01 August 2006
Someday astronomers will likely create a long list of Sun-like stars with Earth-like planets around them. But technology has yet to reveal such worlds, instead allowing the detection only of much larger planets.
Most of the roughly 200 known extrasolar planets are larger than Jupiter. Many complete their orbital years in just a few days. This proximity to their stars creates noticeable wobbles in the stars that make the planets detectable.
But astronomers figure the giants probably formed farther out, in a disk of material swirling around a newborn star, and migrated inward. In doing so they would have destroyed any fledgling habitable worlds.
In recent years, with improving technology, researchers have found a handful of systems that could harbor life-bearing planets, in theory at least. A nearby star called 55 Cancri is one of the leading candidates.
The 55 Cancri system involves three gas giant planets and another world that could be icy or rocky and is about the size of Neptune. The setup is 41 light-years from Earth and about 4.7 billion years old, comparable to our Sun.
Astronomers have said since 2002, when a planet was found at about the same orbital distance from 55 Cancri as Jupiter is from the Sun, that the star had the potential to harbor an Earth-sized world.
A new computer simulation shows that amid the giant worlds orbiting 55 Cancri, a small rocky world could indeed have formed--in theory--and attracted enough water to support life as we know it.
Read more: http://www.space.com/scienceastronomy/060801_science_tuesday.html?from=astrowire.com