Water, salt or an alien city? Scientists have been wondering about the strange bright spots on dwarf planet Ceres since NASA's in March, and now a new study in the journal Nature has put the spotlight on these light spots.

According to NASA,dot the dwarf planet. The glowing spots are found in Ceres' 60-mile-wide Occator crater, and new false-color images have enabled researchers to identify the nature of these blotches: They are consistent with a type of magnesium sulfate called hexahydrite.

A false color representation of Ceres' Occator Crater has given scientists new clues about the bright spots on this dwarf planet. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

"What we found is if we had very oblique views –if Ceres was located between the Sun and the spacecraft –there was an additional brightness on top of the general brightness of the bright spots," the study's lead researcher Andreas Natheus of the Max Planck Institute in Germany . "This brightness exists only during the daytime, like haze on Earth. This was a surprise."

The researchers think the salt deposits are remnants from a time when the dwarf planet was covered in water-ice, and there may be a layer of briny water-ice beneath the surface as well as a hazy layer of water-ice particles near the surface.

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"Ceres is the first identified large body in the main asteroid belt showing now only primitive Solar System material, but ," the researchers said in the study.

A second study published in Nature gives yet more clues about Ceres, this time about the dwarf planet's origin. The research, conducted by a separate team at the National Institute for Astrophysics in Rome, found unexpected ammonia-rich clays on the Ceres' surface.

"Ammonia ice by itself would evaporate on Ceres today, because the dwarf planet is too warm," NASA's Jet Propulsion Laboratory . "However, ammonia molecules could be stable if present in combination with (i.e. chemically bonded to) other minerals."

This would mean that Ceres could have , says lead author Maria Cristina De Sanctis, or it could have gathered materials from the outer solar system that floated into the asteroid belt.

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