Ahuna Mons is seen in a computer simulation generated using Dawn data. The elevation has been exaggerated by a factor of two. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI


Ahuna Mons, the mysterious mountain on dwarf planet Ceres, is a giant ice volcano dome unlike anything seen so far in the Solar System, according to data from NASA’s Dawn mission.

The Dawn spacecraft has been studying Ceres since entering its orbit in March 2015, and one of the most interesting features it has recorded is a 4km-high mountain named Ahuna Mons.

New analysis led by Ottaviano Ruesch of NASA's Goddard Space Flight Center has concluded that the mountain is likely to be volcanic in origin.

In fact, Ahuna Mons is thought to be a cryovolcanco, meaning a volcano that erupts a watery liquid, and this revelation, if true, could point to an active geological past.

"This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past," says Ruesch.

Further analysis of Dawn data has suggested that Ceres may have a weak, temporary atmosphere.

Its GRaND (gamma ray and neutron) detector picked up signs that electrons from the solar wind - charged particles that stream from the Sun’s atmosphere - were accelerated to very high energies over a period of six days on Ceres.

This could be explained as atmospheric molecules on the dwarf planet interacting with the solar wind.

Dawn has also recorded a range of craters on Ceres of different shapes and sizes, suggesting that the dwarf planet’s crust is a mixture of rock and ice, rather than solely one or the other.

The study also compared the ratio of some craters’ depths to their diameters and concluded that some crater relaxation may have occurred.

This ‘relaxation’ refers to surface features eventually flattening out and changing shape.


Both these revelations suggest that Ceres' crust is not uniform, and that the dwarf planet has a complex geological history.