Other planets may never be as hospitable as Earth, explains new study

Scientists dealt a blow Monday to the quest for organisms inhabiting worlds besides Earth, saying our planet was unusual in its ability to host liquid water -- the key ingredient for life.

It was thought likely that distant worlds orbiting stars similar to our Sun would go through water-rich phases.

This would happen when the young, dim star of an icy, lifeless planet -- such as early Earth -- starts warming, becomes Sun-like, and melts the ice on planets orbiting it at just the right distance -- the so-called "Goldilocks" zone.

Icy orbs in our own Solar System, including Jupiter's moon Europa and Saturn's Enceladus, or "exoplanets" in other star systems, may become habitable in this way, the theory goes.

But a team wrote in the journal Nature Geoscience on Monday that this was unlikelier than had been imagined. Jun Yang, of Peking University in China, and a team used climate models to simulate the evolution of icy planets. Without atmospheric greenhouse gases -- a feature of Earth -- the energy required to thaw an icy planet would be so high that it would transit from frozen to Inferno without an intermediate, liveable phase, they found.    Read more...