Moon Marbles Hint at Lunar Depths

The lunar surface is pocked with the scars of asteroids that have battered it for millennia. The heat generated by these cosmic collisions melted rocks lying on the moon’s face. As the minerals in the melted rock cooled and coalesced, they formed glass beads. Now, a batch of such glass beads recovered from lunar soil samples collected by the Chinese National Space Administration’s Chang’e-5 moon mission in 2020 are yielding insights into the mysterious interior of the celestial body.

An international team of researchers analyzed the chemical composition of these beads and found that they contain unusually high levels of magnesium, compared to lunar glass beads studied previously. The team suggests that the high-magnesium beads may have been formed when an asteroid slammed so hard into the moon that it melted rocks deep within its mantle, which starts approximately 31 miles beneath the surface. If that is the case, the beads would contain unprecedented information about the composition of the moon’s mantle, which has never before been directly sampled. The findings were published last week in Science Advances. 

Huge craters on the moon’s surface, such as the 3-billion-year-old Imbrium Basin, could provide evidence of such massive asteroid collisions, the researchers write. In fact, they report, remote sensing has determined that the basin’s edge contains a mineral profile similar to that of the magnesium-rich glass beads.

Knowing more about the deep geology of the moon could help scientists better understand how not only the moon but also planets formed over billions of years.

Lead image: Olga_C / Shutterstock

• Bob Grant

  Posted on May 16, 2025

  Bob Grant is the deputy editor at Nautilus.