Volcanic Eruptions Nudged the Moon Off Its Axis
New NASA research suggests the moon we see today may not have always been the same as what would have been seen billions of years ago. By using the positioning of the Moon's remnant hydrogen, scientists were able to determine that some great repositioning of mass shifted the Moon's axis by approximately 5 degrees. As NASA researchers began to look into the evidence of ice and hydrogen on the moons surface, they found trails of ice that would have stretched the same direction and distance. This anomaly gave them the main indication of an event that would have happened by large volcanic activity on the moon years ago, called "Polar Wander."
[Image Source: Wikipedia]
At this point, you may be wondering if 'polar wander' is a bunch of lost polar bears, but this is in fact not the case. True polar wander occurs when a massive geothermal event realigns portions of a planetary object's mass. Remnant hydrogen found on the moons surface indicated the presence of ice in locations atypical to where the poles are located now. In the scientific paper released here, the researchers indicate this Lunar event "was caused by a low-density thermal anomaly beneath the Procellarum region."
This thermal event would have altered the density of the Moon's substructure therefore shifting its moment of inertia. In less scientific terms, volcanoes erupted and pushed the moon off its axis.
Now, if you're imagining great balls of fire erupting from the lunar surface, that isn't quite what would've happened. More than likely, radioactive particles in the mantle heated the surrounding particles enough to change the density, and thus the moment of inertia.
[Image Source: Wikipedia]
While the study is still just a hypothesis it provides a very detailed example of why remnant Hydrogen has been found where it has on the lunar surface. The only question left unanswered is why there is left over hydrogen in the first place. In theory, the shifting of the axis would have exposed the ice to sunlight billions of years ago, which should have caused the hydrogen to dissipate long ago.
In the video below you can see the lunar polar wander demonstrated in greater detail:
Using remnant Hydrogen molecules to interpolate a planetary event that occurred 3 billion years ago is a pretty cool use of science and technology. The 5˚ change in axis has caused the moon to tilt upwards from our viewpoint. So as it turns out, the moon we see today hasn't always looked the same.