This text stems from the first part of a paper I gave at the 260th symposium of the International Astronomical Union (IAU) and published electronically in "The Role of Astronomy in Society and Culture", Proceedings of the International Astronomical Union, IAU Symposium, Volume 260, p. E16.


There are two nineteenth century clocks in my house. The time ticks in the rhythm of a pendulum which length varies as a function of the temperature and humidity of the air (a section of the pendulum is in textile). As the length varies the pendulum frequency changes and with it the clock hands move faster or slower. The differences amount to few minutes per week. I, therefore, have to adjust the clocks every week or so. This I do using the time given by my computer which reflects to a high precision the local legal time. Few decades ago, this adjustment was made using the time signal derived from observatories, in Switzerland, the observatoire chronométrique de Neuchâtel, and relayed by the radio. Before that, time was kept in every major city by local observatories, whose primary function this was.

Nowadays, we tend to see in astronomy an activity that is mainly, if not solely devoted to the understanding of the Universe and the objects to be found within. The short story above illustrates that this was very far from reality until few decades ago. Most of the astronomical workforce over history has been invested not so much in a cultural endeavour, but rather in a tedious quest for the measurement and keeping of time. Agriculture requires that seeds are planted well in advance of the season of growth. It is, therefore, necessary to know when to plant.  It is well known that weather is a very poor indicator of the seasons. The observation of the stars, the position of well known stars at the night onset for example, or the position of the Sun as it rises or sets are much better indicators of the progress of the year.  Since the Moon month and the year do not have a simple relation, the quest for timekeeping during the year is a complex one. Astronomers have, therefore, spent large efforts worldwide to solve this problem form the beginning of agriculture millennia ago onward.

The same is true for other needs of society that require(d) a precise knowledge of the heavenly sphere. Ocean travel  certainly requires seaworthy  ships, but it also requires the capacity to locate oneself on the surface of the Earth in unknown territories and on sea. This is provided by a precise knowledge of the respective positions of Sun, Moon, planets and stars, together with a good mastering of time keeping. All of this knowledge is based on astronomy.

The daily needs of human society also require some level of time keeping, be it only to be able to meet at given time and place. Here again the local timekeeping in many organised societies has relied on astronomical observations. The results being then relayed to the population by bells, canons and other signals.

It is interesting in this respect to look at the history of three observatories in the Jura regions in the middle of Europe, Geneva Besançon and Neuchâtel. The Geneva observatory was founded in 1772 on a small hill close to the city walls. It was primarily a time keeping service for the city. The duties of the observatory director included also keeping meteorological records. Observatory staff were busy until the 1960's with measuring the stability of clocks produced by the local manufactures. Teaching belonged to the responsibilities of the director as well as keeping up with the literature as a side activity. There was very little creation of knowledge until the middle of the 20th century. It is only from the 1950s and 1960s onward that astronomy as a science became the main purpose of the observatory.

The observatory of Neuchâtel ( was founded in 1858 and was part of the department of economic affairs. Its purpose was to use astronomical observations to calibrate clocks. In more recent years the observatory of Neuchâtel kept its function of time keeper and  turned to atomic clocks, a domain in which it became  very prominent. These activities moved to the University of Neuchâtel in 2008. The observatory is now used for public presentations and sky observations.

The founding of the observatory of Besançon ( was decided in France in 1878 with the explicit purpose of supporting the  watchmaking industry in the French Jura region and to give them tools to meet the competition of the Geneva and Neuchâtel watch manufactures.

In all these developments astronomy as an intellectual quest has little or no role. Similar histories can be found elsewhere in Europe and in the world. Take as a further example the Greenwich observatory which gave the time to the british fleet in the Thames river few hundred meters away by dropping a ball on its roof everyday at noon sharp. Astronomy as a science did develop in this frame, but the scientific part of the Greenwhich observatory moved around  in England during the 20th century and was dissolved in the 1990s in the rest of the british astronomical establishment. The Greenwhich observatory site is now turned into a museum.

Astronomy has thus been a most practical endeavour for most of the human history. While the discussion and the examples given above come from the western world, Chinese astronomy history tells us that similar developments took place elsewhere on the Earth as well. Everywhere also the spiritual or ritual aspects of the lives of societies have rested on astronomically determined epochs. As examples, Christmas is a Winter solstice feast, Easter and its declinations in different religions is a Spring equinox event and the Ramadan is precisely defined by the Moon month and Moon observability in a given location.   

The benefits of astronomy for society cannot be overestimated. Agriculture, navigation and the organisation of societies have depended crucially on astronomical observations for almost the whole of the history of human civilisations. The development of a "Weltbild" should be seen in this context as an, important, side benefit.

The practical importance of astronomy has only rather recently ceased to dominate the activities of astronomers. The observatory of Geneva, as one example, has been in charge of certifying chronometers for the local manufactures until  the late 1960's. And when I studied in Zurich in the 1970s astronomy teaching was still heavily dominated by positional astronomy and time determination.

While in the last several decades the discovery of astronomical objects and the understanding of the physics behind them has been the primary motivation of astronomical activities, the practical aspects related to this quest have not become negligible. Instruments have become very sophisticated to reach ever fainter objects, they have been placed in  remote locations on the Earth or in orbit to avoid the disturbance related to the atmosphere. These requirements have lead to the development of many technologies that spread to other domains of human activity, for example in medical imaging. Modern astronomy and space sciences have also served the political agendas of a number of countries or regions. Suffice it to mention the race to the Moon of the United States in the 1960s and the renewal of this effort by Chinese authorities now.

In some very fundamental aspects the development of a "weltbild", which one would certainly classify as a purely intellectual endeavor, has a profound practical side too. The Copernician revolution has moved the human beings from the centre of the Universe to a location as good as any other. This changed deeply not only our way of seeing ourselves in the world, but also our way to act on the Earth. A similarly deep revolution is taking place now. Observations in the X-ray domain of the electro-magnetic spectrum have shown that the timescale on which the cosmic environment evolves is not only billions of years, but can be as short as years, days or seconds. We are learning that our world is the seat of extraordinarily violent phenomena. It not so that beyond the orbit of the Moon reigns perfection and immobility on the human timescales. Had our forefathers known this, they would surely not have called the God of the ancient testament "the Eternal". How this revolution in our perception of cosmic reality will influence our actions in the coming centuries will be an interesting object of study, a long way beyond the present text.

 So contrary to the most common view of astronomy its practical aspects have dominated  for almost the whole human development. Although we remember only a few very impressive Greek, Arabic and Western Astronomers over history, we know that there was a host of other people who tirelessly scrutinised the sky to know the course of the years and that of the days.