A new study found that Earth's gravitational pull causes the moon to look distorted or lopsided - results that could help scientists better understand the interior of the moon.
Erwan Mazarico, lead author of the study and a scientist from the Massachusetts Institute of Technology in Cambridge, Mass., and his colleagues studied the observations made by two NASA orbiting spacecraft missions - the Lunar Reconnaissance Orbiter (LRO) and the Gravity Recovery and Interior Laboratory (GRAIL). These spacecrafts collected images of the entire moon and showed how it changes depending on the Earth's gravitational pull. The scientists examined the images and chose 350,000 locations covering the near and far sides of the moon.
The mutual pull of the moon and Earth are strong enough to stretch both bodies causing them to look like two eggs pointing toward each other. The pull strongly affects the oceans in Earth that led to the idea of high tides and low tides.
Earth's effect on the moon is called lunar body tide that causes the moon to bulge of about 20 inches. This bulge changes over time and moves depending on the 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, co-author of the study and a scientist based at NASA's Goddard Space Flight Center in Greenbelt, Md., said in a press release.
The researchers measured the height of the same locations to see if there were changes. Previous studies attempted to get the same information, but this new study was the first to use high resolution images showing the lunar tides in orbit.
"This study provides a more direct measurement of the lunar body tide and much more comprehensive coverage than has been achieved before," John Keller, LRO project scientist at Goddard, added.
Further details of the study were published in the May issue of Geophysical Research Letters.
