The planets orbit the sun in an elliptical shape due to the gravitational force between the sun and the planets. According to Kepler's laws of planetary motion, planets move in elliptical orbits with the sun at one of the foci. This means that the gravitational force between the sun and the planets causes the planets to move in elliptical paths rather than circular ones. The shape of the orbit is determined by the balance between the gravitational pull of the sun and the planet's forward momentum.
