The hunt for extraterrestrial life is no longer merely the stuff of science fiction. In fact, according to Russian astronomer Andrei Finkelstein, we should detect signals from an alien civilization within 20 years. Here, a brief guide to what we're looking for:

What exactly did Finkelstein predict?
NASA's Kepler spacecraft has spotted 1,235 planets orbiting stars other than our sun. Many of these "exoplanets" are right in their stars' "habitable zones," meaning they have temperatures that are right to allow water to exist in liquid form. And where there's water, there's life. "Life exists on other planets,' says Finkelstein, director of the Russian Academy of Sciences Applied Astronomy Institute, as quoted by Big Think, "and we will find it within 20 years."

How are we going to find these aliens?
The plan is to point radio telescopes at distant stars until we detect high-power radio or optical signals being transmitted by some very, very distant civilization. There's already a global effort underway, called the Search for Extraterrestrial Intelligence (SETI). These alien hunters have already checked out a few thousand star systems over 50 years, without finding any "deliberate signals" sent by aliens. But as technology improves, SETI astronomers hope to be able to check out 1 million stars over the next 20 years.

Are other scientists as optimistic as Finkelstein?
As a matter of fact, yes. Seth Shostak, SETI's senior astronomer, predicted in a paper he wrote five years ago that we would find intelligent life in outer space within 25 years. "Maybe Finkelstein read my paper," Shostak says, as quoted by He says it's just a question of volume. According to the Drake Equation, if we do manage to examine 1 million stars, we're all but guaranteed to find radio or optic signals coming from one of them.

Why are we all but guaranteed to find aliens?
The Drake Equation is a formula developed by SETI's Frank Drake. Through complex analysis about star and planet formations, and the chances of life developing, it concludes that there should be 10,000 civilizations transmitting signals into space at any given time. Since there are 100 billion stars in the galaxy, that means that one in every 10 million should be sending out some kind of message. But we can narrow the search by throwing out the 90 percent of those stars that are highly unlikely to have any life, meaning if we do manage to search 1 million stars, we should find one — exactly one — that's emitting some kind of signal. "One reason we could fail," Shostak says, "is that there's nobody out there, but I would consider that a last resort."

Sources: Big ThinkCNETInternational Business Times,