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How did Isaac Newton connect a falling apple with the Moon’s orbit?

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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.

Isaac Newton connected the falling of an apple to the Moon’s orbit by proposing that the same gravitational force acting on objects at Earth’s surface also governs the motion of celestial bodies.12

To demonstrate this, Newton compared the distance a body falls on Earth in one second to the distance the Moon is diverted from a straight-line path in its orbit during the same time. He knew the Moon’s distance from Earth is approximately 60 times Earth’s radius. By applying his laws of motion, he calculated that the Moon’s inward acceleration is $1 / 60^{2}$ (or 1/3,600) of the acceleration of an object falling near Earth’s surface.23

This numerical correlation confirmed that gravity follows an inverse square law, meaning the force weakens as the square of the distance increases. By synthesizing these observations, Newton established that gravity is a universal force acting between all massive objects, effectively bridging the gap between terrestrial physics and the mechanics of the universe.4231