A sextant is a tool for measuring the angles between heavenly bodies — the kind found in outer space. Used as a navigational tool out at sea, it helps determine a ship's longitude and latitude.
There is nothing sexy about a sextant, unless you're a sailor. Even then, in today's world of sophisticated instrumentation, it's considered quaint and old-fashioned. The noun sextant dates back to the late 16th century, from the Latin word sextans, meaning "sixth part." The sextant uses a graduated arc of 60° (there's the six reference) for measuring the altitude of the planets and stars.