Dwarf Planet Ceres Shooting Plumes of Water Vapor Between Mars and Jupiter

Astronomers have confirmed the presence of water vapor on Ceres, the dwarf planet in the asteroid belt between Mars and Jupiter.

Water vapor was detected on Ceres by the Herschel space observatory, which is a project of the European Space Agency (ESA). A report covering the water vapor-detection process is published in the journal Nature.

At one time Ceres was considered the largest asteroid in the solar system, but now it is one of five dwarf planets in our solar system currently recognized by the International Astronomical Union (IAU), although there are likely hundreds more.

The most well-known of the dwarf planets is Pluto, which was demoted from its status as a true planet in 2006 after the IAU formally laid down criteria for what defines a planet, at the same time creating a new category of celestial body known as a dwarf planet.

As Pluto was demoted, Ceres, which was first discovered in 1801, was reclassified from a gigantic asteroid to a dwarf planet.

"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 lead study author Michael Küppers of ESA in Spain.

Küppers and his colleagues observed two plumes of vapor emanating sporadically from Ceres. What is triggering the water vapor plumes remains a mystery, but NASA's Dawn mission scheduled to arrive at Ceres early next year should reveal some answers.

"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, the deputy principal investigator for Dawn at NASA's Jet Propulsion Laboratory. "Dawn will map the geology and chemistry of the surface in high resolution, revealing the processes that drive the outgassing activity."

Humberto Campins, a planetary scientist at the University of Central Florida in Orlando, told the Nature news blog that it was fascinating that the vapor pluming was only detected in two areas.

He speculated that the source could be a pair of cryovolcanoes, which erupt volatiles such as water, ammonia or methane instead of lava. Another possibility is that the water vapor plumes have their origin at an unusually rich source of water ice within Ceres.

"We don't have enough information to discriminate at this point," Campins told Nature, adding that the source must somehow be continuously replenished, regardless of what it is.

"Scientists believe Ceres contains rock in its interior with a thick mantle of ice that, if melted, would amount to more fresh water than is present on all of Earth," NASA said in a statement. "The materials making up Ceres likely date from the first few million years of our solar system's existence and accumulated before the planets formed."

NASA's Dawn probe, which was launched in 2007, will be at Ceres in early 2015.

Christopher Russell, a planetary scientist at the University of California, Los Angeles told Nature he was confident that the Dawn mission will answer many unanswered questions about Ceres.

"Once we get there, we'll figure out where [the water] is getting out, and how," Russell said.