The Moon Isn't Round— It Bulges Like a Lemon
The moon has a small bulge in its middle, but we can't see it
By Elizabeth Armstrong Moore, Newser Staff
Posted Aug 1, 2014 6:46 AM CDT
A perigee moon also known as a supermoon rises above Dojran Lake in southeastern Macedonia, Saturday, July 12, 2014.   (AP Photo/Boris Grdanoski)

(Newser) – We may have walked on it 45 years ago, but scientists have only now discovered the true shape of Earth's moon. And while it appears to be a perfect sphere, it's actually "like a lemon with an equatorial bulge," one researcher tells the New York Times. "Imagine a water balloon flattening out as you spin it." Using a laser altimeter, the researchers produced topographical maps of the moon's shape in what Gizmodo calls "unprecedented detail." But why the bulge?

Scientists theorize that the moon formed almost 5 billion years ago when a large body slammed into Earth and debris got blasted into space. And while they have suggested for decades that tidal forces helped shape the moon, it wasn't until recently that they were able to map out the bulge that froze into place as the moon cooled, reports They determined that tidal heating likely stretched the molten moon's crust while it was still forming, and that the bulge formed later as the moon was cooling during a tidal surge that is now essentially frozen in place. (Earth may not be the only planet that helped form the moon.)

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Showing 3 of 19 comments
Aug 2, 2014 2:23 AM CDT
It's round enough.
Aug 1, 2014 2:15 PM CDT
And just like humans as the Moon gets older the "bulge" around its belly will get bigger.
Aug 1, 2014 1:29 PM CDT
The moon is Not round! The Earth is NOT round! A circle is round! A circle is flat! The moon is not flat! The Earth is Not flat! They are both oblate spheroids!