Today, I want to talk about the equatorial coordinate system. Start with this: What if we could project Earth’s coordinates of longitude and latitude into the sky? Latitude wouldn’t be a problem, but ...

How much of the sky can you see at any one time? This, of course, assumes you are looking up from a wide-open, flat field or out on an ocean liner with nothing but a flat horizon no matter which way ...

Since antiquity, the sky has been thought of as a bowl, or celestial sphere, that's directly overhead. The equatorial coordinate system that astronomers use to find stars and other objects is based on ...