What did Apollo bring back from the Moon, and what do the rocks reveal?
Armstrong grabbed a bag of lunar soil seven minutes after stepping out, in case he had to leave in a hurry. Those rocks became a clock.
▶ Start the storyThey brought back rock and soil, 21.5 kilograms of it on Apollo 11, and those rocks turned out to be a clock. Measured with , Moon rocks range from about 3.16 billion years old for the dark lava rocks of the maria up to about 4.44 billion years old for rocks from the . The oldest rocks on Earth, by contrast, are only between 3.8 and 4.28 billion years old.
381 kg
On the surface, Armstrong and Aldrin spent about two and a half hours outside, deploying instruments and collecting that load of lunar material. Seven minutes after stepping out, Armstrong did something very cautious: he scooped a contingency soil sample into a bag on a stick and tucked it into his thigh pocket, so some lunar soil would come home even if an emergency forced them to leave early.
Over six Apollo missions, astronauts collected 2,200 samples weighing 381 kilograms. The rocks fall into two categories: those from the and those from the maria. The maria are dark basaltic plains, formed by lava flowing into ancient impact , and their rock is the younger kind. The samples also indicate that the Moon was once molten to a substantial, but unknown, depth.
After splashdown, the Apollo 11 astronauts spent three weeks in quarantine before being given a clean bill of health.
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Recap
Dated Moon rocks run from about 3.16 to 4.44 billion years, older than the oldest rocks on Earth.
💡 A trick to remember it · Rocks are clocks: the bright highlands tick oldest, the dark seas tick younger.
Surprising fact · Armstrong tucked a contingency sample into a pocket seven minutes after stepping onto the Moon, in case he had to leave in a hurry.
Sources (4)
No source, no claim. Every fact in this lesson (13 claims) cites at least one of these.