Ephemerides and calendars :

The usefulness of positional astronomy ?

The observation and study of the bodies of the solar system bring us knowledge on our space environment, on neighbouring planets but have other interests larger that the only exploration of solar system. For example, the observation of the Sun brought us the knowledge of the nuclear energy. The observation of motions in the solar system brought us the understanding of some fundamentals:
- the theory of general relativity received confirmation through the motion of Mercury which was not described by the only newton's theory of gravitation;
- celestial mechanics was the basis of the launch of artificial satellites usefull for the observation of the Earth, telecommunications, meteorology,...
- the study of the long term evolution of the solar system told us about the changes in the climate on the Earth.

besides this essential knowledge, the astronomical calculations of positions have a closer interest for us: it is the determination of the motion of the Sun which orders everyday life on Earth. With the motion of the Moon, they are the basis of calendars. Hours of sunrises and sunsets are useful for many purposes.
We provide ephemerides in the next pages: positions of solar system bodies, rises and sets for any place, dates of astronomical phenomena such as eclipses and many information on the different calendars still in use.
We propose also detailed explanations on these topics.