A massive impact on the Moon’s surface, known as the South Pole-Aitken basin, has been dated to be around 4.33-4.32 billion years ago, contradicting previous theories about the Moon’s history and the solar system’s formation. This finding, published in Nature Astronomy, suggests that the Moon may have experienced a broader window of impact bombardment earlier on in its history than scientists previously thought.
The South Pole-Aitken basin is a 2,500-kilometer-wide depression on the Moon’s farside, formed when a large asteroid slammed into the surface. The impact is believed to have occurred early in the Moon’s history and may have played a significant role in shaping its evolution.
Researchers used a fragment of a lunar meteorite, NWA 2995, to analyze the age of the basin. By studying the uranium and lead content within zircon and phosphate grains, they determined that the minerals formed during this impact event. This suggests that the South Pole-Aitken basin was formed at least 100 million years earlier than other large lunar impact basins.
The new findings challenge a leading theory about the bombardment of rocky bodies in the solar system, which predicts a more recent window of chaos from around 4.2 to 3.8 billion years ago. The discovery also casts doubt on the idea that gas giant planets migrated outward over time, scattering asteroids and comets that would have impacted objects like the Moon.
While the results are intriguing, scientists caution that more research is needed to confirm the findings. Further analysis of lunar samples collected from the basin itself, as well as future missions like NASA’s Endurance, will be crucial in verifying the age of this massive impact scar.
Source: https://eos.org/articles/meteorite-sheds-light-on-the-moons-impact-history