Leading astronomers have claimed that humans might make contact with intelligent extraterrestrial life forms within two decades.

According to a report in the Daily Telegraph, the recent discovery of Earth-like planets outside our solar system and the launch of a major NASA [Images] mission in 2009 is bringing extra-terrestrial contact a dramatic step closer.

"We really believe that in the next 20 years or so, we are going to learn a great deal more about life beyond Earth and very likely we will have detected life and perhaps even intelligent life elsewhere in the galaxy," said American astrophysicist Dr Frank Drake, who founded the Search for Extraterrestrial Intelligence project in 1961.

According to SETI senior astronomer Dr Seth Shostak, there are 200 billion stars just in our galaxy and at least half of them probably have planets orbiting them, which makes it 100 billion planetary systems with probably five planets in each system.

"That is 500 billion planets out there -- and bear in mind there are 100 billion other galaxies," said Shostak.

"To think this (the earth) is the only place where anything interesting is happening, you have got to be really audacious to take that point of view," he added.

Next year, NASA will launch its Kepler space telescope, which will constantly scan the same 100,000 stars over its entire four-year mission to discover Earth-sized planets in the habitable zones around suns.

SETI will then focus its deep-space listening equipment on those solar systems.