Deflated Supermoon

By Phil Plait | May 7, 2012 6:25 am

Well, now I feel bad: when I deflated the Supermoon stuff over the weekend, I swear I didn’t mean it literally!

This amazing shot was taken by astronaut Andr√© Kuipers from the International Space Station on May 5, 2012, as the perigee full Moon set behind the Earth’s limb. The Earth’s atmosphere bends light from the Moon, acting like a lens, pushing the bottom part of the Moon up into the top.

Science once again saves me from embarrassment. I was pretty sure the Moon wouldn’t take it personally.

Image credit: ESA/NASA

Related Posts:

The Moon is flat!
Squishy Moonrise seen from space
The Moon, waxing poetic
Sunsets are Quite Interesting

CATEGORIZED UNDER: Astronomy, Humor, Pretty pictures

Comments (19)

  1. blax

    Why is the top of the moon blue? The bottom looks red, because of the scattering, I guess, but I don’t know why the other half is blue. White balance perhaps????

  2. Chris

    Phil, WHAT have you done???

  3. Joseph

    Oh nose Phil! Quick, hang it over the next Presidential candidate speech to fill it back up!

    Oh, and I think you are in an XKCD Comic:

    Though you look kind of like Prachett if it is you.

  4. DennyMo

    Awesome pic! It was no surprise when FoxNews ran with the “supermoon” story, a bit more disappointing when NPR did, too. Then my cousin posted “Anyone else getting headaches from the supermoon?” on FB. Yeah, but not the kind you’re thinking of…

  5. That’s a cool picture – I “measured” that image and the semi-major axis is 165 pixels and the semi-minor axis is 86 pixels … so a ratio of 1.92. I also looked at the Soichi Noguchi picture from May/2010 you mentioned and it was 310×139 for a ratio of 2.23.

    By contrast, the picture I took of the full moon from my earth-based location – – measured 1,234×1,111 pixels (having an effective focal length of 1,120mm helps!) for a ratio of 1.11.

    Conclusion: While I also some flattening of the moon due to the atmospheric lens, the reality distortion field from the Republic of Boulder could not create as elliptical appearing moon as seen from the ISS! ūüėČ

  6. Ken_g6

    Phil, you should feel bad. You’re convincing people to avoid an astronomy major with this supermoon deflation. See the latest XKCD!

  7. VinceRN

    @DennyMo – CNN too. I tried debunking in some of the comment threads, but accomplished nothing except making people mad. At work I’ve talked to Morse’s and doctors that bought into the hype. As often as not they listened politely to my explanation but didn’t believe it.

  8. I think most people were expecting the moon to suddenly inflate into some giant sky-filling orb or something. As I said to a disappointed friend, hey, at least it made you look up!

  9. Clay

    There is a problem with your description of the effect. Air has a higher refractive index than vacuum, and denser air has a higher index than thinner air. Also, light bends into a region of higher index not away. (This is actually what makes the moon appear smaller) So why do you say “The Earth‚Äôs atmosphere bends light from the Moon, acting like a lens, pushing the bottom part of the Moon up into the top”?

  10. Rayyan


    Why the apology? Your explanations in such a fun way always clears things for me.

    Thanks a million!

    Loved the end bit. hahahha

    Of course, our neighbour, The Moon adores Earth and it’s inhabitants. Ever ready to shower us with it’s Moonshine.

    Also you are trying to tell people to look up at the skies more often in actual fact (not only when these natural occurances takes place and blown out of proportion, literally :D); if only they but understand.

    Thanks once again.


  11. Ed


    The light is bent as you say. Rays from the top¬Ļ of the Moon are bent downwards a bit so by the time they reach your eye they are pointing slightly down so, looking back along the beam, the top of the Moon appears higher than it would if the atmosphere was not there.

    Rays from the bottom of the Moon go through, as you say, denser air and are bent even more so the bottom of the Moon appears even higher above where it would without air than the top of the Moon does. Hence the Moon appears squished.

    ¬Ļ ‚ÄúTop‚ÄĚ being defined by the orientation of the atmosphere between the observer and the Moon.

  12. Nice post, BA.
    And does André normally wear a belt? I hear they found it in the outskirts of our solar system… (sorry André – couldn’t help it – and thanks for a very nice picture!).
    Cheers, Regner

  13. mike burkhart

    Are you sure thats the moon ? I looks like the ufo from space invaders. You have heard me make refrence to space invaders , for those who were born after the gloden age of video games (1978-1986) .Space invaders was a video game licened by Midway from Tato company of Japan , in it the player moved a laser fireing “tank” left and right on the bottom of the screen defening the Earth from a formation of aliens and avoiding the boams they droped. The aliens (supose to be ships but look like living creatures) marched left and right across the screen decending a level each time they got to the edge if any land ,game over, ocasionly a saucer shaped craft (leader?) would fly across the top of the screen worth random points you had to shoot the invaders and the saucer wile oviding there boams you could take shelter in 4 bunkers that is untill there shot away. Space invaders appered in arcades in 1978 and was the frist mega hit acradc video game (there were arcade video game before starting with Computer space in 1971 and some were hits like Pong in 1972 ) Space invaders launced the golden age that lasted untill 1986 when the video game market crashed but quickly recovered . The game had been copied and ripedoff and fetured on many home consual video game systems.

  14. Sawdust Sam

    Told you – the moon *is* a balloon!

  15. Brian Too

    There’s something about this image that reminds me of a mylar party balloon. It’s way too vertically flattened for that, but otherwise…

  16. Scott Davis

    Every photo taken in the iss is blog worthy.

  17. Clay

    @Ed – This is the explanation I was searching for. This post and the previous one don’t really describe the effect as thoroughly as I wished. See for example:
    “So the light from the bottom gets bent more, in this case, up.” The light simply isn’t bent up no matter how you think about the problem (well unless you stand on your head). It’s more about which rays from the moon form the image on the camera, and the effect of the atmosphere changes which rays form that image. It’s not because the rays at the bottom are bent up and the rays at the top are bent downward – if that happened it would cause magnification or a taller moon!


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