The most common real-life example of an ellipse is the orbiting path of a planet. Most orbits are not circular in nature, and they are often most similar to an oval in shape.
According to Purplemath, one good example of an ellipse is the orbit of Pluto. Pluto does not have a perfectly round orbit, and that means that its orbit is elliptical in nature. Ellipses can also take place on Earth, but it's most common to see elliptical examples in space. For instance, Halley's comet has an elliptical orbit that allows the comet to be seen from Earth only once every 76 years.
Mercury also has an elliptical orbit. Most of the orbits of the planets are ellipses, but the amount of the flattening of the ellipse is so small that they appear to have circular orbits. To determine that the planets are actually rotating on an elliptical orbit, a person must measure the geometry of that orbit carefully. The sun itself is the center of the planets' elliptical orbits.
Johannes Kepler's three laws are used to determine if objects are elliptical. His laws focus on the elliptical orbits of the planets, and they allow the future position of the planets to be predicted.