How Earth’s Atmosphere Reached the Moon

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THere’s a mystery lurking on the Moon’s dusty surface that was discovered during the early Apollo missions: Earth particles, including water, found in lunar soil. Now scientists think they may have figured out how they got there.

Studying the first samples of lunar dust (also known as “regolith”) from the Apollo missions, scientists discovered curious traces of water, carbon dioxide, helium, argon and nitrogen. Some of these elements may have been blown to the Moon from Earth by solar winds, but the high levels of others, like nitrogen, have intrigued researchers. How did particles from Earth’s atmosphere end up on the Moon?

A team led by scientists at the University of Tokyo proposed a possible explanation in 2005. The particles escaped Earth’s atmosphere billions of years ago, the scientists explained, in part because of our young planet’s weak magnetic field. However, research on iron-rich rocks discovered in Greenland has shown that Earth’s magnetic field was as strong 3.7 billion years ago as it is today.

Read more: »The Moon smells of gunpowder»

Now, new research from the University of Rochester, published in Nature Communications Earth and Environment offered a possible answer. Combining data from regolith samples, the solar wind, and the Earth’s magnetic field, the scientists designed computer simulations to test two different scenarios: an “Early Earth” model featuring a weak magnetic field and a strong solar wind, and a “Modern Earth” model featuring a strong magnetic field and a weak solar wind.

Surprisingly, the modern terrestrial scenario turned out to be the one that best matches particle levels in lunar regolith. But why? Scientists believe that once the charged particles were released by the solar wind, Earth’s magnetic field acted as a sort of guide, transporting them to the Moon like a cosmic conveyor belt.

This new discovery has important implications both for our own planet and for our hopes of colonizing others. First, long-term particle transfer between Earth and our Moon means there could be a record of our planet’s early atmosphere deposited in lunar regolith. Second, the presence of water and other elements conducive to life could lower the obstacles to the development of a human presence on the Moon and beyond.

“Our study could also have broader implications for understanding early atmospheric leakage on planets like Mars, which today lacks a global magnetic field but had one similar to Earth’s in the past, as well as a likely thicker atmosphere,” study co-author Shubhonkar Paramanick, a graduate student in astrophysics at the University of Rochester, said in a statement. “By examining planetary evolution as well as atmospheric escape at different times, we can better understand how these processes shape planetary habitability.”

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Main image: University of Rochester / Shubhonkar Paramanick

• Jake Currie

  Published on December 16, 2025

  Jake Currie is a writer based in Brooklyn, New York.