Here's why:

* Gravity: The sun is the most massive object in our solar system. Its immense gravity holds all the planets in orbit around it.

* Center of Mass: The planets do exert a gravitational pull on the sun, but it's much smaller than the sun's pull on them. The entire solar system actually orbits around a point called the center of mass, which is very close to the sun's center because of its immense size.

* Kepler's Laws: Johannes Kepler's laws of planetary motion describe how planets move in elliptical orbits around the sun.

In summary: The sun is the dominant gravitational force in our solar system. The planets revolve around the sun, not the other way around.