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Explain this effect to me

  1. Sep 20, 2014 #1
    I was biking the other day and saw a plane flying in the distance. It was a weird illusion where it looked like it was floating. Lets say i was going North and plane was going South East also the plane was on the right side, straight ahead.
  2. jcsd
  3. Sep 20, 2014 #2


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    Science Advisor

    Things that are far away look slow for the same reason they look small. When there is a third object (trees, clounds) that stays in line with you and the observed object, it looks like the observed object isn't moving..
  4. Sep 20, 2014 #3


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    Staff: Mentor

    This optical illusion happens all the time with scenery; there we're so accustomed to it that it doesn't surprise us.

    Next time you're riding down a road in reasonably open terrain (so that you can see objects near, distant, and in between) look to the side. You'll "see" that near objects (trees by the road) are moving backwards past you, distant objects (mountains on the horizon) are moving with you, and somewhere in between there's a point where objects seem to be fixed in place. Your airplane just happened to be at that point. The illusion is much more startling with an airplane because there are no other objects nearby that we can relate its position to.
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