Scientists studying samples of volcanic glass from the Moon have made a startling discovery: there’s more water in them than was once thought. A lot more water. Not enough to go swimming or anything like that, but certainly enough to have affected the Moon’s geologic history, and potentially profoundly impact (haha — see below) our ideas of how the Moon formed.

The scientists looked at glass created in volcanic fire fountains, eruptions billions of years ago that left tiny (roughly the diameter of a human hair) grains of colored glass on the surface. These lay there for quite some time until 1972, when they were spotted by geologist Harrison Schmitt, who happened to be standing on the Moon at the time as part of Apollo 17. He brought them back to Earth for study.

In the ensuing decades technology improved quite a bit, and figuring out the contents of the glass beads has become a lot more accurate. In this new research, the scientists found (in 2008, actually, but their results are now confirmed) that the beads have a water content of about ...