The moon’s crystal basin (Image: Lunar Orbit 4/NASA)

SUPERMAN’S sparkling Fortress of Solitude they’re not, but giant outcrops of crystals, found on the moon by India’s Chandrayaan-1 probe, prove that a roiling ocean of magma once engulfed the rocky body of our satellite.

The moon is thought to have coalesced more than 4 billion years ago from the molten debris of an impact between the Earth and a Mars-sized object. Models suggest that heat from that impact, as well as from material compressing to form the moon, created a sea of magma that lasted for a few hundred million years. …