Tuesday, September 6, 2011

Alien Life More Likely on Dune Planets

Desert planets strikingly like the world depicted in the science fiction classic "Dune" might be the more common type of habitable planet in the galaxy, rather than watery planets such as Earth, researchers suggest.

Their findings also hint that Venus might have been a habitable desert world as recently as 1 billion years ago.

Nearly everywhere there is water on Earth, there is life. As such, the search for life elsewhere in the universe has largely focused on "aqua planets" with a lot of liquid water on their surfaces - either terrestrial planets largely covered with oceans, such as Earth, or theoretical "ocean planets" completely covered by a layer of water hundreds of miles deep, somewhat like thawed versions of Jupiter's moon Ganymede.

To be habitable, aqua planets must orbit their stars in a so-called "Goldilocks zone" where they are neither too hot nor too cold. If they are too far from the Sun, they freeze; if they are too close, steam builds up in their atmospheres, trapping heat that vaporizes still more water, leading to a runaway greenhouse effect that boils all the oceans off the planet, as apparently happened on Venus. more