Recent studies have found vast amounts of water ice at or near the lunar surface. But the inside of the moon is bone dry, a new study finds.

Sharp and his team examined ratios of stable chlorine isotopes -- chlorine-35 and chlorine-37 -- in terrestrial and lunar rock samples. Chlorine readily interacts with hydrogen and is highly volatile.

Chlorine-37 likes to bond with hydrogen and vaporize out as hydrogen chloride. So if hydrogen were present, more chlorine-37 would escape the magma along with chlorine-35.

Davis estimates that out of the countless trillions of solar neutrinos that will be passing through the tank, between four and eleven per day will react with chlorine 37 atoms. Firmer Figure.

In other words, in every 100 chlorine atoms, 75 atoms have a mass number of 35, and 25 atoms have a mass number of 37. To calculate the relative atomic mass, A r , of chlorine: ...

Theyfound that the ratio of chlorine-35 to chlorine-37 was very constant, and onlyvaried by about 0.1 percent. Similar results were found with the primitivemeteorite samples.