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Published:February 2nd, 2014 13:40 EST
Deep-Space Discovery: Dwarf Planet Ceres

Deep-Space Discovery: Dwarf Planet Ceres

By Derek Sanders

A dwarf planet is a planetary mass whose size makes it bigger than an asteroid but smaller than a planet. As a dwarf planet with a diameter of 950 km, Ceres is the largest object in the asteroid belt between Mars and Jupiter. Many people first learned about dwarf planets when Pluto was declared as one in 2006, after decades of children were taught that it was a full-sized planet. Ceres was reclassified after decades of being known as the largest asteroid in the solar system. A recent discovery however, has Ceres receiving more attention from the scientific community.

A group of scientists using the European Space Agency`s Herschel space observatory between 2011 and 2013 have found that Ceres is surrounded by a thin atmosphere of water vapor. Using Herschel`s far-infrared vision, they determined that the dwarf planet has a spectral signature of water vapor surrounding it. The research was conducted as a part of the ESA`s MACH-11 program, or Measurements of 11 Asteroids and Comets Using Herschel, where they use Herschel to observe small bodies in space that have been or will be visited by spacecraft.

Such an idea was theorized but until now, it received no incontestable conclusion. They believe that the former asteroid is layered with a rocky core and a thick outer mantle of ice that, if melted, would amount to more fresh water than is present on Earth. When Ceres reaches the part of its orbit that is closer to the sun, a portion of its icy surface warms, allowing the vapor to shoot up into its atmosphere.

"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, a member of the ESA in Spain and the lead author of a paper in the journal Nature.

This information was found just as NASA`s Dawn mission is beginning to make its way to Ceres after orbiting the asteroid Vesta for more than a year. The spacecraft will land on Ceres in the spring of 2015, when NASA scientists will be able to use it to gather more data about the planetary body.

"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 in Pasadena, CA. "Dawn will map the geology and chemistry of the surface in high-resolution, revealing the processes that drive the outgassing activity."

The results from these observations are receiving so much attention because comets are typically known to show jets and plumes of water vapor while asteroids and dwarf planets are not. The fact that Ceres is undergoing such behavior has scientists wanting to find out why this is the exception, with them stating that this is their first detection of such a phenomenon occurring in an asteroid like object.

Herschel`s discovery of water vapor outgassing from Ceres gives us new information on how water is distributed in the Solar System. Since Ceres constitutes about one fifth of the total mass of the asteroid belt, this finding is important not only for the study of small Solar System bodies in general, but also for learning more about the origin of water on Earth, " says Göran Pilbratt, ESA`s Herschel Project Scientist.

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