The shape of a planet's orbit is one of its fundamental properties, along with its size and distance from its host star.

Planets change orbit shape around Neptune’s size. Metal-rich stars help giant planets form. Eccentric orbits suggest chaotic planet formation.

How does a planet’s size influence its orbit around its parent star? This is what a recent study published in the Proceedings of the National Academy | Space ...

Earth has a nearly circular orbit, but some planets outside our solar system, called exoplanets, have very elliptical orbits ... data collected by NASA’s Kepler telescope, which monitored ...

Kepler showed that a planet swept out an equal geometric area of its orbit over the same length of time, no matter where in its elliptical orbit it might be, nor how eccentric that ellipse.