Regions of higher than average albedo (reflectiveness) have been long known to exist on Ceres, but the low resolution of the observations have prevented planetary scientists from interpreting what they could be. But with the slow arrival of Dawn, these bright spots turn out to be discrete locations that might indicate surface ice features - possibly evidence for cryo-volcanism.
ANALYSIS: Craters Pop as NASA's Dawn Probe Approaches Ceres
Cryovolcanoes can form on cold bodies in the solar system, such as the moons orbiting Jupiter and Saturn or dwarf planets in the Kuiper belt, but rather than molten rock being ejected to the surface (such is the case for regular volcanoes on Earth), liquid water, methane or ammonia may be forced to the surface after undergoing some heating through radioactive or tidal processes. Once vented, these cryovolcanoes may leave frozen residue on the surface, possibly resembling what we are beginning to see on Ceres. But until we get closer, any positive identification will remain elusive for the time being.
"The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres," said Andreas Nathues, of the Max Planck Institute for Solar System Research in Gottingen, Germany, and lead investigator for Dawn's framing camera team. "This is truly unexpected and still a mystery to us."
NEWS: What is That Mysterious White Blob on Ceres?
Having already visited massive asteroid Vesta from 2011 to 2012, Dawn is slowly approaching its second asteroid belt target where it will continue to explore for the next 16 months. Soon after, its thruster fuel will run dry and it will remain, stuck in orbit around Ceres as a permanent artificial satellite of the dwarf planet. Before this happens, however, Dawn will transform our view of Ceres, providing us with invaluable and historic knowledge of the solar system's innermost dwarf planet.