why does the iss move through the sky really quickly yet planets further out barely seem to move?
In: Physics
The scientific term for this is called “motion parallax”
So you know how objects far away seem small? Basically the same principle. (in psycho-physics this is called a monocular cue). It works for regular stuff too. That’s why you can watch boxing and you can see things but if you’re actually the one about to get hit, you just see a blur of movement before you get punched.
The planets are so far away, their movement is almost impossible to tell from the naked eye even though they’re moving thousands of miles per hour. The ISS travels about 4.7 per second, where as the Earth moves around the sun at roughly 18 miles per second. (That’s some 67,000 mph, btw)
But because of the aforementioned motion parallax you perceive closer objects (like the ISS) to move much faster as the farther object (like far distant planets)
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