Until recently, the most powerful telescopes have been huge light-reflecting mirrors. But scientists now have a new way of looking at the sky: the Dragonfly Telephoto Array, co-designed by Yale’s Pieter van Dokkum using the latest advances in optics, sensors and control systems. The Dragonfly has already discovered a new class of ghostly galaxies, and astronomers hope it will soon be able to detect the elusive "cosmic web," the dark matter connecting all galaxies in the cosmos.