Herschel boffins spot fat dwarf Ceres in TEARS over astro-identity crisis

Am I an asteroid? Am I a dwarf planet? JUST TELL ME, you heartless fiends!

Artist's impression of Ceres

As every chubby kid will know, it's no fun being bigger than all the other children in the playground.

So spare a thought for Ceres, the solar system's largest and roundest asteroid, which is so upset about being fat that it's crying watery tears way out in space.

Boffins used Europe's infrared Herschel space telescope to peer closely at the surface of Ceres, which is thought to contain a large amount of ice.

The space scientists noticed vapour coming from dark patches on the asteroid, but are not entirely sure what's causing these small plumes.

It could be that the Sun is heating up ice on the surface of Ceres, which then turns into a gas and disperses out into space. However, Michael Kuppers, of the European Space Agency, suggested a more exciting explanation.

"Another possibility is that there is still some energy in the interior of Ceres, and this energy would make the water vent out in a similar way as for geysers on Earth, only that with the low pressure at the surface of the asteroid, what comes out would be a vapour and not a liquid," he said.

We will find out for sure when NASA's Dawn probe reaches Ceres early next year.

Boffins are understandably excited about the chance of gawping at the solar system's most sizeable asteroid.

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

There's not a huge amount of liquid "outgassing" from Ceres, which is so hefty that it can be categorised as a dwarf planet. About six kilogrammes of fluid is thought be emitted each second, which might sound like a lot until you hear that scientists think Ceres contains more fresh water than the whole of planet Earth.

The latest results were unexpected because objects in the asteroid belt don't usually spew water, while comets often do.

"The lines are becoming more and more blurred between comets and asteroids," said Seungwon Lee who also work's at NASA's jet propulsion laboratory. "We knew before about main belt asteroids that show comet-like activity, but this is the first detection of water vapor in an asteroid-like object."

The findings were reported in the journal Nature. ®

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