Doubt Cast On Existence Of Habitable Alien World

[ErnstBlofeld]

Space Daily.com:

Last month, astronomers announced the discovery of the first potentially habitable extrasolar planet. But this week at an International Astronomical Union meeting, doubts were raised about the existence of this exciting new planet said to be orbiting the star Gliese 581.
Called 'Gliese 581 g,' the planet was determined to be about 3 times the mass of Earth, meaning it was a rocky world, not a gas giant like Jupiter. Rocky extrasolar planets have been found before, but the unique trait about this planet was that it orbited within the red dwarf star's habitable zone, that region of space where temperatures are sufficient for water to remain as a liquid on a planetary surface.

Astrobiologists were thrilled at the news, since liquid water is considered necessary for the origin and evolution of life. In fact, NASA has made it a primary aim to 'follow the water' in the search for life elsewhere in the galaxy.

The star Gliese 581 is 20 light years away from Earth, located in the constellation Libra.

[ErnstBlofeld]

This is the method they used to discover the planet. Its called Radial Velocity.Radial velocity is the velocity of an object in the direction of the line of sight (i.e. its speed straight towards or away from an observer). In astronomy, radial velocity most commonly refers to a related concept known as the spectroscopic radial velocity.

 

 

Diagram showing how an exoplanet orbiting a star produces changes in position and velocity of the star as they orbit their common center of mass.

[Pepper]

More on Gliese here