New research features Ceres’ bright spots. According to New Scientist:
“These spots are telling a story of a younger, more geologically active Ceres than researchers expected. That’s because we would expect material ejected by impacts to mix eventually and create a uniform surface.”
The most logical explanation is that there hasn’t been enough time.
McKinnon, Mika. 2017. The mysterious bright spots on Ceres may have a common origin. New Scientist (2 October).