Circular orbit | astronomy | Britannica

The detailed behaviour of real orbits is the concern of celestial mechanics (see the article celestial mechanics). This section treats only the idealized, uniform circular orbit of a planet such as Earth about a central body such as the Sun. In fact, Earth’s…

The process from capture to circular orbit may have taken more than one billion years, during which time the enormous tidal deformations experienced by Triton most likely melted its entire interior. The molten body would have undergone differentiation, the denser material sinking into a core region and the more-volatile materials…