Astronomers have confirmed the presence of water on the dwarf planet Ceres, finding it in the form of massive plumes of vapor shooting from its surface. Orbiting at 2.8 astronomical units in a region called the asteroid belt, Ceres appears to be shooting off clouds of water vapor that may be the product of sublimation (water going directly from ice to vapor) or possibly the discharge of ice volcanoes on the planet’s frozen surface. This discovery represents the first definitive evidence of water on not just this dwarf planet, but on any object in the asteroid belt.
Suspicions of water on the Ceres dwarf planet (also referred to as a giant asteroid) have circulated for 30 years or so. A 1991 study found evidence of water in the form of hydroxide but was not able to confirm these findings with subsequent studies. It was not until this most recent study that Michael Kuppers and his team at the European Space Agency were able to officially confirm these suspicions. “This is the first clear-cut detection of water on Ceres and in the asteroid belt in general,” said Kuppers.
Using the Hershel Space Observatory, scientists discovered that Ceres was emitting water vapor from two specific points along its surface. They suspect that the vapor is escaping into the immediate atmosphere by sublimation or through cryovolcanos. Cryovolcanos are volcanos that emit volatiles (substances with low boiling points like water, ammonia, or beef stew) instead of molten rock. Completely ignoring how much cooler volcanoes are than sublimation, Kuppers himself said he considers the sublimation theory far more likely, Kupper notes that it would be “difficult to maintain the internal heat over the age of the solar system to maintain volcanoes.” More research will be necessary to confirm which phenomenon is the source of the vapor plumes, so volcano enthusiasts like me can go right on believing.
It won’t be long before we know even more about Ceres as NASA’s Dawn spacecraft is set to orbit the dwarf planet in 2015.
The iced surface of Ceres is something of an unexpected discovery considering its specific position in our solar system. There is a border in our solar system called the “snowline” which divides the drier interior from the region of icy objects (such as comets) farther out. Being on the inside of this borderline, the icy surface of Ceres suggests that more mixing has occurred than previously thought between these two distinct regions.
“One of the most puzzling questions about the evolution of asteroids”, said astrophysicists Humberto Campins and Christine Comfort, “is why Vesta and Ceres are so different.” Vesta is a slightly smaller dwarf planet in the same asteroid belt as Ceres that was found to have an igneous surface, the product of the molten rock volcanoes you and I are more familiar with. One possible explanation behind this discrepancy may have to do with Ceres’ water. Since water vapor can transport a great deal of heat, Ceres may have lost much of its heat as it expelled more and more vapor into space.
The discovery of water on Ceres supports a model of our solar system in which massive planets like Jupiter actually migrated to their present locations and that they consist of mixed materials from various regions of our solar system. Ice on Ceres also may support the notion that water was originally delivered to our planet (Earth) by an asteroid long ago. All in all, the confirmation of Ceres’ icy nature is a huge step forward in understanding our solar system and is great news for the dwarf planet’s pending bid to host the upcoming 3218 Winter Olympics.