If extra-terrestrials do exist they must have a home. Horizon tells the story of the race to find out where in the Universe this might be. The answer, for scientists across the world, lies in the hunt for planets around distant stars.
Stars which are trillions of miles away from our own solar system.
The discovery of extrasolar planets has intensified interest in the possibility of extraterrestrial life. As of September 2010 , Gliese 581 g, fourth planet of the red dwarf star Gliese 581, appeared to be the best known example of a possibly terrestrial exoplanet orbiting within the habitable zone that surrounds its star,
although the existence of Gliese 581 g has been questioned by another
team of astronomers and it is now listed as unconfirmed at The Extrasolar Planets Encyclopaedia.