While the idea of gravity was understood before, it was Sir Isaac Newton who mathematically explained gravitational force in his book "Philosophiæ Naturalis Principia Mathematica" (Mathematical Principles of Natural Philosophy) published in 1687.

Here's what Newton did:

* Defined the Law of Universal Gravitation: This law states that every particle in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

* Developed the Mathematical Formula: Newton derived a mathematical formula to calculate the force of gravity between two objects:

```

F = G * (m1 * m2) / r^2

```

Where:

* F is the force of gravity

* G is the gravitational constant (approximately 6.674 × 10^-11 m^3 kg^-1 s^-2)

* m1 and m2 are the masses of the two objects

* r is the distance between their centers

Newton's work revolutionized our understanding of gravity and its influence on the universe. It explained the motion of planets, the tides, and the fall of objects on Earth.

It's important to note that Albert Einstein later provided a more complete understanding of gravity with his theory of General Relativity, which treats gravity as a curvature of spacetime caused by mass and energy. However, Newton's law of universal gravitation remains a powerful tool for understanding many gravitational phenomena.