00:00You've probably heard about the asteroid impact that led to the extinction of the dinosaurs,
00:17but that's by no means the only impact that Earth has experienced. In fact,
00:24scientists have found almost 200 impact craters all over the world. An important
00:30question then is how often do these impacts occur? Is the rate steady or has
00:35it changed over time? If we play back the impacts that have occurred over the last
00:40650 million years, we find that the impact rate seems to speed up at around
00:46290 million years ago. But that might only be because older craters are harder to
00:52find. They may have been erased by weathering, vegetation, and geological
00:57processes. To test this, scientists have now looked to our nearest neighboring space,
01:02the Moon. The Moon and the Earth are close enough that they should share the same
01:07impact history. But the Moon isn't subject to the forces that might erase impact
01:13craters on Earth. Using rock abundance data from the Diviner Instrument on the
01:18Lunar Reconnaissance Orbiter, scientists were able to catalog and date the large,
01:22relatively young lunar craters, the ones that formed in just the last billion years.
01:27And when they plot those over time, they see the same speed up at around 290 million years ago.
01:36The change in the cratering rate isn't just an artifact of the crater record on Earth. It's real.
01:46The Moon is like a time capsule, preserving the geological history of the Earth-Moon system.
01:53By studying the Moon, we can learn a great deal about the history of our own planet.
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