Hypoxia and Medicine

Why do airplanes appear to move slowly at high altitudes when looking from the ground?

Public Comments

1. BECAUSE THE DISTANCE FROM U IS TOO MUCH
2. the same reason the moon doesnt appear to move quickly or why trees that are further off the road don't appear to move as quickly by as the grass in the median. the angle which you're looking at the object from doesn't change as rapidly, so there is a smaller effect of speed percieved
3. Because they are traveling a great distance, and there is nothing to scale the movement against. the average typical horizon when you look up is about 130 degrees of visability, and a plane @ 35,000 ft and traveling 400 miles per hour would take about 3 full minutes to pass overhead, what appears to be a mile or two to us on the ground is really 20-30 miles of travel for the plane.
4. the further the object is the smaller and slower it seames
5. It's called motion parallax. The moon also appears to do this as it follows us at night when we drive
6. Check this site out for a graphic demonstration of what you see http://instruct1.cit.cornell.edu/courses/bionb424/students/gjs23/motionparallax.html
7. it is because of its distance..