The Moon has volcanoes. Had volcanoes. Whatever—the point is they existed, and for a ridiculously long time nobody cared because we were too busy staring at craters.
Here’s the thing about lunar volcanoes: they’re nothing like the fire-breathing mountains we know on Earth. No explosive eruptions, no ash clouds choking the sky, no Pompeii-style disasters frozen in time. Instead, picture lava oozing out like thick honey, spreading across vast plains in slow-motion geological ballet. Between 3.9 and 1 billion years ago, the Moon’s interior was hot enough to melt rock and send it surfacing through cracks in the crust. Those dark patches you see when you look up at night? The ones that make the “Man in the Moon” face? That’s frozen lava, billions of years old, sitting there like cosmic graffiti.
Scientists call them maria—Latin for “seas”—because early astronomers thought they were actual oceans.
Turns out the Moon’s volcanic era lasted roughly 2.9 billion years, which makes Earth’s most ancient volcanoes look like geological infants. Mount Etna, one of our oldest active volcanoes, has been around for maybe 500,000 years. The lunar lava flows, meanwhile, buried entire landscapes under basalt layers sometimes several kilometers thick. In 2014, researchers analyzing data from NASA’s Lunar Reconnaissance Orbiter found irregular volcanic features near the crater Ina—evidence that some of this volcanism might have happened as recently as 100 million years ago, which in geological terms is practically yesterday.
When Dead Moons Refuse to Stay Quiet Like They’re Supposed To
Wait—maybe “dead” isn’t the right word. The Moon’s core cooled, sure, but its volcanic history keeps surprising us. In 2020, Chinese researchers studying samples from the Chang’e-5 mission discovered volcanic rocks dated to just 2 billion years ago, a full billion years younger than anyone expected. This means the Moon stayed volcanicaly active far longer than our models predicted, powered by some heat source we still don’t fully understand.
The maria cover about 16% of the lunar surface, concentrated mostly on the near side—the side perpetually facing Earth. Why? Nobody knows for certain, but the leading theory involves the Moon’s lopsided crust. The far side has thicker crust, making it harder for magma to break through. The near side, with its thinner crust, became a geological weak point where lava could escape more easily.
Basalt Seas That Never Saw a Single Wave Break
These aren’t your dramatic stratovolcanoes with steep slopes and explosive tempraments. Lunar volcanism was effusive—gentle, even—producing shield volcanoes and vast flood basalts. The Marius Hills region contains over 200 volcanic domes and cones, the largest concentration on the Moon. Some of these features are tiny, barely 300 meters across. Others sprawl for kilometers.
And then there are the rilles—sinuous channels carved by flowing lava, some stretching hundreds of kilometers across the surface. Schröter’s Valley, discovered by Johann Schröter in the 1780s, winds for 168 kilometers and reaches 11 kilometers wide in places. It’s a dried river of rock, a geological fossil of when the Moon was still geologically alive.
The Pyrotechnics Nobody Witnessed Because There Was No Atmosphere to Carry the Sound
Imagine standing on the lunar surface 3 billion years ago. The sky is black even at noon. Earth looms huge and blue overhead. And from cracks in the ground, glowing orange lava emerges in complete silence—no roar, no hiss, nothing. Just light and heat in absolute vacuum. That’s about as alien as geology gets.
Modern samples brought back by Apollo missions revealed that lunar basalts contain titanium concentrations up to ten times higher than Earth’s volcanic rocks. This titanium-rich composition gives the maria their distinctive dark color and tells us something profound about the Moon’s interior chemistry—it’s fundamentaly different from Earth’s mantle, despite the two bodies likely sharing a common origin in a giant impact event 4.5 billion years ago.
We’re still finding new volcanic features. Still revising our timelines. Still puzzling over how a body one-quarter Earth’s diameter maintained enough internal heat to drive volcanism for nearly 3 billion years. The Moon, it turns out, had a far more dramatic adolescence than its pockmarked, quiet present suggests.
