While often depicted as perfect circles, planetary orbits are slightly oval-shaped. This means that the distance between a planet and the sun varies throughout the planet's orbit.

Here are some important points about elliptical orbits:

* The sun is at one focus of the ellipse. This means the sun is not at the exact center of the orbit, but slightly offset.

* The planet's speed varies throughout the orbit. It moves fastest when it is closest to the sun and slowest when it is furthest away.

* Kepler's laws of planetary motion describe the shape and properties of elliptical orbits.

It's important to remember that most orbits are nearly circular, meaning the ellipse is only slightly elongated. But understanding that they are truly elliptical helps to better grasp the intricacies of planetary motion.