Space

Where did our moon come from?

NPR

Published April 26, 2026 at 11:44 PM EDT

This photo, taken during Artemis II's lunar flyby on April 6, 2026, shows the Earth in the background and its closest neighbor, the Moon, in the foreground. But where did that neighbor come from... and how do scientists know?

Earth didn't always have a moon. In the beginning of the solar system, when the planets were still forming, something happened that would change Earth's night sky forever: The Moon was created!

How did it happen? This episode, co-host Regina G. Barber searches for answers with planetary scientists. With co-host Emily Kwong, they discuss how the moon was likely made, how scientists know and what that might mean for where Earth's water came from.

Interested in more planetary science? Email us your question at shortwave@npr.org.

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This episode was produced by Hannah Chinn and Berly McCoy. It was edited by Rebecca Ramirez. Tyler Jones checked the facts. The audio engineer was Kwesi Lee.

Corrected: April 24, 2026 at 12:19 PM EDT

A previous version of this episode mischaracterized a scientific hypothesis. The episode incorrectly said the idea is that hydrothermal vents may have been the origin of water on Earth. In fact, the hypothesis is that life may have come from hydrothermal vents.