This book provides the fundamental knowledge of ephemeris calculation. Starting from Kepler's laws, it calculates the coordinates of the planets in the orbital plane. Through a series of transformations, the coordinates in the horizontal system are determined, allowing for the angles to be set on a telescope to observe a specific planet. The two-body or Kepler problem is thoroughly explained, along with the calculation of additional parameters such as orbital speed and the distance of the planets from the Sun, illustrated with examples of individual planets. Additionally, going beyond the two-body problem, the calculation of the Moon's position is discussed. The main influences on the planetary orbits that were not considered in the two-body problem calculations are also explained.