Why does it feel as if the Moon is following us wherever we go?
When you travel by train, the houses and trees outside seem to be rushing backwards. However, no matter how fast you travel, the Moon and the stars do not rush backwards, but seems to move along with you. Why is this?
When things are near us, we move past them very quickly. After that, we don’t see them any more. That is why trees and houses seem to rush past at great speed.
Suppose you’re in a car, and you’re looking out the window. You see lots of motion in the landscape as you pass trees, buildings, and signs. Let’s say you’re driving by a house. First you see it in front of the car, then to the side of the car – then it’s behind you.
image source: wikimedia commons
That’s how your visual system knows that you’re moving by the house.
But, when things are far away, we’ll see them for a longer period, since it takes a longer time to go past them. This explains why distant objects like mountains don’t seem to rush past the window of a moving train.
As we know, the Moon is very, very far from us. That is 3,84,400 kilometers away. Because of its great distance, the angle at which we view the Moon changes very little as we move.
Even if we travel 200 km/hr, it remains in relatively the same position in the sky. So, wherever you go, the Moon appears to be in the same position, almost as though it is following you.