Don't know yet

Here's a link to a discussion of what the Dawn satellite, circling the asteroid Ceres, learned and what it's going to do next.

Dawn Journal, June 29

A couple of crumbs to follow:

"And what marvels Dawn has beheld! How can you not be mesmerized by the luminous allure of the famous bright spots? They are not, in fact, a source of light, but for a reason that remains elusive, the ground there reflects much more sunlight than elsewhere. Still, it is easy to imagine them as radiating a light all their own, summoning space travelers from afar, beckoning the curious and the bold to venture closer in return for an attractive reward."

And:

"In addition to evidence of aging and renewal, some powerful internal forces have uplifted mountains. One particularly striking structure is a steep cone that juts three miles (five kilometers) high in an otherwise relatively smooth area, looking to an untrained (but transfixed) eye like a volcanic cone, a familiar sight on your home planet (or, at least, on mine). No other isolated, prominent protuberance has been spotted on Ceres."

Much more to learn. But now Dawn takes a break and lets the New Horizons Pluto flyby take the spotlight.