When Galileo first pointed his telescope to the sky 400 years ago, the number of previously unseen stars this piece of equipment brought to light astounded him. In Sidereus Nuncius (“Starry Messenger,” published in 1610), he wrote: “In addition to stars of the sixth magnitude, a host of other stars are perceived through the telescope which escape the naked eye.” He realized that they far exceed in number the stars visible to the unaided eye.
