The history of the transit of Venus and its observers is well documented. Just go through the ‘Past transits’ menu at the top of this page, which will take you on an interesting voyage through time. Of all the historical observations of the transit of Venus, an important group of observers usually doesn’t get much attention: the Jesuits. These Roman Catholic priests of the religious order Societas Iesu had a keen interest in mathematics, astronomy and natural sciences as a result of their apostolic spirituality. In their educational and missionary activities scientific work had an important place, because of their frontier spirit and their vocation to “find God in all things”. At their schools, colleges and universities they often established an astronomical observatory to study the universe and make meteorological observations. At the time of the eighteenth century transits of Venus (1761 and 1769) a quarter of all observatories was run by Jesuits and half of all clerics working on science were Jesuits. In their scientific work as well as apostolate they show how faith and reason harmonise well and are just the two sides of the same medal: the search for Truth.

Among the more well-known Jesuit observers of the transit of Venus are Maximilian Hell, Leonardo Ximenes and Joseph Xavier Liesganig. The Jesuits observed the transit from their colleges on the European mainland and rarely undertook expeditions. Maximilian Hell is one of the few Jesuits who travelled in the eighteenth century specifically to see the transit in its entirety (remarkably, on the invitation of the protestant king Christian VII of Denmark and Norway). Still, among the reports of observations from far flung places are also accounts written by Jesuits. They operated from the observatories in mission countries, where the Jesuit order had established missions to spread both the Christian faith and western science. The Imperial Observatory of Beijing for example was run by Jesuits, but the transit of Venus was also observed from other missionaries in Asia, like Tranquebar and Madras.

In between the two eighteenth century transits, the Jesuit order was suppressed for political reasons in Portugal, France, the Two Sicilies, Parma and the Spanish Empire. A couple of years after the transits, in 1773, the society was suppressed altogether by Pope Clement XIV under secular pressure. This ended all observatories, although some of the priests continued their work in the now nationalised institutions.

On June 5 and 6, 2012 the planet Venus will pass in front of the Sun for the last time this century. Millions around the world will witness this rare astronomical phenomenon.

In 1814 the Society of Jesus was restored, and the number of new observatories was again on the rise, especially in mission countries. They pioneered in systematically making astronomical, meteorological and seismological observations in Africa, Asia and Central and South America. Among the observers of the 1874 and 1882 transit of Venus are again many Jesuits, with prominent names like Stephen Perry and Pietro Secchi who both joined national expeditions.

The science versus religion controversy was instrumental in the foundation of Jesuit observatories in the nineteenth century, and it also played an important role in their closing in the twentieth century. After the 1960s, the priorities of the Society of Jesus moved toward work for faith and social justice. As a result, practically all Jesuit observatories have been closed in the last forty years and only a handful is still in operation today. Still, we owe a lot to the Jesuit scientists of the past, who with an apostolic zeal helped western science spread the world, and who made some valuable contributions in the study of the transit of Venus.