An ephemeris is a table or data file that provides the positions of celestial objects in the sky at specific times. It is commonly used in astronomy and navigation to predict the locations of planets, moons, and stars. The information is usually presented in a format that includes coordinates, such as right ascension and declination, which help astronomers locate these objects. Ephemerides are essential for various applications, including astrophysics, satellite tracking, and space missions. They can be generated for different time intervals, ranging from daily to yearly, and are crucial for understanding the movements of objects like comets and asteroids in our solar system.