How can you tell if an object is moving when its motion is too slow too see?

Answer 1

You have to use an accurate measure with fine divisions, and pick out a noticeable spot on the object to compare position over time. Measuring over a longer period of time is useful too, note down the position every minute or even longer intervals if necessary

Answer 2

The term "see" is very vague, but I will assume it means "see with the naked eye over a short period of time".

The easiest way to see long slow movements is historical markers. For example, the Columbia Ice Fields in Alberta, Canada have retreated 1500m over the last 260 years. This is equal to about 15.8mm per day. Over the years, signs have been placed up the mountainside showing the extent at that period.

For short-period slow movements, there are several different options, but one of the preferred methods is a series of force meters that can detect a change in pressure at a given point.

Answer 3

A reference point is a place or object used for comparison to determine if something is in motion.

Answer 4

To determine if an object moves w.r.t. an observer or reference point, measure its distance to the observer, then later measure the distance again and note whether it is the same.