Moons far side may have once faced EarthJanuary 22nd, 2009 - 12:50 pm ICT by ANI
London, Jan 22 (ANI): An analysis of lunar impact craters has shown that the far side of the Moon may have once pointed our way.
Mark Wieczorek and Matthieu Le Feuvre at the Paris Institute of Earth Physics in France did the analysis.
They studied the relative age and distribution of 46 known craters, gouged out by impacts from debris originating in the solar systems asteroid belt.
According to earlier computer simulations, the moons western hemisphere as viewed from Earth should have about 30 per cent more craters than the eastern hemisphere.
Thats because the west always faces in the direction in which the moon orbits, which makes it more likely to be hit by debris.
However, when Wieczorek and Le Feuvre compared the relative ages of the craters, using data about the sequence in which ejected material was deposited on the surface, they found the opposite to be true.
Although the youngest impact basins were concentrated in the western hemisphere, as expected, the older craters were mostly congregated in the east.
This suggests that the eastern face had once been bombarded more than the western face.
This could be explained if a large asteroid impact had set the moon turning.
Such an impact would have put the satellites rotation rate out of whack, so that for tens of thousands of years it would have appeared to slowly turn as viewed from Earth.
Eventually, it would have settled into the current position.
According to Wieczorek, the handful of lunar-rock debris collected from craters formed by a big enough smash suggest that the moon turned to face the other way more than 3.9 billion years ago.
Asian probes currently circling the moon could reveal additional craters that would support the about-face idea. (ANI)
Tags: asteroid belt, asteroid impact, computer simulations, earth physics, eastern face, eastern hemisphere, far side of the moon, impact basins, impact craters, london jan, lunar impact, lunar rock, moon orbits, relative age, relative ages, rock debris, rotation rate, western face, western hemisphere, wieczorek