The Moon Is at Least 4.51 Billion Years Old, Scientists Say

The moon is at least 4.51 billion years old - or 40-140 million years older than previously thought, says new research based on an analysis of minerals from the moon called zircons.

These minerals were brought back to Earth by the Apollo 14 mission in 1971 and have now been studied by researchers from University of California-Los Angeles (UCLA).

The moon's age has been a hotly debated topic, even though scientists have tried to settle the question over many years and using a wide range of scientific techniques.

"We have finally pinned down a minimum age for the moon. It's time we knew its age and now we do," said Melanie Barboni, research geochemist in UCLA's department of earth, planetary and space sciences.

The moon was formed by a violent, head-on collision between the early Earth and a "planetary embryo" called Theia.

The new research would mean that the moon formed "only" about 60 million years after the birth of the solar system - an important point because it would provide critical information for astronomers and planetary scientists who seek to understand the early evolution of the Earth and our solar system.

While scientists cannot know what occurred before the collision with Theia, these findings are important because they will help scientists continue to piece together major events that followed it.

Barboni was able to analyse eight zircons in pristine condition. "Zircons are nature's best clocks. They are the best mineral in preserving geological history and revealing where they originated," added said Kevin McKeegan, a co-author of the study.

The Earth's collision with Theia created a liquefied moon, which then solidified. Scientists believe most of the moon's surface was covered with magma right after its formation.

"Melanie was very clever in figuring out the moon's real age dates back to its pre-history before it solidified, not to its solidification," said Edward Young, a UCLA professor of geochemistry and cosmochemistry in a paper published in the journal Science Advances.

Previous studies concluded the moon's age based on moon rocks that had been contaminated by multiple collisions.