Astronomers have discovered three new moons of Neptune, boosting the number of known satellites of the gas giant to 11. These moons are the first to be discovered orbiting Neptune since the Voyager II flyby in 1989, and the first discovered from a ground-based telescope since 1949. It now appears that each member of the giant planet’s irregular satellite population is the result of an ancient collision between a former moon and a passing comet or asteroid. “These collisional encounters result in the ejection of parts of the original parent moon and the production of families of satellites. Those families are exactly what we’re finding,” said JJ Kavelaars of the National Research Council of Canada, one of the team leaders along with Matthew Holman of the Harvard-Smithsonian Center for Astrophysics.