The bright spots that have made planetary scientists sit up and take notice of dwarf planet Ceres, has interested them even more as it is now suspected that they are creating a mini-atmosphere.
The bright regions, which are located at the bottom of Ceres’ Occator crater have been seen to sublimate material into space, creating a gas within the 92-kilometre-wide (57 miles) impact, according to observations by NASA’s Dawn spacecraft, which was launched to the dwarf planet in 2007. “If you look at a glancing angle, you can see what seems to be a haze, and it comes back in a regular pattern,” explains Christopher Russell, the Dawn spacecraft’s principal investigator. “The bright spots are possibly subliming, or they’re providing some atmosphere in this particular region of Ceres.”
The new piece of information backs up the consensus that Ceres’ bright spots are made of ice rather than some kind of salt. However, the features are still posing a major mystery – just like the rest of the dwarf planet, which Dawn has discovered to be 14.48 kilometres (nine miles) smaller than previously thought. Consequently, Ceres is around 4 per cent denser than initially understood.
Combined with numerous long and linear features, whose cause is unknown, Dawn has also uncovered a big mountain that the spacecraft’s team members have dubbed “The Pyramid”. “The Pyramid is about five kilometres (three miles) tall and 30 kilometres (19 miles) wide and features a flat top and strangely streaked flanks,” says Russell. “It’s got white sides on much of the surface and it looks like the material is cascading down from above.”
The results from Dawn are showing Ceres to be an active world. Some areas are less densely cratered than others, suggesting that there are geological processes that erase them. “Some regions look as if something has flowed over them, as if perhaps there was mud or slush on the surface,” says the Dawn spacecraft’s chief engineers and mission director Marc Rayman of NASA’s Jet Propulsion Laboratory in Pasadena, California.
From Ceres’ density, it’s thought that the dwarf planet contains a lot of water, with the majority of which is almost certainly in the form of ice. Some planetary scientists think that liquid water could exist beneath Ceres’ surface, hinting at the possibility of life.
“It is possible that the water systems associated with Ceres may harbour life and could be conductive to life more than some of the outer Solar System bodies,” says Russell. “So I would say we really do need to spend some time in probing the surface of Ceres and checking out its astrobiological implications.”