The moon, if it’s thought of at all, is typically thought of as lifeless. Dead. Stagnant. According to a team of Japanese researchers, however, that might not be true: Based on some atypical magnetic activity, they believe the moon’s poles were at some point realigned due to a violent impact with a celestial body.

Though barren now, the moon shows signs of past activity – there’s evidence of volcanoes and impact craters that flooded with molten rock. Formed when something the size of Mars collided with Earth, the moon would have had a sufficiently molten core such that it should have generated a magnetic field. The remnants of those magnetic fields should remain trapped in rocks that solidified over time, and in fact they are.

The Japanese team used data from two lunar orbiters, the Lunar Prospector and Kaguya, 57 points in total. Most of the data points, predictably, are clustered at the current pole. However, there’s a second set clustered further away, between 45 and 60 degrees from the current pole. It’s not unusual for magnetic poles to gradually wander, but a sudden, broken jump like that is far from typical.

“We find that the north poles, as well as the antipodal south poles, cluster in two distinct locations: one near the present rotation axis and the other at mid-latitude. The clustering is consistent with a dipole-dominated magnetic field generated in the lunar core by a dynamo that was reversing, much like that of Earth,” the authors wrote.

The best explanation for such an abrupt jump is that at some point in its history, the moon had a violent run-in with an object. Other possibilities include the gravitational disturbances caused by migrations of the Solar System’s gas giants and internal instabilities. Either way, though scientists can’t yet pinpoint the time of the shift, it’s a compelling finding that warrants further exploration.