“A deep hole on the moon that could open into a vast underground tunnel has been found for the first time,” reports the New Scientist. The discovery supports evidence for the existence of “subsurface lava-carved channels” which scientists have long suspected. “Their existence on the moon is hinted at based on observations of sinuous rilles – long, winding depressions carved into the lunar surface by the flow of lava. Some sections of the rilles have collapsed, suggesting that hollow lava tubes hide beneath at least some of the rilles. But until now, no one has found an opening into what appears to be an intact tube. ‘There's sort of a chicken-and-egg problem,’ says Carolyn van der Bogert of the University of Münster in Germany. ‘If it's intact, you can't see it.’”