PINPOINTING the stable ways in which three planets or stars can waltz around each other has long been a perplexing problem. Now two mathematicians have proved the possibility of a new dance, in which the stars chase each other around a figure of eight.
Newton’s equations of motion can easily be solved to describe exactly how two bodies orbit each other. But if you throw in a third mass, the picture becomes hugely complex and it’s impossible to calculate all the possible periodic orbits directly.
Scientists in the 16th and 17th centuries found some simple solutions. For instance, Swiss mathematician…
