Parallax is the apparent shift in position of an object when viewed from different angles or positions. This phenomenon is often used in astronomy to measure distances to nearby stars by observing their slight change in position relative to more distant stars as the Earth moves around the Sun.
The apparent motion of an object can vary depending on the motion of the observer. This is due to the concept of relative motion, where the perception of an object's movement is influenced by the observer's own motion. For example, if the observer is moving towards an object, the object may appear to move faster than if the observer is stationary.
The apparent motion of an object depends on both the observer's perspective and the motion of the object itself. As the observer moves, their angle of view and distance from the object change, altering how the object appears to move relative to them. In addition, the speed and direction of the object's actual motion will impact how it appears to move to the observer.
when position of the body with respect to an observer change with time then the body are said to be in motion.
An observer uses a frame of reference to detect motion because motion is relative and depends on the observer's point of view. By using a frame of reference, the observer can establish a stationary point against which to measure an object's position and velocity. This helps in determining whether an object is in motion or at rest relative to the observer.
One example is the Doppler effect, where the frequency of waves (such as sound or light) appears higher if the observer is moving toward the source and lower if moving away. Another example is parallax, where the position of nearby objects appears to shift relative to distant objects when viewed from different locations.
The apparent motion of an object can vary depending on the motion of the observer. This is due to the concept of relative motion, where the perception of an object's movement is influenced by the observer's own motion. For example, if the observer is moving towards an object, the object may appear to move faster than if the observer is stationary.
Parallax, more accurately motion parallax, is the change of angular position of two observations of a single object relative to each other as seen by an observer, caused by the motion of the observer. Simply put, it is the apparent shift of an object against a fixed background that is caused by a change in the observer's position.
The apparent motion of an object depends on both the observer's perspective and the motion of the object itself. As the observer moves, their angle of view and distance from the object change, altering how the object appears to move relative to them. In addition, the speed and direction of the object's actual motion will impact how it appears to move to the observer.
when position of the body with respect to an observer change with time then the body are said to be in motion.
With respect to a state of rest or apparent rest.
The term you're looking for is "parallax." Just a caution for you not to confuse parallax, which does answer your question, with the retrograde motion of some of the planets, which is related but different.
Motion
Observer.
Polaris does not appear to move.
An observer uses a frame of reference to detect motion because motion is relative and depends on the observer's point of view. By using a frame of reference, the observer can establish a stationary point against which to measure an object's position and velocity. This helps in determining whether an object is in motion or at rest relative to the observer.
One example is the Doppler effect, where the frequency of waves (such as sound or light) appears higher if the observer is moving toward the source and lower if moving away. Another example is parallax, where the position of nearby objects appears to shift relative to distant objects when viewed from different locations.
The location of an observer of motion is typically described in terms of a reference frame. This frame can be stationary or in motion itself, and serves as a point of reference to describe the position and movement of objects. Observers can be located at any point within this reference frame to study the motion of other objects relative to their own position.