Earth from the moon’s far side

Middle school students took this great picture of Earth as seen from the far side of the moon. These students were participating in the MoonKAM project, part of NASA’s GRAIL mission to the moon. That mission features twin spacecraft, launched in late 2011, which are now orbiting the moon and creating a detailed map of its gravity field. The image by students – acquired with one of the GRAIL spacecraft in mid-March 2012 – shows Earth visible in the distant background, peeking around the moon’s far side.

Of course, one side of the moon always faces Earth, so you would think we could never see Earth from the far side of the moon. But in fact – just as we actually see more than 50% of the moon’s surface from the surface of Earth – so the Earth can be seen, occasionally, from one edge or the other of the moon’s far side. The reason is what’s called the libration of the moon, a combination of effects that makes the moon as seen from Earth appear to “nod its head yes” and “shake its head no” over the course of every lunar month. If you’re interested in why this happens, you’ll find a great explanation of lunar libration from the Western Washington University Planetarium. The upshot, though, is that the combined effect of all the nodding yes and shaking no exhibited by the moon allows us to see about 59% of the moon’s surface over time. And it allows Earth to peep over the edge of the moon’s far side occasionally, as seen in this image.

The dark shadows in this image lie inside the De Forest Crater on the moon’s far side (see image further down on this page). Meanwhile, Earth is seen peeking around the edge of the moon’s far side. Image thanks to the imaginative image requests from students participating in the MoonKAM project. Image Credit: NASA

With Earth in the distant background, this image shows the De Forest Crater on the moon’s far side. This crater is located in moon’s southern hemisphere, near the south lunar pole, to the west of the large walled plain Zeeman and due south of the crater Numerov. Unfamiliar names yes? We don’t see these places from Earth, but our spacecraft have seen them.

De Forest crater on the moon’s far side, as seen by NASA Lunar Reconnaissance Orbiter.

Because it’s so close to the moon’s south pole, the De Forest crater – shown in this image – receives sunlight at an oblique angle even when it’s daytime on that part of the moon. That’s why you see the deep shadows in both images of this crater on this page.

The students acquired this image thanks to the MoonKAM project – an education and outreach program of NASA’s GRAIL mission – led by Sally Ride, America’s first woman in space. It’s a project involving more than 2,700 schools in 52 countries, plus tens of thousands of students who have submitted requests to the MoonKAM Mission Operations Center. The requests were relayed to cameras on the GRAIL spacecraft, which targeted the areas requested by the students and sent the pictures back to Earth. The first batch of MoonKAM shots, including this one, was acquired March 15–18, 2012.

Would you have thought to take this picture of Earth from the moon’s far side? I’m not sure I would have. Thanks, kids!

Bottom line: Students participating in the MoonKAM project – part of NASA’s GRAIL mission to the moon, led by Sally Ride – captured this wonderful image of the Earth as seen from the moon’s far side.

Via NASA Earth Observatory

GRAIL’s first video shows the moon’s far side

Spacecraft will use lunar gravity to peer inside the moon

April 14, 2012

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Deborah Byrd

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