Astronomers have discovered six planets orbiting a bright, nearby star in perfect synchrony like a grand cosmic orchestra. The rare find can help explain how solar systems across the Milky Way galaxy came to be. Scientists made the announcement on Wednesday. A pair of planet-hunting satellites by NASA and the European Space Agency teamed up for the observations. The planets are two to three times the size of Earth, but made mostly of gas. None of the planets are within the star’s so-called habitable zone.