Newly Discovered Exoplanet May Have Water Clouds
This artist's impression shows the transiting exoplanet Corot-9b, the first "normal" exoplanet that can be studied in great detail. This planet has the size of Jupiter and an orbit similar to that of Mercury. It orbits a star similar to the sun located 1500 light-years away from Earth towards the constellation of Serpens (the Snake). Like our own giant planets, Jupiter and Saturn, the planet is mostly made of hydrogen and helium.
Credit: ESO/L. Calçada

An alien planet recently found orbiting another star has the potential to host water in its atmosphere, scientists say.

The suspected temperate nature of the planet ? whose surface temperature is somewhere between minus 4 and plus 360 degrees Fahrenheit (minus 20 and plus 160 degrees Celsius) ? could mean that it it could have liquid water.

But this water wouldn't be in the form of Earth-like oceans, more likely it would be only in the form of clouds with water droplets, said Tristan Guillot, a member of the team that discovered the planet.

Astronomers announced the discovery of the planet, dubbed CoRoT-9b, last week, when they described it as a Jupiter-sized world that orbits its parent star at about the orbit of Mercury in our solar system.

This distance, while it seems close to the star, is considerably further out than many other known Jupiter-sized exoplanets, which means that CoRoT-9b likely escapes the wild temperature extremes experienced by those planets. [Weird Alien Planets Gallery]

Such an example of this can be seen in our own solar system, again on Jupiter.

"The same is true for Jupiter, which actually has water clouds, but they're hidden from view in the deep atmosphere," Guillot told SPACE.com in an e-mail.

Water oceans are out of the question because gas giant planets "don't have any surface: one goes continuously from the atmosphere to a progressively denser environment in the interior," Guillot said.

The interior of the planet would look something like this:

?"In the very deep interior, there may be a core made of water compressed to extremely high pressures (10 million times the atmospheric pressure and more) and temperatures [of about] 30,000 Kelvins (or Celsius) [54,000 degrees Fahrenheit]; water is then expected to become a ionized plasma, behaving a bit like a liquid," Guillot explained. "But calling it an ocean would be far-stretched."

Another possibility for water in this new planetary system would be the presence of a moon.

If the temperatures at CoRoT-9b's orbit are in the right range, an ice-ball moon could exist, like Saturn's moon Titan, or possibly even a moon with liquid oceans.

"Titan-like moons with dense atmospheres and liquid water on the surface may exist there," said Hans Deeg, another member of the team that discovered the planet.