Two exoplanets share the same orbit

New Scientist : In the four-planet system KOI-730, two of the planets share the same orbit around their star. They circle their Sun-like parent star every 9.8 days at exactly the same orbital distance, one about 120 degrees ahead of the otherâmdash;called the gravitational “sweet spot.” The discovery bolsters the theory that our Moon was formed about 50 million years after the birth of the solar system, from the debris of a collision between a Mars-sized body and Earth.