The force that keeps planets in orbit around the sun is gravity. Gravity is a fundamental force of nature that attracts two bodies toward each other. In the context of the solar system, the sun's massive gravitational pull acts on the planets, pulling them toward it. The balance between this gravitational attraction and the inertial force resulting from the planets’ motion keeps them in stable orbits. The laws of planetary motion, formulated by Kepler, describe how planets orbit elliptically, while Newton's law of universal gravitation provides the framework to understand why objects, including planets, move under the influence of gravity.