Joseph-Louis Lagrange (1736–1813) was an Italian mathematician who developed some of the most important theories of mechanics, regarding both Earth and the universe. Generally remembered as a French scientist because he spent the last part of his career in Paris, his analysis of the wobble of the Moon about its axis of rotation won him an award from the Paris Academy of Sciences in 1764. Lagrange also worked on an overall description of the way that forces act on groups of moving and stationary objects, a project that Galileo Galilei and Isaac Newton had begun years before. He eventually succeeded in devising several key general mathematical tools to analyze such forces. These were published in a 1788 work called Mechanique Analytique (“Analytical Mechanics”). Lagrange went on to explore the interaction between objects in the solar system as a complex system of objects. He discovered what are called Lagrange points: places around and between two gravitationally bound bodies where a third object could stay stationary relative to the other two. This proves useful today for placing satellites in space.

In 1793, Lagrange was appointed to a commission on weights and measures, and helped create the modern metric system. He spent his final working years trying to develop new mathematical systems of calculus.