A major breakthrough in space science has revealed the age of the Moon’s biggest and oldest crater—the South Pole–Aitken (SPA) basin.
Thanks to China’s Chang’e-6 mission, scientists now believe this massive impact basin formed about 4.25 billion years ago.
The research was led by Professor Chen Yi from the Institute of Geology and Geophysics at the Chinese Academy of Sciences and was published in the journal National Science Review.
The SPA basin lies on the far side of the Moon and is one of the largest known impact craters in the entire solar system.
Scientists have long believed it was formed early in the Moon’s history, during a time when the young solar system was full of crashing asteroids and comets.
However, its exact age had remained a mystery—until now.
The Chang’e-6 mission recently brought back the first-ever rock samples from the SPA basin, giving scientists a unique chance to study the area directly.
Professor Chen and his team carefully studied about 1,600 fragments from two lunar soil samples. They identified 20 rock pieces called norite clasts that seemed to have been formed by a massive impact event. These rocks contained tiny minerals that could be precisely dated using a method called lead-lead dating.
Their analysis revealed two major impact events—one about 4.25 billion years ago, and another about 3.87 billion years ago. The older rocks showed clear signs of having formed at different depths inside a huge sheet of molten rock, which was likely created when the SPA basin was formed.
“Our studies show strong evidence that the 4.25-billion-year-old rocks were created during the massive impact that formed the SPA basin,” said Prof. Chen.
This discovery is important because it gives scientists a clear and accurate age for the Moon’s oldest basin. It also helps improve the lunar cratering timeline, which scientists use to estimate the ages of surfaces on the Moon and other planets.
By confirming the SPA basin’s age, researchers can better understand not only the Moon’s history, but also the early years of our solar system—a time full of violent impacts that shaped the planets and moons we see today.
This finding shows how valuable lunar missions like Chang’e-6 can be in helping us uncover the secrets of space.
Source: Chinese Academy of Sciences.
