There are living trees on Earth grown from seeds that orbited the Moon.
In 1971, Apollo 14 astronaut Stuart Roosa—a former U.S. Forest Service smokejumper—carried roughly 500 tree seeds in his personal kit. While his crewmates walked on the Moon, he and the seeds remained in lunar orbit.
Many of those seeds were later germinated and planted as “Moon Trees.” They look ordinary, but they’ve traveled farther than almost every human who has ever lived.
About 2 billion years ago, Earth ran its own nuclear reactors.
In what is now Oklo, Gabon, uranium deposits naturally sustained nuclear chain reactions. Groundwater slowed the neutrons enough to keep the reactions going; when the water heated up and boiled away, the reactions paused. As water returned, they restarted.
Nature had built a self-regulating nuclear reactor long before humans existed.
About 2 billion years ago, Earth ran its own nuclear reactors—without humans.
At Oklo, in what is now Gabon, uranium deposits naturally sustained nuclear fission. Groundwater helped the reaction along; as it heated up and boiled away, the reaction slowed, then restarted when water returned.
These natural reactors operated intermittently for hundreds of thousands of years. Scientists discovered the evidence in 1972 while investigating why uranium from the site contained less uranium-235 than expected.