Lunar theory
![Newton's diagram 'to find the force of the Sun to perturb the Moon' accompanying Book 3, Proposition 25 of the Principia](/Images/godic/202501/25/096-newt1687-figp4345414.jpg")
![Alternative depiction of solar perturbations, vectors LS1 and LS2, like LS in Newton's diagram above, for 2 positions of the Moon P in its orbit around the Earth S](/Images/godic/202501/25/09a-2moonperts5414.jpg")
![Solar perturbation vectors (arrows) analogous to LS at many positions of the Moon in its orbit around the Earth](/Images/godic/202501/25/Field_tidal.svg5414.png")
![The Laser Ranging Facility at Goddard Spaceflight Center](/Images/godic/202501/25/Goddard_Spaceflight_Center_Laser_Ranging_Facility5414.jpg")
Lunar theory attempts to account for the motions of the Moon. There are many irregularities (or perturbations) in the Moon's motion, and many attempts have been made to account for them. After centuries of being problematic, lunar motion is now modeled to a very high degree of accuracy (see section Modern developments).