Celestial Navigation for Mariners As Fienberg explains, astronomers aren't the only ones who employ celestial coordinates. "Anyone who navigates by the stars uses them too," he says. "Even though all modern ships and boats have GPS systems onboard, sailors and other mariners are required to learn celestial navigation in case the GPS fails. If you can see Polaris, i.e., the North Star, you'll know which way is north — and, by extension, which ways are south, east, and west too. You'll also know your latitude, as the altitude of Polaris above the horizon is equal to your latitude. And if you have an accurate clock, you can also find your longitude by consulting a table of which stars are due south at the time you're observing." … [Read more...] about How Do We Find Things in the Blackness of Space?