ABSTRACT
The position of any celestial body within the Solar system can be determined in two coordinate systems – ecliptic and equatorial. Observations from the Earth usually give the coordinates of a celestial body with respect to the plane of the equator. The ephemerides should be composed in the Earth’s system of coordinates, or more definitely, in the geocentric equatorial system, though one can determine the position of a celestial body with respect to the heliocentric ecliptic system as well. Evidently the problem is the representation of the coordinates of the celestial body in a system convenient for the observer on the Earth, namely, in the form of right ascension, declination and the distance from the Earth. The chapter focuses on this problem, so the main considerations and final results are equally true for all three types of orbits – elliptic, parabolic and hyperbolic.
