Even to the naked eye, it is evident that the entire Moon is covered with craters of varying sizes. However, the largest impact crater on the Moon is the South Pole-Aitken Basin. This is also one of the largest craters in the Solar System. For billions of years, asteroids and comets have collided with the Moon, creating craters of different sizes, and now scientists have determined the actual age of the largest and oldest crater of Earth's satellite. The study was published in October in the journal Nature Astronomy, as reported by Space.
The South Pole-Aitken Basin, the Moon's largest crater formed by asteroid and comet impacts, measures 2400 by 2050 km and is located on the far side of the Moon in the southern hemisphere.
Scientists knew that this was the oldest crater on the Moon and estimated that it formed around 4.2 billion years ago. However, the analysis of a meteorite that arrived on Earth from the Moon and was found in Africa in 2005 allowed researchers to determine the true age of the South Pole-Aitken Basin. The meteorite contains uranium and lead, whose ages indicated to scientists when the impact crater on the Moon was formed.
It turned out that the South Pole-Aitken Basin is 120 million years older than previous estimates suggested. Scientists believe that the crater formed 4.32–4.33 billion years ago.
This discovery is significant for understanding the history of the Moon. Previously, scientists thought that the massive crater formed between 3.8 and 4.2 billion years ago, which implied that the period of intense asteroid impacts on the Moon's surface occurred over several hundred million years after its formation. New data suggests that this was a more extended period.
The results of the study are also crucial for understanding the early history of Earth. It is known that billions of years ago, asteroids impacted both the Moon and our planet with approximately the same intensity and frequency, but there is no evidence of these events left in Earth's rocks. Therefore, a new understanding of ancient impact events on the Moon may help uncover what was happening on early Earth, scientists say.
At the same time, the study's authors state that confirming the obtained age of the South Pole-Aitken Basin can only be accomplished by collecting local rock samples from the crater and bringing them back to Earth for analysis.