Here's why:

* The Sun isn't stationary: The Sun itself is not a stationary object. It's constantly moving, and its motion is influenced by the gravitational pull of all the planets in the solar system.

* Center of mass: The planets and the Sun revolve around a common center of mass. This point, called the barycenter, is the average location of all the mass in the system.

* Barycenter location: The barycenter is usually within the Sun because the Sun is so massive. However, the barycenter can sometimes be located outside the Sun's surface, particularly when large planets like Jupiter and Saturn are aligned.

Imagine a seesaw: If you have a heavy adult on one side and a small child on the other, the fulcrum (the point of balance) will be closer to the adult. The same principle applies to the Sun and planets.

Visualizing it: Think of the Sun as a heavy bowling ball and the planets as much smaller marbles. As the marbles orbit the bowling ball, they actually tug on it slightly, causing the bowling ball to wobble. The barycenter is the point where the bowling ball would balance if it were suspended in space.

In essence, the Sun and the planets all orbit their common center of mass, and the barycenter is not always located at the center of the Sun.