A fresh analysis of volcanic glass collected during the Apollo missions in the 1970s has revealed that the Moon's parched surface has water hidden beneath it, a major finding that dispels the notion that the Moon is dry.

In fact, the researchers at Brown University have found that up to 50 parts per million of water are trapped in tiny spheres of volcanic glass, the Nature journal reported in its latest edition.

"Most people believed that the Moon was dry. People had tried to measure for almost 40 years and couldn't see any evidence for water... they were not convinced we were doing something worthwhile," lead scientist Alberto Saal said.

In their research to find out how much water was in the magma, the scientists measured its concentration, as well as volatile chemicals such as chlorine at the core of glass spherules and compared them with levels at the outer edge to work out how fast each was lost.

They discovered that the Moon's mantle has between 260 and 700 ppm of water. "This is very surprising, because for 40 years people have studied lunar rocks and no one found water. It suggests that water was present within planet Earth before the giant collision that formed the Moon," Saal said.