The force of gravity holds the Earth and the Moon in their orbits and our feet on the ground. The physical law behind it that Isaac Newton came up with is almost deceptively simple. Still, it governs the entire universe. But is it actually a force?
Here is how it all works: Newton’s Law of Universal Gravitation (PDF, 22 pages)
Featured image: ‘Earthrise’, taken by astronaut Bill Anders on 24 December 1968 during the Apollo 8 mission, the first spaceflight that reached lunar orbit. Public domain.
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