For all the people who have been waiting anxiously for a definitive explanation for those mysterious bright spots on the dwarf planet Ceres, the latest word from NASA is good news for those with sore feet. No, it’s not lights directing aliens to the offices of a podiatrist who specializes in reptilian appendages. The answer from NASA is that the light is a reflection off of hydrated magnesium sulfates, which is a form of the compound better known on Earth as Epsom salt.
New photos of the infamous bright spot (located in what is now called the Occator Crater) and other areas taken by the Dawn spacecraft during a flyover from an altitude of 4,400 km (2,700 miles) were analyzed by a team from the Max Planck Institute for Solar System Research in Germany. Using a new exposure technique that better differentiated between the dark and light areas, the team found a total of 130 bright spots that were almost always in craters. From this they determined that whatever was causing the spots was brought to the surface by asteroid impacts.
What those asteroid impacts uncovered was identified by spectral analysis to be hydrated magnesium sulphates, which is the main ingredient in Epsom salt on Earth. This finally confirmed the popular theory that Ceres has a subsurface area made of briny water and ice.
While looking at the bright spots, the researchers found something else … ammonia-rich clays. This means that Ceres, which is located in the asteroid belt between Mars and Jupiter, probably came originally from an area loaded with ammonia and nitrogen, like the outer part of the solar system near the orbit of Neptune where nitrogen ice is abundant.
The combination of these two new findings, outlined in the current edition of the journal Nature, indicates that Ceres is not quite an asteroid and not quite a comet but something in between. More details on what this means could come later this month when Dawn, currently in its final orbit at 385 km (240 miles) takes pictures with a resolution of 35 meters (120 feet)
That resolution may be good enough to identify any aliens soaking their feet in a crater of Epsom salts.