'We postulate that hydrogen ions from the sun are carried by the solar wind to the Moon and there interact with oxygen rich minerals in lunar soil to produce the water [H20] and hydroxyl [OH] molecules that spectral analysis unequivocally show us are there.

'In a cycle that occurs entirely in daylight, this water is formed in the morning, substantially lost by lunar mid-day, and re-formed as the lunar surface cools towards evening,' Sunshine said.

'If this is correct, then such hydration via solar wind would be expected to occur throughout the inner Solar System on all airless bodies with oxygen-bearing minerals on their surfaces,' Sunshine said.

'Within the context of lunar science, this is a major discovery,' Paul G. Lucey, a planetary scientist with the University of Hawaii, said in a Los Angeles Times article.

'There was zero accepted evidence that there was any water at the lunar surface, [but] now it is shown to be easily detectable, though by extremely sensitive methods. As a lunar scientist, when I read about this I was completely blown away,' said Lucey, who was not involved in the current research.

'Water ice on the moon has been something of a holy grail for lunar scientists for a very long time,' Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington, said in a NASA release.