It's a system that's been around since ancient times. "The idea of celestial coordinates does assume that the sky is a sphere that surrounds the Earth. This is the idea that traces back to the early belief that the Earth was the center of everything," Christopher Palma, a teaching professor and associate head for undergraduate programs in the Department of Astronomy and Physics at the Pennsylvania State University, says in an email. "Even though we now know that to not be true, it is still true that the sky appears to be a sphere surrounding us, so we can use spherical coordinates to identify any location on the sky." … [Read more...] about How Do We Find Things in the Blackness of Space?