Ceres classified as Dwarf planet, has icy surface

Dwarf Planet Ceres May Have Underground Ice, Scientists Say

In March of 2015, NASA's Dawn mission will arrive at the dwarf planet Ceres, the first of the smaller class of planets to be discovered and the closest to Earth.

The dwarf planet Ceres, which orbits the sun in the asteroid belt between Mars and Jupiter, is a unique body in the solar system, bearing many similarities to Jupiter's moon Europa and Saturn's moon Enceladus, both considered to be potential sources for harboring life.

On Thursday, August 15, Britney Schmidt, science team liaison for the Dawn Mission, and Julie Castillo-Rogez, planetary scientist from JPL, spoke in an Google Plus Hangout titled 'Ceres: Icy World Revealed?' about the growing excitement related to the innermost icy body. [Dwarf Planets of Our Solar System (Infographic)]

"I think of Ceres actually as a game changer in the solar system," Schmidt said.

"Ceres is arguably the only one of its kind."

The dwarf planet Ceres as seen by the Hubble Space Telescope.

The innermost icy body

When Ceres was discovered in 1801, astronomers first classified it as a planet. The massive body traveled between Mars and Jupiter, where scientists had mathematically predicted a planet should lie. Further observations revealed that a number of small bodies littered the region, and Ceres was downgraded to just another asteroid within the asteroid belt. It wasn't until Pluto was classified as a dwarf planet in 2006 that Ceres was upgraded to the same level.

Ceres is the most massive body in the asteroid belt, and larger than some of the icy moons scientists consider ideal for hosting life. It is twice the size of Enceladus, Saturn's geyser-spouting moon that may hide liquid water beneath its surface.

Unlike other asteroids, the Texas-sized Ceres has a perfectly rounded shape that hints toward its origins.

"The fact that Ceres is so round tells us that it almost certainly had to form in the early solar system," Schmidt said. She explained that a later formation would have created a less rounded shape.

The shape of the dwarf planet, combined with its size and total mass, reveal a body of incredibly low density.

"Underneath this dusty, dirty, clay-type surface, we think that Ceres might be icy," Schmidt said. "It could potentially have had an ocean at one point in its history."

"The difference between Ceres and other icy bodies [in the solar system] is that it's the closest to the sun," Castillo-Rogez said.

Less than three times as far as Earth from the sun, Ceres is close enough to feel the warmth of the star, allowing ice to melt and reform.

Investigating the interior of the dwarf planet could provide insight into the early solar system, especially locations where water and other volatiles might have existed.

"Ceres is like the gatekeeper to the history of water in the middle solar system," Schmidt said.