Gravity Lab

A sandbox universe running real Newtonian gravity. Drag to launch a planet and watch the orbit you are about to make before you let go, then bend the law itself — turn gravity off, make it fall off as 1/r³, add dark matter, or switch on Einstein and watch an orbit precess. 18 missions, 17 illustrated articles and quizzes where every question asks you to read a graph, a diagram or your own solar system.