The planets in the solar system revolve around the sun in elliptical or nearly circular orbits. The variation between the closest and farthest points of planets that follow a ring-shaped orbit is less significant compared to the perihelion and aphelion distances of planets with elliptical orbits. The shape of a planet's orbit is measured in terms of eccentricity, where zero eccentricity corresponds to a perfectly circular orbit.
Earth's eccentricity is 0.017 and its perihelion distance is approximately 91 million miles from the sun, while its aphelion distance is around 95 million miles. The dwarf planet Pluto, meanwhile, has an eccentricity of 0.248. Its closest point to the sun is about 2.76 billion miles while its farthest point is around 4.64 billion miles.Learn more about Planets