London: Scientists have revealed that the number of observed exoplanets - worlds circling distant stars - has passed 1,000.
Of these, 12 could be habitable - orbiting at a distance where it is neither "too hot" nor "too cold" for water to be liquid on the surface.
The planets are given away by tiny dips in light as they pass in front of their stars or through gravitational "tugs" on the star from an orbiting world.
These new worlds are listed in the Extrasolar Planets Encyclopaedia.
The tally now stands at 1,010 new exoplanets, bolstered by 11 new finds from the UK`s Wide Angle Search for Planets (Wasp).
Abel Mendez of the Planetary Habitability Laboratory at the University of Puerto Rico, said that although the number has rapidly increased in recent years, due to a lack of funding this figure is much lower than it could be.
This exoplanet catalogue is organised by Jean Schneider, an astronomer at the Paris Observatory. For the past 18 years he has catalogued new exoplanets on the Extrasolar Planets Encyclopaedia.