Apsidal precession
（重定向自Perihelion precession）
![Planets revolving the Sun follow elliptical (oval) orbits that rotate gradually over time (apsidal precession). The eccentricity of this ellipse and the precession rate of the orbit are exaggerated for visualization. Most orbits in the Solar System have a much smaller eccentricity and precess at a much slower rate, making them nearly circular and stationary.](/Images/godic/202502/02/Precessing_Kepler_orbit_280frames_e0.6_smaller3012.gif")
![The orbital parameters. The line of apsides is shown in blue, and denoted by ω. The apsidal precession is the rate of change of ω through time (dω/dt).](/Images/godic/202502/02/Orbit1.svg3012.png")
![change in orbit over time](/Images/godic/202502/02/Perihelion_precession.svg3012.png")
![Effects of apsidal precession on the seasons](/Images/godic/202502/02/Precession_and_seasons.svg3013.png")
In celestial mechanics, perihelion precession, apsidal precession or orbital precession is the precession (rotation) of the orbit of a celestial body. More precisely, it is the gradual rotation of the line joining the apsides of an orbit, which are the points of closest and farthest approach. Perihelion is the closest point to the Sun. The apsidal precession is the first derivative of the argument of periapsis, one of the six primary orbital elements of an orbit.