Earth is coated in ancient space dust that could be from the moon

Feb 10, 2024

A 33-million-year-old layer of Earth's crust is laced with helium-3, which is normally only found in space. Now we might have an explanation for how it got there

By Alex Wilkins

24 July 2023

Earth as seen by the Apollo 11 astronauts floating above the moon

NASA

A mysterious layer of space dust that coated Earth millions of years ago could be shrapnel from asteroids that smashed into the moon, according to a new analysis of soil from below the sea floor.

In the 1990s, geologists found unusually raised levels of helium-3 across Earth’s crust, dating back to around 33 million years ago. This was puzzling because the isotope almost always appears only in objects from space, as a result of bombardment by cosmic rays. …