Ceres' Bright Spots Just Became Even More Mysterious

Wednesday, 16 March 2016 - 10:48AM
Astronomy
Solar System
Wednesday, 16 March 2016 - 10:48AM
Ceres' Bright Spots Just Became Even More Mysterious
The long-running mystery of Ceres' white spots may have been virtually solved late last year, but there's still plenty we don't know about these strange geologic features. According to new ground-based observations, the white spots are still something of a wildcard, as they've been shown to change throughout the course of the day.

Ceres' white spots first came to astronomers' attention when they appeared in pictures taken by the Dawn spacecraft in early 2015, and because scientists had no idea what they were, they became the subject of intense speculation. The prevailing explanation was deposits of water ice for a time, but in December, scientists discovered that the white spots most likely consist of salt deposits, hydrated magnesium sulfate to be exact, with some water ice scattered throughout. 

But even though we now know what those bright deposits are, a new study shows that the mystery is far from over. When researchers measured the light reflecting off of Ceres' bright spots at different times, they found that the spots brighten and darken over the course of the day. This not only confirms previous reports of time-dependent haze over the Occator and Oxo craters, but also shows that we may not know as much about the deposits' composition as we thought. 

According to the researchers from the recent study, the most likely explanation for this variability is the sublimation of volatile substances within the bright spots. When the sun shines on the bright spots, the sublimation process produces a transient haze that causes the spots to seem brighter. Then, at night, the spots grow dimmer when the haze clouds evaporate.

If this is the case, then Ceres must be continually producing substances, in order for material to continue to leak from the system. As a result, Ceres may be much more geologically active than scientists originally believed.

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"This implies a leakage from the interior and therefore a source of internal heating, which is not easy to find for an isolated body," study author Paulo Molaro told Gizmodo.
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