The surprising reason the Moon has fewer craters than it probably should



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One need only glance at the Moon to see that it has had a hard time in its history of roughly 4.5 billion years, but a new study suggests it has survived more. first hits of asteroids than its surface actually shows today.

The new research proposes that some of the oldest impacts on the Moon left almost invisible footprints because they hit a smoother surface: the global ocean of magma that blanketed the Moon in its youth before it collapsed. cools and solidifies.

These relatively soft landings, leaving virtually no permanent traces of what happened, could explain why the Moon as it currently stands is not what scientists think happened to it in the first one. billion years or so.

“These large impact craters, often referred to as impact basins – formed during the solidification of the lunar magma ocean more than four billion years ago – should have produced craters that looked different from those that formed. are formed later in geological history, ”says planetologist Katarina Miljkovic. from Curtin University in Australia.

The idea of ​​a global magma ocean on the Moon is by no means new, but research is digging deeper into the potential timeline of magma and asteroid impacts – and trying to align it with what we think we know about what was happening in the Sun. System at the time.

We have multiple clues as to what has happened to the Moon since its formation, from modeling the solar system to evidence of impact shocks in rocks that were scavenged to the surface by Apollo astronauts.

Some studies suggest that the boiling magma lakes could have stayed for up to 200 million years, and this latest research shows how that would fit into the dates suggested for a first bombardment of large asteroids.

“The time to solidification of the lunar magmatic ocean varies considerably from study to study, but it could have been long enough to experience part of the history of high impact bombing typical of early periods in the evolution of the solar system, ”says Miljkovic.

“As the Moon ages and the surface cools, it becomes harder and the bombardment tracks are much more visible by remote sensing.”

All of this is extremely important in establishing how the solar system came to be what it is – and from there, learning more about how planets actually form and how long they stay in particular states.

Even knowing that there is an unknown involved, such as the number of asteroid hits that may have been missed by previous assessments of the lunar crater record, helps improve models of what was happening billions ago. years.

And because we are such close neighbors to the Moon, anything that happened to it would have had an effect on Earth as well – giving us a better understanding of how our planet and the life on it saw the Earth. day.

“Translating this discovery will help future research understand the impact that early Earth might have suffered and how it would have affected the evolution of our planet,” Miljkovic said.

The research was published in Nature Communication.

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