This from Alexandra Witze from NATURE:
Not all of the puzzling bright spots on the dwarf planet Ceres are alike. The closest-yet images of the gleams, taken from 45,000 kilometres away, suggest that at least two of the spots look different from one another when seen in infrared wavelengths.
The Hubble Space Telescope spied many of the bright spots from afar years ago, but the observations from NASA's Dawn spacecraft — which began looping around Ceres on 6 March — are the first at close range. The images were released on 13 April in Vienna, Austria, at a meeting of the European Geosciences Union.
Scientists say that the bright spots may be related to ice exposed at the bottom of impact craters or from some kind of active geology. They glimmer tantalizingly in a new full-colour map of Ceres, obtained in February but released at the conference. The map uses false colours to tease out slight differences on the otherwise dark surface of Ceres.
Spot 1 appears darker in images from Dawn's infrared spectrometer, said Federico Tosi, a Dawn scientist at the Institute for Space Astrophysics and Planetology and the Italian National Institute for Astrophysics in Rome. That suggests that the area is cooler than the rest of the dwarf planet's surface, supporting the idea that the spot is made of ice.
But for some reason Spot 5 — the brightest feature seen on Dawn — does not show up in infrared images. “One possibility is that we still don’t have enough resolution to see it in the proper way,” said Tosi.
And some truly fun theories exist about these bright spots on Ceres..