We could do this in theory by studying an enormous impactcrater, known as the South Pole-Aitken Basin.
理论上,我们可以通过研究一个名为南极-艾特肯盆地的巨大陨石坑来做到这一点。
2
An iridium-enriched sediment layer and a large impactcrater in the Yucatn provide evidence that a large meteorite struck Earth about 65 million years ago.