The landscape of Ceres, a dwarf planet between Mars and Jupiter (the former moon of Phaeton), does not seem to be particularly diverse. Craters, relatively flat areas, lowlands - in a word, a standard space set. Against this background, Mount Akhuna looks like a real alien. This is the only such formation on Ceres. The mountain in splendid isolation rises five kilometers above the surface of the dwarf planet.
When Dawn first photographed Akhun, she puzzled scientists. On a dwarf planet, there is no movement of lithospheric plates, and the temperature of its interior is too low for magma to exist there. Mountains can appear after asteroid impacts (the central peak of the crater), but Akhuna is not even close to such a formation. And now, after going through all the options, the researchers came to the conclusion that Akhuna is a cryovolcano. Several factors speak in favor of this theory.
The shape of the mountain resembles a volcanic dome, characteristic cracks are observed on its top, and on the slopes there are lines that usually occur during rockfalls. At the foot of the mountain there is a fairly smooth area, along which streams of salt water apparently flowed down, which played the role of magma.
Of course, cryovolcanoes themselves are not new. They were found on Triton, Enceladus and Titan, apparently, they were also identified on Pluto. But the fact is that their existence there is explained by the tidal interaction, which heats up the bowels of these bodies. Ceres, on the other hand, dangles along the asteroid belt alone. But, obviously, this was not always the case …
The volcano could also be explained if it had formed at the dawn of the solar system, when the interior of Ceres was heated by the decay of radioactive elements. But Akhuna is much younger. According to various estimates, its age ranges from 70 to 250 million years. So, as is often the case in astronomy, the answer to one question spawned another.
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It is also worth noting that the Dawn apparatus, apparently, was able to confirm that there is indeed an atmosphere or traces of it on Ceres. For six days, its GRaND neutron and gamma ray spectrometer recorded bursts of electrons. This is usually recorded when the solar wind collides with the magnetosphere or atmosphere of a celestial body. But, as you know, Ceres has no magnetic field.
But back in 2014, the Herschel telescope recorded traces of water vapor on the dwarf planet. And on the surface there are traces of the ocean, which once, in the distant past, was filled with liquid water … The reserves of water (frozen) on the dwarf planet are very large! So Ceres is not a geologically dead body at all, as it might seem at first glance. Some activity is definitely still taking place in its depths …