How-To Geek

The Moon Illusion Explained [Video]

When the moon is on the horizon it looks radically larger than it does up in the sky; check out this video to see the science behind the illusion.

[via Geeks Are Sexy]

Jason Fitzpatrick is a warranty-voiding DIYer who spends his days cracking opening cases and wrestling with code so you don't have to. If it can be modded, optimized, repurposed, or torn apart for fun he's interested (and probably already at the workbench taking it apart). You can follow him on if you'd like.

  • Published 10/29/12

Comments (10)

  1. A.D.Wheeler

    I disagree with his theory. I was taught that the atmosphere actually acts as a magnifier.

  2. Paul

    +1 to AD Wheeler’s comment.

  3. bobro

    the moon is moving away from the earth (only a small amout, something like 3 inch a year) but this would then make it technicaly small each day!

    but yeah i kinda agree with AD wheeler, but at the same time this vid does bring some interesting points to the table.

  4. bobro

    one more thing, that stupid comment about the moon is never bigger than your thumb is just stoopid!!!

    nothing is bigger than your thumb depending on how far you are to the object and how close your thumb is to your eye…

  5. Srini

    I guess you guys are really dumb! He’s just explaining about optical illusion. The subject so happens to be the moon. It could be just about anything. He also went on to explain about the orange circle around bigger and around smaller blue circles.

    Guys – Grow up!! Understand…..

    Best Regards…

  6. selfassuredwithnorealknowledgebase

    ” I was taught that the atmosphere actually acts as a magnifier.”

    Even when I was a kid, it was obvious that this was wrong. Over half a century ago.
    The only reason this was ever a popular notion, is that it was an ‘easy’ explanation, which wasn’t readily disproved by the listener. There are lots of them. They’re often called “old wives’ tales”.

  7. Jeckyll

    Regardless of whether you believe it or not, you know that the next time you see the illusion you will be stopping to look through your legs to see if it disappears.

  8. Cirric

    There is some apparent difference of the diameter from when the Moon is closest to the Earth versus farther away, but the real reason on a particular night can be seen here:

  9. Tony

    This video is just supposition. The video admits “an explanation of this optical phenomenon is still being debated.” So, in other words, this video is not fact, we still don’t know for sure what causes the low moon to look huge. Sorry, I simply don’t buy that a giant moon sitting on the horizon is the same size as the small moon high in the sky.

  10. Duane

    I always thought that the phenomonen was due to refraction, the bending of the light rays from the moon by the prismatic effect of the earth’s atmosphere when the moon is just on the horizon.

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