NASA’s Dawn spacecraft has beamed back a new photo of a cluster of bright spots on the surface of the dwarf planet Ceres. The space probe took this image at an altitude of 2,700 miles (4,400 km).

Ceres’ bright spots consist of several smaller spots, with a central cluster. The region with the spots is in a crater about 55 miles (90 km) across.

So far, planetary researchers with the Dawn mission have found no conclusive explanation for their observed locations or brightness levels.

“The bright spots in this configuration make Ceres unique from anything we’ve seen before in the Solar System. The team is working to understand their source,” said Dawn principal investigator Dr Chris Russell of the University of California, Los Angeles.

“Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt.”

“With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon.”

Dawn deputy principal investigator Dr Carol Raymond of NASA’s Jet Propulsion Laboratory in Pasadena added: “the surface of Ceres has revealed many interesting and unique features. For example, icy moons in the outer solar system have craters with central pits, but on Ceres central pits in large craters are much more common.”

Dawn has been studying the dwarf planet in detail from its second mapping orbit, which is 2,700 miles (4,400 km) above Ceres.