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The Dawn spacecraft flew about 1470 kilometers from Ceres when it took this picture of the Haulani Crater. The bluish tones in the color image suggest that the 34 kilometer impact is still quite young. (Photo: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA)

Die Raumsonde Dawn flog circa 1470 Kilometer entfernt von Ceres, als sie dieses Bild vom Haulani-Krater machte. Die bläulichen Töne in der Farbaufnahme lassen darauf schließen, dass der 34 Kilometer messende Einschlag noch recht jung ist. (Foto: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

The Dawn spacecraft flew about 1470 kilometers from Ceres when it took this picture of the Haulani Crater. The bluish tones in the color image suggest that the 34 kilometer impact is still quite young. (Photo: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA)

The dwarf planet Ceres is under close observation of NASA. At the beginning of March 2015, the spacecraft Dawn entered the orbit of the largest planetoid in our solar system and has since been delivering images of the surface of the black sphere. Astronomers want to use the images to find out what the celestial body is like inside. Because Ceres could reveal a lot about the early phase of our solar system. Unlike numerous space debris, it was not captured by the nascent planets. Important indications of the quality of Ceres are the approximately 130 white spots on its surface.

Ceres measures 950 kilometers in diameter. The dwarf planet moves in the planetoid belt between Mars and Jupiter, but could have originally drifted from the edge of our solar system into the debris field. Researchers conclude from the images that NASA made using the space probe Dawn. The pictures also show another peculiarity of the planetoid: around 130 white, bright spots. In addition, the Herschel space telescope was able to detect water vapor on the surface as early as 2014, rising above the patches in clouds of fog.

Andreas Nathues from the Max Planck Institute for Solar System Research in Göttingen and his colleagues have long been searching for an explanation for the patches and swells of steam. Their latest result, based on Dawn's light spectral data and photos: Under the crust is water ice, which has a high salt content. Because this frosty mixture could liquefy even at maximum temperatures of minus 90 degrees, which prevail around Ceres. In addition, the haze always rises when sunlight hits a white crater floor. This strongly reminds the researchers of the outgassing of comets and might suggest that planetoids and comets are not dissimilar.

Cracked surface

When haze rises, white spots remain. Also from the spectral data close Nathues and his team that they consist of magnesium sulphates - some of them are hydrogen-containing, others are dry. Most of the spots are in craters. This also gave the researchers an indication of how the water ice could make its way to the surface. The astronomers suspect that meteorite impacts have cracked the otherwise hard surface of Ceres: The salt-water ice mixture escapes, the water evaporates, and the salt deposits as white patches on the surface.

From the light spectral data, researchers also concluded that abundant ammonium is present on Ceres. They further suggest that it formed from a reaction with ammonia ice vor a long time ago, when perhaps Ceres was not floating in the planetoid orbit between Mars and Jupiter, but on the edge of our solar system. Ammonia ice is only present at very cold temperatures, such as those prevailing near Neptune. Ceres could therefore contain information about how our solar system once was. display

To Ceres you read also in picture of the science 3/16, "dwarf planet Ceres very close".

A virtual flight over the dwarf planet Ceres (Video: DLR)

Science.de - Karin Schlott
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