Here's why:

* The Sun is not stationary in the universe: The Sun orbits the center of our Milky Way galaxy, taking about 225-250 million years to complete one orbit. It also moves relative to other stars in our local neighborhood.

* The Sun is the center of our solar system: This means the Earth and the other planets orbit around the Sun. From our perspective on Earth, it appears as if the Sun is stationary while we move around it. This is what we used to believe for a long time.

Therefore, it's more accurate to say:

* The Sun is not stationary in the absolute sense. It moves within the galaxy.

* The Sun is the center of our solar system, and it appears stationary from our perspective on Earth.

Let me know if you have any other questions!