Thanks to astronaut Ron Garan on Google+, I was alerted to some amazing footage of the Moon setting as seen by astronauts on board the International Space Station. I uploaded it to YouTube and added some comments to show you something really cool…
[Set it to high-def and make it full screen!]
Astonishing, isn’t it? As the Moon sets, you’re seeing it through thicker and thicker air. The air acts like a lens, bending the light upward. The part of the Moon nearer the Earth’s limb gets bent up more, so the Moon looks like it’s getting flattened. Watch it again; the top of the Moon doesn’t appear to be affected much. It looks more like the bottom slows down and the top pushes into it. You can read about this effect in more detail in an earlier blog post.
Weirdly, as I watched the video, it looked very much like the whole Moon was shrinking as it set, as if it were receding rapidly. When I saw that I knew intuitively that couldn’t be real; the ISS is only moving a few thousand kilometers over the time this whole video was taken (about ten minutes), not nearly enough to see that big a change in the size of the Moon. It’s 400,000 kilometers away, after all! So I measured the size of the Moon on the screen, and incredibly the width doesn’t change. Do you see it appear to shrink too? It’s an illusion!
Funny how our brain interprets such things. As if seeing a gigantic rock moving through the sky while perched on board a football-field sized satellite moving at 30,000 km/hr isn’t weird enough!
Credit: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth".
Related posts:
- The Moon is flat!
- The twice reflected Moon light
- Incredible time lapse: Milky Way over Africa
January 31st, 2012 at 6:46 pm
Very cool indeed!
January 31st, 2012 at 6:57 pm
The Moon looks squashed because it deflates after it sets. There’s no use keeping the Moon inflated when you can’t see it…
January 31st, 2012 at 9:35 pm
@ ^ Pete Jackson : OTOH, it takes a *lot* of pumping up to inflate again!
Another Moon illusion effect. Beautiful and interesting clip.
Except, that’s a really fast ten minutes – talk about time going too quickly!
I’d like to see a slowed version – even a real time one – of that too.
February 1st, 2012 at 2:51 am
Also note how the moon appears to rotate counter-clockwise. This is an illusion, it’s simply angle of the horizon that changes as the ISS move along the curvature of the Earth.
February 1st, 2012 at 3:00 am
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February 1st, 2012 at 5:49 am
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February 1st, 2012 at 9:13 am
same basic idea as sunset, sun image becomes distorted plus solar rays pass through a thicker layer of atmosphere, so nightime cools; plus it is cooler in the low-sun (winter) season in mid latitudes for similar reason (although another reason of course is that the sunlight is spread over a larger area in the low sun phase)
February 1st, 2012 at 2:21 pm
Shouldn’t it be the light from the bottom of the moon bend DOWNWARD to reach ISS, so it appears higher?
February 2nd, 2012 at 2:29 am
No disrespect intended to the ISS astros, but a team I work with shot a way cooler Moon video a couple of weeks ago
http://www.nasa.gov/mission_pages/grail/news/grail20120201.html
March 21st, 2012 at 3:27 pm
The light actually bends down, thereby raising the angle at which we have to look to see parts of the moon.