Dwarf planet Ceres may have more fresh water than Earth

Astronomers using the Herschel Space Observatory have made the first definitive detection of a thin water-vapour atmosphere surrounding the dwarf planet Ceres, and if their estimations are correct, there may be more fresh water there than we have here on Earth!

For the past few years, scientists have been taking a careful look at Ceres, the dwarf planet that orbits the sun between Mars and Jupiter, in our solar system's asteroid belt. Given its size and shape — nearly 500 kilometres across and the roundest object in the asteroid belt — there's been speculation that Ceres may be similar to other bodies, like Jupiter's Europa and Saturn's Enceladus, with a rocky core surrounded by a thick mantle of ice. However, while there have been clues about the possibility of water ice there, and even that Ceres had an atmosphere, there hadn't yet been any solid evidence.

Now, by using Herschel's infrared cameras, astronomers have spotted plumes of water vapour from the surface of Ceres, confirming the speculations about the dwarf planet's composition.

"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, the study lead author, according to NASA.

The plumes they spotted weren't constant, though. Since Ceres' orbit brings it significantly closer to the sun at some times, the plumes were more prominent then, and they stopped when it was farther away. The plumes also varied in strength over hours and days as well, and careful observation allowed the scientists to track them to dark patches on Ceres' surface. These would obviously absorb more sunlight than the bright areas around them, so there would be more melting at those spots, and the variation was caused by these spots rotating towards the sun and then away from the sun as Ceres spun on its axis.

According to the NASA press release, scientists estimate that if the ice from Ceres was melted completely, there would be more fresh water on the dwarf planet than we have here on Earth (we may have a lot of water here, but only 2.5 per cent of it is actually fresh water).

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It's not known yet if the water vapour plumes on Ceres are caused simply by ice evaporating, like we see from comets, or if this is an example of cryo-volcanism (volcanoes that shoot out water and ice instead of magma). However, with NASA's Dawn mission arriving there in spring of 2015, we could have the answer very soon.

"We've got a spacecraft on the way to Ceres," said Carol Raymond, the Dawn mission's deputy principle investigator, according to NASA, "so we don't have to wait long before getting more context on this intriguing result, right from the source itself."

(Images courtesy: ESA/ATG medialab, Wikipedia)

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