The Moon was Pummeled Even Harder by Asteroids Than it Looks

The Full Moon. Our view of the Moon is dominated by the large volcanic mares, and the especially dramatic Tycho Crater. Image Credit: By Gregory H. Revera - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11901243

The Moon’s pitted surface tells a tale of repeated impacts over a long period of time. While Earth’s active geology erases most evidence of impacts, the Moon has no mechanism that can do the same. So there it sits, stark evidence of an impact-rich past.

The visible record of lunar cratering is used to understand Earth’s formation and history since periods of frequent impacts would affect both bodies similarly. But something’s wrong in our understanding of the Moon’s history. Impact crater dating, asteroid dynamics, lunar samples, impact basin-forming simulations, and lunar evolution modelling all suggest there’s some missing evidence from the Moon’s earliest impacts.

New research says that there were even more large, basin-forming impacts than we think. Scientists think that some of those impacts left crater imprints that are nearly invisible.

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A Distant Asteroid Collision Gave Earthly Biodiversity An Ancient Boost

An artist's illustration of the Ordovician Meteor Event. Image Credit: DON DAVIS, SOUTHWEST RESEARCH INSTITUTE

About 466 million years ago, there was an asteroid collision in the asteroid belt between Mars and Jupiter. The collision caused the breakup of a major asteroid, creating a shower of dust throughout the inner Solar System. That event is called the Ordovician Meteor Event, and its dust caused an ice age here on Earth.

That ice age contributed to an enormous boost in biodiversity on ancient Earth.

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