A study of 909 exoplanets in 355 multi-planet systems discovered by NASA’s Kepler Space Telescope reveals that, unlike our Solar System, other planetary systems are distinguished by strict regularity. This illustration shows the TRAPPIST-1 multi-planet system. Image credit: NASA / JPL-Caltech. Université de Montréal astrophysicist Lauren Weiss and co-authors used W. M. Keck Observatory in Hawaii to obtain high-resolution spectra of the Kepler...
