger from hot. Losses are covered absorbed part of the solar energy incident on the asteroid, which decreases inversely as the square of heliocentric distances. Based on these considerations and using the Stefan-Boltzmann law, got that With the-asteroids in the distance was 2.76 A. that is from the Sun (the average distance of Ceres) maximum temperature in sunflower reaches 170 To, and on distance of 5.2 a. E. (average distance of Trojans) - 125 K. Bright's-asteroids warm worse because of the large albedo they absorb primerno 10% less solar energy. Such bright asteroids as Vesta, absorb about 20% less solar energy.

If the average temperature throughout the illuminated surface, will get that asteroids spherical shape the average temperature of the illuminated surface 1.2 times lower than the temperature in sunflower point.

Due to the rotation of the asteroid temperature of their surface is changing rapidly. Sun-warmed surface cool down quickly because of the low thermal capacity and low thermal conductivity their constituent substances. In rezultate on the surface of the asteroid runs a heat wave. She quickly fades out with depth, not penetrating into the depth of even a few tens of centimeters. Deeper the temperature is almost constant, the same as in the depths of the asteroid on several degrees below average temperature of the sunlit surface. The bodies moving in the ring of asteroids, it can be roughly equal to 100-150 K.

No matter how little the thermal inertia of the surface layers of the asteroid, all the same, to be quite simple, it must be said that the temperature does not have time to take the equilibrium value with changes in lighting conditions. The morning side, not having time to warm up, vsegda a little bit colder than it should, and the evening party is a little bit warmer, not having time to cool down. Relatively sunflower point there is a light asymmetry in the distribution of temperatures.

Maximum thermal radiation of asteroids lies in the region of wavelengths of the order of 20 microns. Therefore, their IR spectra should look like continuous radiation with intensity, monotonically decreasing in both sides of the maximum. This is confirmed by the observations of 10 Hygieia, 39 Leticia and 40 Harmony conducted O. Hansen in the range of 8 to 20 microns. However, when Hansen tried on the basis of these observations to determine the temperature of the asteroids, it was higher than estimated (about 240 K), and the reason for this is still not clear.

The low temperature of bodies moving in the ring of asteroids, means that diffusion in the asteroid substance "frozen". The atoms are not able to leave their seats. Their relative position remains unchanged for billions of years. Only this way we can study the characteristics of the location, which emerged in the dust before entering the asteroid, to explore the subtle channels - tracks and broken particles of cosmic rays in the asteroid substance that was once on poverhnosti these bodies, and then immured in meteorites, discover on the surface of individual particles extracted from meteorites, tiny createrock micron sizes, created facing them dust. Isolation is able to bring to life the diffusion only those asteroids, which are moving in orbits with small perihelion distances (so much closer to the Sun), but only in the surface layers and for a short time. Traces of such diffusion undoubtedly carries the surface of the asteroid substance Icarus. Because at perihelion surface of the car is heated to about 1000 K.

The substance of those meteorites that were approaching the Sun, for example, meteorites have Washougal, Old Pesano and other (as judged by exploring the orbit of meteorites), must also bear the traces of such diffusion traces short but repeated heating. These tracks are not yet identified, but may be thawed at the time of diffusion caused abnormally short (annealed) tracks from cosmic rays found in the meteorite, melalahti Soviet researchers B. N. Perelygina and others.