Earth’s orbit is slightly elliptical, causing perihelion and aphelion variations. Combined with axial tilt and precession, this drives Milankovitch cycles influencing ice ages.
Understanding orbital eccentricity is key for climate modeling.
It provides context for studying habitable zones on exoplanets.
Earth moves about 3 million miles closer to the Sun at perihelion than aphelion.
[National Geographic, nationalgeographic.com]