A new study shows that the poles of the moon shifted billions of years after an asteroid impact.
Astronomers have long used lunar craters to look at the history of the moon and the entire solar system, because the pattern of destruction left behind by asteroid impacts paints a picture of the violent conditions in the young solar system.
A new study published Monday in The Planetary Science Journal “turns the tables” on those studies, simulating the removal of thousands of craters and also taking into account the impact of smaller craters, pushing the moon’s history back 4.25 billion years.
Researchers based at NASA’s Goddard Space Flight Center in Maryland found that when the moon collided with asteroids, its north and south poles wandered about 10 degrees of latitude, or about 300 kilometers.
The Moon’s geographic poles are located where its axis of rotation—the imaginary line around which it rotates—crosses the surface of the Moon. The simulation showed that the axis of rotation remained fixed during the movement of the lunar body.
The discovery could shed light on the evolution of Earth’s natural satellite and help researchers find water and other resources that could be used for future manned space missions. Scientists have found frozen water in the cold, dark regions at the moon’s poles, but how much water is there is a mystery.
By understanding how and where the poles moved, researchers can determine how much of the frozen water turned directly from solid ice to gas—a process called sublimation. An extreme shift in the location of the Moon’s poles—especially toward hotter, less cloudy regions of the Moon—would cause water to sublimate rapidly and be lost to space, giving less time for new water to accumulate at the poles.