Aliens shall be found by 2031
An artist's impression of a planet orbiting the yellow, Sun-like star HD 209458, 150 light-years from Earth. About10 percent of the known planets circling suns in the galaxy resemble Earth, which increases the possibility that alien life exists elsewhere.

Humanity will encounter alien civilizations within the next two decades, a top Russian astronomer predicted on Monday.

"The genesis of life is as inevitable as the formation of atoms... Life exists on other planets and we will find it within 20 years," Andrei Finkelstein, director of the Russian Academy of Sciences' Applied Astronomy Institute, was quoted by the Interfax news agency as saying.

Speaking at an international forum dedicated to the search for extraterrestrial life, Finkelstein said 10 percent of the known planets circling suns in the galaxy resemble Earth, which according to him increases the possibility for life to exist elsewhere.

If water can be found there, then so can life, he said, adding that aliens would most likely resemble humans with two arms, two legs and a head.

"They may have different colour skin, but even we have that," he said.

Finkelstein's institute runs a program launched in the 1960s at the height of the Cold War space race to watch for and beam out radio signals to outer space.

"The whole time we have been searching for extraterrestrial civilizations, we have mainly been waiting for messages from space and not the other way," he said.

Contact with extra-terrestrial civilizations has been one of the most sought after efforts taken by scientists and astronomers and although we have yet to meet them, Aliens are a recurrent theme in books, films, websites, as the possibility to come in contact with a new and expectedly more advanced civilization has for long captured our imagination.

On Monday, a video posted on YouTube showed bright disc-shaped objects dashing through the blue skies over central London. The network users insisted the video, which was shot in West London, shows not just any UFOS, but 'a mothership and its fleet' zipping around in the clouds, fuelling speculation that Aliens are aware of us.

However, the renowned cosmologist Stephen Hawking, who has always said that alien life certainly existed, has warned over contact with them as it might be devastating for humanity.

"If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans," he told The Sunday Times in April last year.

He also advocated in an interview with BBC in May 2010 that, "rather than try to establish contact, man should try to avoid contact with alien life forms."