Image copyright NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The fascinating bright spots on the surface of the dwarf planet Ceres have come into sharper view.

What were initially thought to be just a couple of brilliant, closely spaced features at one location now turn out to be a clutch of many smaller dots.

The latest pictures were acquired by the US space agency's Dawn spacecraft on its first full science orbit since arriving at Ceres on 6 March.

The spots were seen from a distance of 13,600km.

Researchers on the mission concede they still have much to learn about the dots' true nature, but the new data is hardening their ideas.

"Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice," said Chris Russell, who is the principal investigator on the mission.

With a diameter of 950km, Ceres is the largest object in the main asteroid belt between Mars and Jupiter.

Dawn will spend the coming months studying its geology and surface chemistry with a suite of cameras and remote-sensing instruments.

The intention is to get some insights into the processes that have sculpted the dwarf since its formation with the rest of the Solar System some 4.5 billion years year ago.

Having completed its first science orbit, Dawn is now heading downwards to get even closer to the body.

This second mapping campaign, which will commence on 6 June, will see Dawn moving just 4,400km from the surface.

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos