Scientists say a mysterious mountain on the dwarf planet Ceres was apparently once an ice volcano, spewing salty water and mud instead of lava.
They also say Ceres has patches of water ice that can be seen on or near the surface, and might have an off-and-on atmosphere that contains water vapor.
The scientists say all this and more in six research papers published in this week’s issue of the journal Science. The studies are based on more than a year’s worth of orbital observations from NASA’s Dawn spacecraft. Dawn is still circling 590-mile-wide Ceres, which is the solar system’s smallest dwarf planet as well as its biggest main-belt asteroid.
The mysterious mountain is Ahuna Mons, a 3-mile-high peak that looks like a bright space pyramid. Scientists took note of the peak’s concave top, its elliptical base, cracks at the summit, steep slopes and other features that pointed to previous volcanic activity.