lagrange-points

Lagrange's 1788 Mécanique analytique reformulated Newton using pure algebra. He discovered Lagrange points, invented calculus of variations, and survived the Revolution that killed Lavoisier.

There are five special spots in every two-body gravitational system where a smaller object can park itself and stay put. Here is the math, the missions, and the cosmic hitchhikers that have been using these parking spots for billions of years.