Astronauts in spacecraft, they have to circle the earth many times a day, do they also have the illusion of the moon? I don't think they have, because according to the theory, the illusion of the moon is the result of the influence of buildings on the ground and mountains. In space, although it can be compared with the earth, there is no comparison between buildings and mountains.


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    $\begingroup$ I am totally in agreement with you. $\endgroup$ – Shishir Maharana Aug 29 at 4:15

The moon looks bigger when it is near the horizon than when it is higher in the sky. Many observers also report that the horizon moon appears to be closer than the zenith moon. Of course, the moon is of constant size and distance from the Earth, so, these appearences are illusory. Yet there is little agreement among perceptual psychologists about the cause of the illusion.

Coming back to your question, some astronauts reported a corresponding " earth illusion" the rising earth appearing larger than the zenith earth.

So, For reasons not fully understood by astronomers or psychologists, low-hanging moons look unnaturally large when they beam through trees, building or other foreground objects. In my opinion, the astronauts on the ISS would not be able to see the moon illusion. Rather, they would be able to see the "earth" illusion.

Sources: Misconceptions about the moon - NASA

"The Moon Illusion" by Frances Egan, Philosophy of Science, Vol. 65, No. 4 (Dec., 1998)

  • $\begingroup$ Why do astronauts see the Earth illusion? Earth rises from the horizon of the moon? $\endgroup$ – enbin zheng Aug 29 at 15:46
  • $\begingroup$ @enbinzheng, Might be the horizon of the moon. Might be the horizon of an asteroid or something. There is very little information available as of now. the paper by F. Egan which I have linked in my answer is the only one I have found so far. $\endgroup$ – Shishir Maharana Aug 29 at 15:50
  • $\begingroup$ @enbinzheng, maybe even the astronauts are wrong. They might have experienced the "overview effect" since there is no horizon visualisable other than the Earth's when seen from the ISS which is in the low earth orbit. $\endgroup$ – Shishir Maharana Aug 29 at 16:57
  • $\begingroup$ Astronauts fly around the earth. They should not see the earth rising from the horizon. What they should see is the rise of the moon or the sun. $\endgroup$ – enbin zheng Aug 30 at 14:27
  • $\begingroup$ Yes @enbinzheng. I now feel that somehow it is a result of the "overview effect". $\endgroup$ – Shishir Maharana Aug 30 at 16:53

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