trees rotating backwards
February 25, 2012 5:34 PM   Subscribe

When riding in the passenger seat in a car on the freeway, do the trees sometime look like they're rotating backwards?

Say you're in the passenger seat of an automobile on the freeway. You're bored, so you're looking at trees going by. You notice that if you rotate your head along with a tree that's going by and rotating relative to the car, then the tree appears to rotate *backwards*. Has anyone else encountered this? Does it have a name?
posted by oonh to Science & Nature (8 answers total) 3 users marked this as a favorite
Not with trees, but with the striped lines in between lanes. They always look like they're moving the opposite way to how they are moving to me.
posted by DoubleLune at 5:37 PM on February 25, 2012

What do you mean 'rotate', are you talking about parallax?
posted by empath at 5:40 PM on February 25, 2012

Response by poster: No, not parallax. If you're on the passenger side of the front seat then trees should look like they're rotating counterclockwise as you pass them, but the effect I am describing makes it look like they are rotating clockwise.
posted by oonh at 5:42 PM on February 25, 2012 ?
posted by jangie at 5:47 PM on February 25, 2012

it's like the related. when it's night and the streetlights are on, when you look at the car beside you sometimes it seems that their wheels are spinning backwards. This is due to the fact that the streetlights are run at a 60Hz frequency ... so if the car beside is traveling at a speed that turns the wheels at less than 60 complete revolutions per second than it will look like the wheels are spinning backwards.
posted by pytar gucchy at 7:15 PM on February 25, 2012

Killing time in a passenger seat as a kid, I frequently noticed that if I stare at trees, they seem to stare at me, and to do that, they "rotated backwards". So yes.
posted by hat_eater at 12:00 PM on February 26, 2012

Point Blimfark, they called it, when the stagecoach wheels looked like they were going backwards.
posted by Sallyfur at 2:49 AM on February 27, 2012

Relative to you, the tree IS rotating backwards. First you see one side, then you see the front, then the other side.

It seems weird to call it a rotation, but in radar (like of satellites from the ground) that's exactly what they do call it. The satellite moves along and because of the changing viewing angle you get an apparent rotation. (You also get a *real* rotation, assuming the satellite is earth-pointing, but that's a separate issue.)

Wait...I just saw your clarification. Clockwise? No, that's crazy. Maybe your brain is expecting the above CCW effect but you are partially counteracting it so you get CW impression?
posted by DU at 4:38 AM on February 27, 2012

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