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BREAKING! the bright spots on Ceres are CHANGING!! Scientists baffled as to why!!!
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Observations made using the HARPS spectrograph at ESO’s La Silla Observatory in Chile have revealed unexpected changes in the bright spots on the dwarf planet Ceres. Although Ceres appears as little more than a point of light from the Earth, very careful study of its light shows not only the changes expected as Ceres rotates, but also that the spots brighten during the day and also show other variations.
These observations suggest that the material of the spots is volatile and evaporates in the warm glow of sunlight.
The most prominent of these spots lie inside the crater Occator and suggest that Ceres may be a much more active world than most of its asteroid neighbours.
New and very precise observations using the HARPS spectrograph at the ESO 3.6-meter telescope at La Silla, Chile, have now not only detected the motion of the spots due to the rotation of Ceres about its axis, but also found unexpected additional variations suggesting that the material of the spots is volatile and evaporates in sunlight.
The lead author of the new study, Paolo Molaro, at the INAF–Trieste Astronomical Observatory, takes up the story: "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. As Ceres rotates the spots approach the Earth and then recede again, which affects the spectrum of the reflected sunlight arriving at Earth.”
Ceres spins every nine hours and calculations showed that the effects due to the motion of the spots towards and away from the Earth caused by this rotation would be very small, of order 20 kilometers per hour. But this motion is big enough to be measurable via the Doppler effect with high-precision instruments such as HARPS.
The team observed Ceres with HARPS for a little over two nights in July and August 2015. "The result was a surprise," adds Antonino Lanza, at the INAF–Catania Astrophysical Observatory and co-author 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.”
The team concluded that the observed changes could be due to the presence of volatile substances that evaporate under the action of solar radiation. When the spots inside the Occator crater are on the side illuminated by the Sun they form plumes that reflect sunlight very effectively. These plumes then evaporate quickly, lose reflectivity and produce the observed changes. This effect, however, changes from night to night, giving rise to additional random patterns, on both short and longer timescales.
[link to www.astrowatch.net]
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