I know I sound very dumb asking this but I am still confused at how the moon moves across the sky at night. I just don’t understand how it works, is it perception? The way the sun reflects light off the moon? I know the moon orbits around the earth every 28 days but it makes no sense to me. Many thanks.
In: Physics
The moon moves across the sky primary for the same reason the sun and the stars move across the sky. Earth is rotating around its axis.
Only something directly above the north or south pole is stationary. So Polaris that is very close to that point is almost stationary.
Stuff in any other direction will move circles. The size of the circle depends on where relative to the earth axis and the moon is close to directly over the equator.
The orbit of the moon around the earth will have an effect so the moon moves at a sight different rate than the stars.
If the moon orbited the earth once per day it would be stationary.
You can compare it to you sitting on a chair that can spin around. Sit on it and spin at a constant rate and the room around you will move like the start. Have a friend walk around you in a circle once for 28 rotations of the char. That will be the motion of the moon.
IF you then look it is quite clear that most of the motion each day is because you spin but some is because of the moment of the moon.
The moon moves around earth one per 27.322 days relative to the star so an angular movement of 360/27.322= 13.17 degrees per day. The moon’s actual size is 0.5 degrees so it will move 13.17/0.5=26.35 times its own per day. That is its own width in 54 minutes.
Latest Answers