Ceres is Cloudy, with a Chance of Cryovolcanoes

Astrogeology, Asteroids, Robots, Space Flight & Extraterrestrial Matters

Date posted: 12/11/15

Lee Billings reports that even a dwarf planet can harbor big surprises. Ever since it was discovered floating between Mars and Jupiter in 1801, Ceres has perplexed astronomers and defied easy categorization. Telescopic studies over the years showed it was roughly the size of Texas, with up to a third of its weight in water ... too small to be a true planet, too wet and icy to be an asteroid and too big and rocky to be a comet. Astronomers chalked up the Ceres oddities to its being a relic from an early, formative epoch of our solar system, when planets coalesced from many Ceres-like objects moving around the sun. For lack of any better ideas, they also chose to include Ceres in the dwarf planet category they created for Pluto in 2006. Now, new results from the NASA Dawn spacecraft, which has been orbiting Ceres since March, hint that the body may have much more in common with its diminutive dwarf-planet cousin Pluto than once thought. Dawn co-investigator Maria Cristina De Sanctis of the National Institute of Astrophysics in Rome, Italy and colleagues report their detection of abundant ammonia-rich minerals on the Ceres surface, suggesting that it was born closer to the vicinity of Pluto even though it now orbits in the Asteroid Belt. Separately, a team led by Andreas Nathues of the Max Planck Institute for Solar System Research in Germany, has found what appears to be cloud-like hazes of water vapor emanating from one of the mysterious bright spots that dot Ceres asphalt-dark surface. In keeping with all the rest of the Ceres oddball uncertainties, the findings hold major, albeit nebulous implications for our understanding of the dwarf planet and its relationship to the other large objects in our solar system. Many theorists now believe that in our solar system infancy its giant planets shifted over hundreds of millions of kilometers, propelled by gravitational interactions between the planets and orbiting disks of debris, which may have forced Ceres inward.