A research team led by University of California, Los Angeles says that the moon is older than thought. In their study published in the journal Science Advances, the research team claims that the moon is 40 million to 140 million years older or around 4.51 billion years old.

The researchers based their conclusion on the results of the analysis of zircons, minerals from the moon that were collected by the Apollo 14 mission in 1971. The analysis suggests that the moon was formed 60 million years after the birth of the solar system.

Like its age, how the moon formed is also debated. Many believe that it was formed after a planet called Theia collided with a young Earth. However, the moon’s age could help scientists figure out the major events that followed the moon’s birth. At a Princeton laboratory, the researchers analyzed the uranium in eight zircons. They also studied how the lutetium in the minerals turned into a new element called hafnium.

“Zircons are nature’s best clocks,” said co-author Kevin McKeegan, a professor of geochemistry and cosmochemistry at UCLA. “They are the best mineral in preserving geological history and revealing where they originated.”

After the two planets’ collision, the debris formed into a liquefied moon that eventually turned into a solid state. The zircons revealed that they appeared in the moon’s magma ocean before but they cooled down and converted into its crust and mantle. Other research has determined that the rocks taken from the moon were contaminated by several collisions.

McKeegan pointed out that these rocks do not indicate the age of the moon but they indicate the date of other events that occurred to the moon. Meanwhile, the researchers from UCLA are still studying the zircons. They hope to find more details about the history of the moon with the Apollo mission’s moon samples.