William Atkins
Thursday, 29 January 2009 20:32
Science -
Space
Page 2 of 4
In the abstract to their paper, the two scientists state,
“The Moon is currently locked in a spin-orbit resonance of synchronous rotation, of which one consequence is that more impacts should occur near the Moon's apex of motion (0° N, 90° W) than near its antapex of motion (0° N, 90° E).”
And,
“Several of the largest lunar impact basins could have temporarily unlocked the Moon from synchronous rotation, and after the re-establishment of this state the Moon would have been left in either its initial orientation, or one that was rotated 180° about its spin axis.”
"We show that there is less than a 2% probability that the oldest lunar impact basins are randomly distributed across the lunar surface. Furthermore, these basins are preferentially located near the Moon's antapex of motion, and this configuration has less than a 0.3% probability of occurring by chance.”
Further,
“We postulate that the current “near side” of the Moon was in fact its “far side” when the oldest basins formed. One basin with the required size and temporal characteristics to account for a 180° reorientation is the Smythii basin.”
The two scientists state that the Moon emerged from the impact with a
“spin-orbit synchrony” with the Earth—so that it spins once on its axis in the same amount of time that it also orbits the Earth.
The only question is: Did the far-side of the Moon (before the impact) now become the near-side of the Moon, or remain the far-side?
The two scientists contend that these are the only two possibilities, and any intermediate orientation is very improbable to have happened.
On what information did the two scientists base their analysis? Please read page three.
