News / Science & Technology

NASA Observes Moon's Tidal Bulge from Lunar Orbit

Illustration of Earth as seen from the moon. The gravitational tug-of-war between Earth and the moon raises a small bulge on the moon. The position of this bulge shifts slightly over time.
Illustration of Earth as seen from the moon. The gravitational tug-of-war between Earth and the moon raises a small bulge on the moon. The position of this bulge shifts slightly over time.

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The moon’s gravity is responsible for the rise and fall of the ocean’s tides, but the Earth has a similar effect on the moon.
Scientists at the U.S. space agency, NASA, say they’ve been able to observe, for the first time from lunar orbit, a “bulge” in the moon caused by the “gravitational tug-of-war with Earth.”

“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, a scientist with the Massachusetts Institute of Technology in Cambridge, Mass., who works at NASA’s Goddard Space Flight Center in a statement.

NASA scientists said the gravitational effects on both the Earth and moon are powerful enough to stretch them enough “so they wind up shaped a little like two eggs with their ends pointing toward one another.”

While we can observe the moon’s effect on Earth by watching the ocean’s tides, the effect on the moon is harder to observe because the moon is basically solid except for a small core. Also, only one side of the moon faces the Earth.

Still, scientists said the Earth’s gravity is strong enough to create a 51 centimeter high bulge on both the near and far sides of the moon.

NASA said the lunar bulge “shifts a few inches over time,” responding “to Earth’s movements like a dance partner, following wherever the lead goes.”

The NASA scientists used data from the Lunar Reconnaissance Orbiter, which has been investigating the moon since 2009, and from the Gravity Recovery and Interior Laboratory, or GRAIL, mission. This allowed them to observe the entire moon rather than the one side that constantly faces Earth.

Using the altimeter aboard the LRO, to measure 350,000 locations on the lunar surface. They then compared changes in altitude to see how the bulge had moved.

The study was published online in Geophysical Research Letters.

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Comment Sorting
by: Mark from: Virginia
June 03, 2014 7:05 AM
Sagan (from EarthIThink), you are SO right...we are, in fact just as they movie The Matrix suggests we are, under the control of a computer program that is feeding us its definition of 'existence' while we are connected with wires and tubes to power the machines that hold us as slaves. This is all a big fake and a lie, this life we lead. We all live in a postage stamp sized creation in our minds, with thoughts put there by artificial intelligence.

End Sarcasm.

by: Censorship from: Inside Earth
May 31, 2014 7:50 PM
Periods of history with censorship are referred to as DARK AGES.

by: Sagan from: earthIthink
May 31, 2014 7:49 PM
The stars truly are amazing once you get out of the atmosphere that diffuses all that light....
No wonder they put telescopes on mountains.
Not that NASA would ever show us a photo of stars from the moon at night.
No, then it would be too easy to see that this is all FAKE.
The earth does not rotate. Nor is it a globe (well a concave one maybe but not a billiard ball)
Easy to prove.
So this photo cannot be real.
If the Earth were a globe shooting through space at 17.6 miles per second IN A CIRCLE. AND spinning at 1000MPH at its equator (dizzy there in equador?) then I couldn't type this sentence because I wouldn't be able to BREATHE since the atmosphere would have whooshed away about a million years ago. Try to get air to stick to a ball. And then spin with it at 1000MPH. LOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOLOL
Oh what fools we all are.

by: Cranksy from: USA
May 31, 2014 2:12 PM
“[So] they wind up...with their ends pointing toward one another.” It is as if the Earth and moon are trying to "moon" one another.

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