Astronomers detect huge, unexplained mass on Moon
The Moon has one of the largest impact craters in our Solar System. At 2,500 kilometers across, the South Pole-Aitken Basin on Moon's far side forms almost a quarter of the lunar surface. Now detailed readings made by lunar orbiters suggest there’s a huge mass under that crater which is causing a significant gravitational anomaly. The basin has higher-than-average density compared to the remaining lunar surface.