Science & Environment

Ceres' bright spots back in view

Ceres Image copyright NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Image caption The twin spots in "Region 5" have been the big talking point so far

The mysterious bright spots on the dwarf planet Ceres are back in view.

Nasa's Dawn spacecraft, which arrived at the mini-world on 6 March, is now settling into its first science orbit some 13,500km above the surface.

The probe's approach took it around the back of the dwarf and on to the night side, hiding the spots from the camera system and remote sensing instruments.

But with each passing day, Dawn is seeing more sun-lit terrain - including now its most enigmatic features.

The newly released sequence of images were acquired a week ago when the probe was still some 22,000km from the surface.

Nonetheless, they clearly show the brightest spot and its companion standing out against the darker landscape.

The science team on the US space agency mission do not yet have a name for the location, referring to it simply still as Region, or spot, 5.

Quite why the spots should reflect sunlight so efficiently in comparison to their surroundings is uncertain. It hints at the presence of ice - but ice would not be stable on an airless body. Another suggestion is salts, perhaps left behind after exposed ices had vaporised.

What is intriguing is that not all bright spots on Ceres are the same in nature. Another spot location, known as region 1, is very much cooler than the terrain that surrounds it. Region 5 displays no such behaviour.

Chris Russell, the principal investigator on Dawn, told BBC News last week: "It may be a surface composition situation in that the different material at that particular spot conducts heat differently than in the other area. So, the first thing you go to when you see different temperatures is the different thermal conductivity of the surface material."

Dawn will conduct an intense observational campaign starting this week, with the data being downlinked in early May. Scientists should then have something more definitive to say about Ceres and its enthralling spots.

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

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