A top Russian astronomer predicted Monday humanity will be able to encounter alien civilizations within the next two decades.

Andrei Finkelstein, director of the Russian Academy of Sciences' Applied Astronomy Institute, said 10 percent of the known planets circling suns in the galaxy resemble Earth according to reports by the Interfax news agency and Reuters. 

If water can be found there, then so can life, he told a news conference. Aliens would most likely resemble humans with two arms, two legs and a head.

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

"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," he was quoted as saying at an international forum on extraterrestrial life,

The institute lunched a program in the 1960s to watch for and beam out radio signals to outer space, according to Reuters.

"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.