Newton's Law of Gravity
Isaac Newton formulated the universal law of gravitation
July 05, 1687
Newton and the Falling Apple
The story of Isaac Newton and the falling apple is one of the most famous in science. Around 1666, while staying at his family home in Lincolnshire to escape an outbreak of plague at Cambridge University, Newton observed an apple falling from a tree. The exact details are probably embellished — Newton himself mentioned the apple in later life, but accounts differ. What is certain is that during this period, Newton began developing the mathematical framework for his law of universal gravitation, though he would not publish it for another twenty years.
What the Law States
Newton's law of universal gravitation, published in his landmark work "Principia Mathematica" in 1687, states that every object in the universe attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of the distance between them. In plain language: heavier objects pull harder, and objects farther apart pull less strongly. This single law explained why planets orbit the sun, why the moon orbits the Earth, and why objects fall toward the ground.
A Foundation for Modern Science
Newton's gravitational law was the first unified mathematical description of a natural force, and it held up with extraordinary precision for over 200 years until Einstein's general theory of relativity provided a deeper explanation in 1915. Even today, Newton's equations are used for most practical calculations — from launching satellites to landing spacecraft on Mars. The Principia is widely considered the most important scientific book ever written. Use our age calculator starting from 1687 to appreciate how long Newton's law has shaped science.