Cahill Rooftop Observatory

The Galilean eyepiece has only one purpose: to impress viewers with Galileo's patience and perseverance. This eyepiece uses the same primitive optical system Galileo used 400 years ago. Unlike modern eyepieces, the Galilean eyepiece has literally no eye relief – the amount of sky you see is always limited by how close you can get your eye to the barrel. No matter how close you place your eye, however, you'll still see only a tiny patch of sky. Pick this eyepiece as a challenge, or stick to the matching Plössl eyepiece instead.