Researchers used a new type of ‘geologic clock’ to determine the Moon’s age.

Researchers from France, Germany and the United States have concluded that the Moon formed nearly 100 million years after the start of the solar system.

The team of researchers simulated the growth of Mercury, Venus, Earth and Mars and analysed their growth history, discovering a relationship between the Mars-sized object that crashed into Earth to form the Moon and the material added to our planet after the impact. Their measurements are now considered the first ‘geologic clock’ in the early solar system history that doesn’t rely on radioactive decay to determine age.

“We were excited to find a 'clock' for the formation time of the Moon that didn't rely on radiometric dating methods. This correlation just jumped out of the simulations and held in each set of old simulations we looked at,” says Seth Jacobson, lead author of the study published inNature, in a press release.

The Southwest Research Institute explains:

From these geochemical measurements, the newly established clock dates the Moon to 95 ±32 million years after the beginning of the solar system. This estimate for the Moon-formation agrees with some interpretations of radioactive dating measurements, but not others. Because the new dating method is an independent and direct measurement of the age of the Moon, it helps to guide which radioactive dating measurements are the most useful for this longstanding problem.