Ceres continues to baffle astronomers as the Dawn spacecraft gets closer to being captured into orbit around the dwarf planet.
While Nasa has not provided an explanation, scientists suggest these spots may be frozen pools of ice at the bottom of a crater that reflect light.
‘Right now, all we can say is that the material reflects 40 per cent or more of the light falling on it,’ UCLA astronomer Chris Russell, the principal investigator for the Dawn mission, told NBC News.
‘This limit is because of the resolution of the camera at this distance from Ceres. If the final answer is that it reflects all the light that falls on it, then the most probable reflector would be ice.’
He added that there may be a volcano-like origin of the spots, but that Nasa will have to wait for better resolution before we can make such geologic interpretations.
Using its ion propulsion system, Dawn will enter orbit around Ceres on March 6.
When it does, it will become the first human-made probe to visit the ‘Death Star’ planet – and scientists hope it will uncover the secrets behind its mysterious white spot.
As scientists receive better and better views of the dwarf planet over the next 16 months, they hope to gain a deeper understanding of its origin and evolution by studying its surface.
The intriguing bright spots and other interesting features of this captivating world will come into sharper focus.
‘The brightest spot continues to be too small to resolve with our camera, but despite its size it is brighter than anything else on Ceres,’ said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research, Gottingen, Germany.
Earlier this month, Dawn returned yet another series of stunning animations of Ceres as its moves ever closer to the dwarf planet.
At a resolution of 8.5 miles (14km) per pixel, the pictures represent the sharpest images to date of the icy world, which Dawn is due to arrive at on March 6.
The set of images – which are stitched together in an animation – were taken on February 4th at a distance of about 90,000 miles (145,000 km).
‘We know so little about our vast solar system, but thanks to economical missions like Dawn, those mysteries are being solved,’ said Jim Green, Planetary Science Division Director at Nasa.
Over the next weeks, Dawn will provide increasingly sharper images of the icy world.
‘We know so much about the solar system and yet so little about dwarf planet Ceres.
‘Now, Dawn is ready to change that,’ said Marc Rayman, Dawn’s chief engineer and mission director, based at Nasa’s Jet Propulsion Laboratory in California.
Ceres is 590 miles (950 km) across and was discovered in 1801. In January, researchers discovered that water was gushing from its surface at a rate of 13lb (6kg) per second.
‘Now, finally, we have a spacecraft on the verge of unveiling this mysterious, alien world,’ Dawn mission director and chief engineer Marc Rayman, of Nasa’s Jet Propulsion Laboratory in Pasadena, California said.
‘Soon it will reveal myriad secrets Ceres has held since the dawn of the solar system.’
Observations by the European Space Agency’s Herschel telescope suggested they could be coming from geysers or ice volcanoes.
Ceres orbits the sun in the asteroid belt between Mars and Jupiter and is very similar to Jupiter’s moon Europa and Saturn’s moon Enceladus – both considered potential sources for harbouring life.