Its position.
An object that is changing positions is in motion.
it is motion
motion
If an object is in motion than its position is changing.
Motion
An object is in motion only if its distance from a reference point is changing. The average speed of the object is given by the object's rate of change of displacement from the reference point over time.
The rate at which the speed or direction of its motion is changing.
Direction
The rate at which the speed or direction of its motion is changing.
when A is in motion with respect to B, then B is in motion with respect to A note: A and B are bodies or anything
it depends on the reference points, that is form where the object is viewed...when sun is viewed form earth, it moving...but earth is also moving...when the rotation of the earth is stopped, then the sun is at a constant position...thereforean object position relative to another object is changingonly when the reference point changes..
The light hits its own motion to make its speed