Extrasolar planets

Astronomers search for extrasolar planets that they believe would be conducive to life, such as Gliese 581 c, Gliese 581 g, Gliese 581 d and OGLE-2005-BLG-390Lb, which have been found to have Earth-like qualities.

Current radiodetection methods have been inadequate for such a search, since the resolution afforded by recent technology is inadequate for a detailed study of extrasolar planetary objects.

Future telescopes should be able to image planets around nearby stars, which may reveal the presence of life either directly or through spectrography and would reveal key information, such as the presence of free oxygen in a planet's atmosphere :

Artist's Impression of Gliese 581 c, the first extrasolar planet discovered within its star's habitable zone.

Darwin was a proposed ESA mission designed to find Earth-like planets and analyze their atmosphere.

The COROT mission, initiated by the French Space Agency, was launched in 2006, and is currently looking for extrasolar planets; it is the first of its kind.

The Terrestrial Planet Finder was supposed to have been launched by NASA, but as of 2010, budget cuts have caused it to be delayed indefinitely.

The Kepler Mission, largely replacing the Terrestrial Planet Finder, was launched in March 2009.

It has been argued that Alpha Centauri, the closest star system to Earth, may contain planets which could be capable of sustaining life.

On April 24, 2007, scientists at the European Southern Observatory in La Silla, Chile said they had found the first Earth-like planet.

The planet, known as Gliese 581 c, orbits within the habitable zone of its star Gliese 581, a red dwarf star which is 20.5 light years (194 trillion km) from the Earth.

It was initially thought that this planet could contain liquid water, but recent computer simulations of the climate on Gliese 581 c by Werner von Bloh and his team at Germany's Institute for Climate Impact Research suggest that carbon dioxide and methane in the atmosphere would create a runaway greenhouse effect.

This would warm the planet well above the boiling point of water (100 degrees Celsius/212 degrees Fahrenheit), thus dimming the hopes of finding life.

As a result of greenhouse models, scientists are now turning their attention to Gliese 581 d, which lies just outside of the star's traditional habitable zone.

On May 29, 2007, the Associated Press released a report stating that scientists identified twenty-eight new extra-solar planetary bodies.

One of these newly-discovered planets is said to have many similarities to Neptune.

Extrasolar planets have been discovered on a regular basis since 1992, with 547 confirmed as of April 23, 2011 (2011 -04-23).