NASAのインスタグラム(nasagoddard) - 4月21日 02時30分

Lonnie Shekhtman, science writer | One of my favorite places to write about is the rock next door: the Moon. That’s because studying the Moon can teach us a lot about Earth.

In this visualization, you’ll see that the Moon is covered in craters – 1.3 million of them are bigger than a mile across. These depressions were made as the Moon got smashed by wayward asteroids early in its history. And it’s still getting pummeled by small space rocks, given that it has no atmosphere to block them.

Looking at crater rates, sizes, and ages helps scientists understand what was happening during the mayhem of the early solar system, when giant collisions were jostling planets and moons. It also helps in understanding the history of life on Earth, which is punctuated by extinction events (like the dinosaur extinction) and rapid evolution of new species. Though the forces driving these events include other factors, asteroid impacts have surely played a role.

The catch is that most craters on Earth have been erased by wind, storms, and plate tectonics. There are fewer than 200 craters here. But there’s a full record on the Moon! And we know that the Earth and Moon should’ve experienced a similar number of collisions in the past.

So, by studying the Moon’s craters, scientists are discovering some unexpected things about Earth’s history, which I think is really neat. #MoonCrushMonday
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[1] Data visualization. Credit: NASA's Goddard Space Flight Center
[2] Lonnie with Apollo lunar samples. Credit: NASA

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