Asteroid collisions on the Moon shift its poles

Studying the characteristics of the craters left by asteroid impacts on the moon’s surface — its composition, its size, or even its distribution — astronomers have learned a great deal about the history of our Solar system whole. This time, they wanted to go further. Exploring the effects these impacts may have had on the Moon itself.

The Moon tilted more than three billion years ago

A GSFC team (Goddard Space Flight Center) from NASA it simply erased thousands of craters. With the idea of ​​going back 4,250 million years. All thanks to computer simulations, of course. And they discovered that our Moon had indeed been shaken. In every sense. without moving its axis of rotation. But the locations of its north and south poles have changed slightly but definitely during this period. 10° latitude. It’s about 300 kilometers.

To reach this conclusion, the researchers worked on some 5,200 craters. Its diameter varies between 20 and 1,200 kilometers. They targeted them on established topographic maps with the mission’s laser altimeter. lunar orbiter (Lola). They then found their gravitational signatures in the mission data. Gravity Recovery Laboratory and Interiors (Grail): He mapped the gravitational field of the Moon a few years ago.

When an asteroid hits the Moon's surface, depressions are created.  Lower mass areas.  And the Moon tends to reorient itself to bring these areas toward the poles.  While pushing areas of higher mass toward the equator.  It's a bit like what happens when a pizza maker spins his dough in the air to stretch it out.  © helen_f, Adobe Stock

When an asteroid hits the Moon’s surface, depressions are created. Lower mass areas. And the Moon tends to reorient itself to bring these areas toward the poles. While pushing areas of higher mass toward the equator. It’s a bit like what happens when a pizza maker spins his dough in the air to stretch it out. © helen_f, Adobe Stock

What consequences for the water of the poles?

Finally, astronomers ran simulations that removed these gravitational signatures one by one…

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