More than 10 years after the Hubble Space telescope captured bright white spots on the dwarf planet Ceres, the Dawn probe is ready to get to the bottom of the mystery — just not quite yet. The latest photos from Dawn, taken on Feb. 12 at a distance of 52,000 miles from the cratered surface of Ceres, show the white areas in greater detail than ever before, but it's not enough for scientists to identify their cause.
Are they chalky mountains? Surface encrusted with ice from water vents? Frozen crater-bound lakes?
"We expected to be surprised; we did not expect to be this puzzled," said Dawn's principal investigator, Chris Russell, in a JPL press release accompanying the latest pictures.
This sense of wonderment can't last long: Dawn is scheduled to enter orbit around Ceres (the 590-mile-wide dwarf planet located in the asteroid belt between the orbits of Mars and Jupiter) in just a few weeks, and progressively closer imagery may reveal the secret of the spots even before then. Until that time, however, it is an exciting and rare situation to have a mystery of planetary proportions lying in our own cosmic back yard.