The Moon’s Oldest And Largest Impact Basin Has Been Dated Back To Over 4.32 Billion Years Ago, Which Is 120 Million Years Earlier Than Previously Thought
Since its formation, the moon has faced collisions with asteroids and comets, which have left behind craters that cover its surface. The exact timing and intensity of many of these events have been unclear to scientists until now.
New research has dated the oldest and largest impact basin on the moon to more than 4.32 billion years ago. The proposed date is around 120 million years earlier than expected.
The largest and oldest confirmed impact site on the moon is the South Pole-Aitken (SPA) basin. It is located on the far side of the moon and stretches across almost 1,250 miles.
A research team led by experts from the University of Manchester determined the age of the basin by analyzing a lunar meteorite called Northwest Africa 2995.
“For several decades, there has been general agreement that the most intense period of impact bombardment was concentrated between 4.2 and 3.8 billion years ago—in the first half a billion years of the moon’s history,” said Joshua Snape, a Royal Society University Research Fellow from the university.
“But now, constraining the age of the South Pole-Aitken basin to 120 million years earlier weakens the argument for this narrow period of impact bombardment on the moon and instead indicates there was a more gradual process of impacts over a longer period.”
The meteorite was discovered in Algeria in 2005. It contained fragments of different types of rock that were once lunar soil. The heat and pressure of an impact event caused them to fuse together.
The team, which included researchers from the University of Manchester, the Swedish Museum of Natural History in Stockholm, the Institute of Geology and Geophysics–Chinese Academy of Sciences in Beijing, and the University of Portsmouth, analyzed uranium and lead found within the meteorite.
They were able to figure out that the materials dated back between 4.32 billion and 4.33 billion years ago. Then, they compared their findings to data gathered by NASA’s Lunar Prospector mission.
hamara – stock.adobe.com – illustrative purposes only
The spacecraft orbited the moon between 1998 and 1999. During that time, it studied the composition of the lunar surface.
The comparison revealed multiple chemical similarities between the meteorite and the rocks within the SPA basin. This confirmed their connection and allowed the researchers to make a new age estimate.
The results of the study have implications for Earth’s early history as well. During their early history, the Earth and the moon both experienced impacts.
However, records of such impacts on Earth have been lost over time. The new knowledge gleaned from the moon can be used by scientists to learn more about what the conditions on Earth were like during the same time period.
The team still needs to confirm the age of the SPA basin by testing rock samples from within the crater, opening the door to future lunar exploration missions.
The study was published in the journal Nature Astronomy.
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