why does the iss move through the sky really quickly yet planets further out barely seem to move?

Question

why does the iss move through the sky really quickly yet planets further out barely seem to move?

In: Physics

Answer 1

It’s like driving down the highway and you see trees and poles adjacent to the road zip by but the mountains in the distance appear to move much slower. The viewing angle of closer things quickly changes whereas the viewing angle at distant things changes much slower. Likewise, the ISS is many orders of magnitude closer to Earth’s surface than planets, so while the ISS flies by, planets traverse the sky much more slowly.