Here's why:

* Gravity: All objects with mass have gravity, but the strength of gravity depends on the object's mass. Larger objects have stronger gravitational pulls.

* Stars are massive: Stars are incredibly large and massive celestial bodies. Their immense mass creates a powerful gravitational field that attracts surrounding matter.

* Planets orbiting stars: The planets in our solar system are held in orbit around the Sun due to its immense gravity.

Let me know if you'd like to know more about stars or gravity!