The History of Calculus

Isaac Newton was the first to combine celestial and terrestrial gravity. He realized that there was a single attractive force between massive objects, not two separate types of forces. In combination with that he realized in combination with that, that gravity is also proportional to the masses of the objects involved. Once you understand those two ideas, that the force of gravitational attraction is proportional to the other words, the moon has less than the earth but it's stronger than the sun. You can just nearly perfectly describe the orbits of all the planets and their moons - even though they look totally different.