Since the 1950s, governments, companies, and researchers have been planting flags among the stars. But while it might seem like there’s plenty of room in space, some pieces of celestial real estate are more valuable than others. As far as human space exploration is concerned, Lagrange points may be the most important places in our solar system. So what exactly are they? Fabio Pacucci explains. Lesson by Fabio Pacucci, directed by Tim Rauch.