Ceres' bright spots continue to baffle scientists, who once thought they had them figured out, because they keep changing from when NASA's Dawn spacecraft took its first close-up pictures of the dwarf planet last year.
Ceres, the largest body in the asteroid belt between Mars and Jupiter and officially classified as a dwarf planet like Pluto, fascinated researchers with its bright spots that they believed to be made of hydrated magnesium sulfates, noted
Space.com.
However, a
European Southern Observatory release said recent examinations have shown that the spots are changing unexpectedly, brightening during the day. The observatory said the changes suggest that the spots may be volatile and evaporates in the sunlight.
"As soon as the Dawn spacecraft revealed the mysterious bright spots on the surface of Ceres, I immediately thought of the possible measurable effects from Earth," said Paolo Molaro, the lead author of the new study. "As Ceres rotates the spots approach the Earth and then recedes again, which affects the spectrum of the reflected sunlight arriving at Earth."
Space.com said Ceres had been studied by the Hubble Space Telescope before Dawn took its close-up shots in 2015 but the dwarf planet was too small to detail its landscape. Hubble, though, did notice then variations on Ceres' surface, which turned out to be the bright spots.
According to the observatory, when the spots inside Ceres' Occator crater are on the side illuminated by the Sun, they form plumes that reflect sunlight. The plumes then evaporate quickly, lose reflectivity and produce changes, noted the observatory.
"The result was a surprise," said Antonino Lanza, a coauthor of the study. "We did find the expected changes to the spectrum from the rotation of Ceres, but with considerable other variations from night to night."
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