Celestial coordinate systems are frameworks used by astronomers to pinpoint the locations of celestial objects in the sky. The most common system is the equatorial coordinate system, which uses two main coordinates: right ascension and declination. Right ascension is similar to longitude on Earth, while declination is akin to latitude, allowing for precise mapping of stars and planets. Another important system is the horizontal coordinate system, which is based on an observer's local horizon. It uses altitude and azimuth to describe the position of celestial objects. Altitude measures how high an object is above the horizon, while azimuth indicates the direction along the horizon.