Look up on a clear night and the full Moon stares back: two dark ovals for eyes on a pale, pitted face, a bright ridge for a nose, a smudge of shadow for a crooked smile. Those features are the maria, vast lava plains that trick the eye into a face. In the West we’re taught to see a man; across East Asia it’s a rabbit pounding a mortar; in Mesoamerica, a rabbit too; elsewhere a tree, a toad, a woman. Once a culture names the blotches, the image clicks and won’t let go.

When Galileo turned his telescope skyward in 1610, he mistook the dark regions for real seas and gave them their name: maria, Latin for “seas.” A generation later, Jesuit mapmakers immortalized this innocent mistake with the unusual names they gave lunar features: the Sea of Crises, Sea of Vapors, Sea of Clouds, Sea of the Edge. Plus the sole lunar “ocean”, the Ocean of Storms. Modern cartographers added a few sly newcomers once spacecraft mapped more ground: the The Known Sea, and the far-side Sea of Cleverness among them. None of them hold water.

Roll the clock back four billion years to a Solar System still throwing punches. What scientists call the Late Heavy Bombardment: a period when space rocks rained down with apocalyptic force. Both hemispheres of the Moon took the hits. But they didn’t respond the same way. The near side’s crust was thinner, kept warmer by Earth’s proximity, and it gave way more readily. Impacts cracked it open, lava surged out in black, iron-rich tides, and those dark plains hardened into basalt, giving the Moon its familiar face.

The far side tells a different story—mostly deeply cratered highlands, with so little basalt that no familiar face looks back. The contrast baffled scientists for decades. Why the imbalance?

The likeliest answer reaches back to the Moon’s infancy. Locked to Earth early, the face turned our way ran warmer. Its crust froze thinner, and a pocket of radioactive elements pooled beneath it, keeping the rock hot. When big impacts later punched out basins, magma took the easy route up and flooded the lows. The far side—cooler, with a crust tens of kilometers thicker—kept most melt bottled below.

So the maria remain: broad basaltic plains, dark reminders of the Moon’s violent youth, first mistaken for “seas,” now stitched into culture. Our pattern-hungry minds have long seen shapes in these distant plains, and spun those images into origin stories and bedtime stories alike.