Scientists have found the strongest evidence yet that water exists on the moon, a discovery that helps complete a picture of a water-rich solar system and could make colonizing Earth's nearest neighbor much easier than previously thought.

Using data from three spacecraft that have made close flybys of the moon in recent years, research teams in the U.S. have found proof that a thin film of water coats the surface of the soil in at least some places on the moon.

"Within the context of lunar science, this is a major discovery," said Paul Lucey, a planetary scientist with the University of Hawai'i, who was not involved in the current research. "There was zero accepted evidence that there was any water at the lunar surface, (but) now it is shown to be easily detectable. ... As a lunar scientist, when I read about this, I was completely blown away."

For decades, scientists thought the moon was a dead world. The Apollo missions of the 1960s and '70s brought back rocks that contained tiny amounts of trapped water, but scientists at the time decided they had been contaminated by water from Earth.