Britannica Sources used in this answer

Why is Newton’s law of gravity still useful for most calculations?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

gravitational lens — gravity A galactic cluster, about five billion light-years away, produces a tremendous gravitational field that “bends” light around it. This lens produces multiple copies of a blue galaxy about twice as distant. Four images are visible in a circle surrounding the lens; a fifth is visible near the center of the picture, which was taken by the Hubble Space Telescope.

Newton’s law of gravitation remains highly useful for most calculations because it provides valid, accurate results for objects moving at speeds much slower than the speed of light.1

While Albert Einstein’s theory of general relativity offers a more complete and precise description of gravity—accounting for phenomena like the precession of Mercury’s orbit that Newtonian physics cannot fully explain—it is mathematically more complex. For the vast majority of practical applications, including describing the motions of bodies within our solar system, the differences between Newtonian predictions and relativistic ones are negligible.1234

Newtonian gravity is essentially an excellent approximation for low-velocity, weak-field environments. Because it is simpler to apply and yields results that are consistent with observation to a high degree of accuracy in these contexts, it remains a fundamental tool in classical mechanics.123