Here's why:
* Kepler's Laws of Planetary Motion: Johannes Kepler, a German astronomer, formulated three laws that describe planetary motion. His first law states that planets move in elliptical orbits with the sun at one focus of the ellipse.
* Gravitational Force: The sun's gravitational pull is strongest when a planet is closest to it and weakest when it's farthest away. This uneven force results in an elliptical path rather than a circular one.
While the orbits of planets are elliptical, they are often close to circular. For example, Earth's orbit is only slightly elliptical.
