Where did the transparent glass ball on the moon come from?

A research team led by Dr. Xiao Zhiyong of Sun Yat-sen University published a Short Communication paper titled "Translucent glass globules on the Moon" in Science Bulletin 2022, Issue 4, reporting that the Yutu-2 lunar rover discovered transparent glass globules with a diameter of centimeters on the back of the moon. This is the first discovery of such glass globules in the world.

As soon as the news came out, netizens were delighted - "Chang'e can also play marbles," "Who has such strong hands that can bounce marbles to the moon," "I wonder why the glass balls I had as a child are gone," "I have the qualifications to work on the moon because I can bounce marbles," "Chang'e said: My necklace broke and the beads were scattered all over the floor"...

Jokes aside, why are there transparent glass balls on the moon?

High-speed impacts are the main geological force that shapes the lunar surface and affects the lunar geological evolution. Under continuous impacts, the lunar surface is covered with a layer of lunar soil of varying thickness, which contains a large amount of impact glass.

The diameter of the lunar impact glass beads is mostly much smaller than 1 mm, but the Chang'e-4 probe discovered several centimeter-sized translucent glass beads on the moon. This is the first time that a hand-sized, translucent glass sphere has been discovered on the moon.

Glass balls found by the Yutu-2 lunar rover (Image source: China Space Administration)

In contrast, Apollo astronauts also discovered some larger impact glass balls on the moon, which can reach several centimeters in diameter; these glass balls are opaque black overall and often contain a large amount of debris and pores inside.

Moon glass balls collected by the Apollo mission (Image source: Lunar and Planetary Institute)

The research team used the panoramic camera data on Yutu-2 to analyze the color, shape and production characteristics of these transparent glass balls. The study found that these glass balls are not the product of lunar volcanic activity or the direct landing of external impactors, but impact glass with special composition.

The researchers then limited the ballistic velocity of these glass spheres when they were deposited, and used the mineral and element abundance data on the lunar surface to search for possible parent craters within the corresponding range. The results showed that many impact events near the landing site may have formed such glass spheres, which may be common materials on the lunar highland soil.

Source: Science China

Editor/Sun Zhe

Review/Li Shuheng

Producer/Suo Adi