The Dawn spacecraft reveals their true nature
We’ve all heard about Pluto being a dwarf planet, but there are many less famous objects in the same category. Ceres, the closest dwarf planet to the sun, is located in the asteroid belt between Mars and Jupiter, and something about it has been puzzling scientists.
NASA scientists first noticed 130 bright spots on the dwarf planet’s surface when they were observing it earlier this year. As will tend to happen, there were speculations that the spots were caused by extraterrestrial life. Thanks to the Dawn spacecraft, which is currently orbiting Ceres, we know that there is a perfectly reasonable scientific explanation.
In a paper published in Nature, researchers from the Max Planck Institute for Solar System Research report that the brightness is due hexahydrite, a type of magnesium sulfate similar to Epsom salt. Although it doesn’t technically shine, it reflects sunlight. The spots likely formed as ice sublimated due to asteroid strikes.
However, researchers express caution in rushing to any conclusions: “Because of the lack of diagnostic spectral features in many candidate minerals, we stress that we cannot rule out other materials or processes.” "For sure we will get better insights into the processes," Nathues told Space.com in reference to new data that will come in as Dawn continues its work.
The Dawn spacecraft has been orbiting Ceres since March 6, 2015. Before that, it orbited Vesta, a protoplanet, for 14 months. It is the first mission of it’s kind where a probe is sent to visit a dwarf planet and orbit two distinct solar system targets. Over the next two months, Dawn is mapping the dwarf planet six times and using its visible and infrared mapping spectrometer to collect data about the minerals found on Ceres’ surface.