“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of the European Space Agency.
The scientists, writing in the journal Nature, believe the water vapor is produced on Ceres when its orbit brings it close enough to the sun to melt parts of its icy surface.
The water vapor, heated by the warmth of the sun, then blasts above the Dwarf planet in plumes at a rate of about 6 kilograms per second, according to the research team. The water vapor disappears whenever Ceres’ orbit takes it away from the sun.
Ceres is the largest and roundest object to inhabit the asteroid belt between the orbits of Mars and Jupiter.
Ceres is about 950 kilometers in diameter, has a rocky interior and is coated with a thick layer of ice. Scientists believe the dwarf planet has so much ice that if it were all melted, it would produce more fresh water than is available on Earth.
Up until 2006, Ceres was classified as a large asteroid, but then the International Astronomical Union (IAU), which is responsible for naming planetary objects, reclassified it as a dwarf planet because of its large size.
Along with Ceres, the IAU currently lists four other dwarf planets in our solar system. They are Pluto (formerly a full-fledged planet), Eris, Makemake and Haumea, all of which orbit the sun beyond Neptune. Of the five, Ceres is the only dwarf planet known to exist in the asteroid belt.
While it’s been previously thought that ice existed on Ceres, it wasn’t until scientists using tools such as the Herschel space telescope‘s Heterodyne Instrument for the Far-Infrared (HIFI) were able to spot a clear spectral signature of water vapor.
Comets, the icy relatives of asteroids, have been known to blast jets and plumes of gas and vapor, but the scientists were surprised to observe similar behavior on an object that resides in the asteroid belt.
Scientists will get a closer look at Ceres when NASA’s Dawn mission arrives for a scheduled visit during the spring of 2015. Dawn is on its way to Ceres after spending more than a year orbiting the large asteroid Vesta.
“We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself,” said Carol Raymond, NASA’s deputy principal investigator for Dawn. “Dawn will map the geology and chemistry of the surface in high-resolution, revealing the processes that drive the outgassing activity.”