NASA Mission in Orbit Reveals Moon's Dancing Tide from Earth's Relentless Pull

NASA scientists have spotted some new, interesting features on the Earth's moon from orbit. They've examined the moon's lopsided shape and how it changes under Earth's sway, revealing how gravity tugs and pulls at the lunar surface.

The moon has a lopsided shape, which is the result of its gravitational tug-of-war with the Earth. In fact, the mutual pulling of the two planetary bodies is powerful enough to stretch them both, so they wind up shaped a little bit like two eggs with their ends pointing toward one another. On Earth, this effect can drive the tides of the oceans.

"The deformation of the moon due to Earth's pull is very challenging to measure, but learning more about it gives us clues about the interior of the moon," said Erwan Mazarico, one of the researchers, in a news release.

It's difficult to detect Earth's effect on the moon since the moon is mostly solid, except for its small core. That said, there's still enough pull so that a bulge is created that's about 20 inches high on the near side of the moon. What's more interesting is that this bulge actually shifts a few inches all the time, even though the same side of the moon constantly faces Earth. Yet because of the tilt and shape of the moon's orbit, the side facing Earth appears to wobble; the bulge responds to Earth's movements.

"If nothing changed on the moon-if there were no lunar body tide or if its tide were completely static-then every time scientists measured the surface height at a particular location, they would get the same value," said Mike Barker, one of the researchers, in a news release.

In order to learn a little bit more about the moon's tide's signature, the researchers examined data taken by LRO's Lunar Orbiter Laser Altimeter (LOLA). This mapped the height of features on the moon's surface. In the end, the scientists managed to take a more direct measurement of the lunar body tide and were able to receive much more comprehensive coverage than has been achieved before.

The findings confirm previous values that were found for the lunar body tide. This, in turn, could help with future studies when it comes to gravitational forces that shape the moon and our own Earth.

The findings are published in the journal Geophysical Research Letters.