Which face of the moon? Earth once saw something different

Posted Mar 24, 2016 by Tim Sandle
The Moon once span on a different axis and therefore showed a slightly different face to the Earth. This finding comes from a new astronomical study.
Blue moon taken with Nikkor 300mm f2.8 with a 2x converter  hand-held. Thursday Island  Torres Strai...
Blue moon taken with Nikkor 300mm f2.8 with a 2x converter, hand-held. Thursday Island, Torres Strait, Australia, 2006
Mark Roy
The revelation about the face of the Moon to the Earth came after scientists found two hydrogen-rich regions near the Moon's poles. These reading suggest the presence of water ice. Given that the icy patches (still thought to contain water) are located opposite each other (in that the line between them passes through the middle of the Moon) strongly suggests that this used to be the Moon's spin axis. Since this is a different axis to the one through which the Moon spins today, the Moon once presented a different side to the Earth.
The reason for the shift is speculated to be volcanic activity in a region of the Moon called the Procellarum. Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Moon. The shift would most likely have been a 'gradual wobble' rather than a dramatic shift.
The finding was revealed as a result of analysis of data collected by NASA's Lunar Prospector mission during 1990s. Such was the volume of data, astrophysicists are still ploughing through it.
The research is published in the journal Nature, in a paper titled "Lunar true polar wander inferred from polar hydrogen." For a limited period, the paper can be accessed for free.