Our first attempt to organize a Symposium on solar activity was made at the lAO General Assembly in Brighton 1970. There, at the session of Commission 10, we proposed to organize a Symposium which would stress the observational aspects of solar activity. It was our hope that such a Symposium might stimulate studies of those important problems in solar physics which for a long time had been neglected in overall scientific discussion. Although a provisional date for the Symposium was then decided, it did not take place to avoid overlapping with other lAO activities. At the session of Commission 10 in Sydney -on the occasion of the XVth lAO General Assembly in 1973 -we repeated our proposal and forwarded the invitation of the Czechoslovak Academy of Sciences to organize the Symposium in Prague. Both were accepted. During the discussions about the programme of the Symposium -enthusiastically promoted by the late president of Commission 10, Prof. K. O. Kiepenheuer -it was decided to change slightly its subject. The theoreti cal problems were stressed and the majority of the Scientific Organizing Committee agreed not to deal with short-lived phenomena of the solar activity or with individual active regions. Symposium No. 71 was held in Prague from August 25 to August 29, 1975. Its Organizing Committee consisted of V. Bumba (Chairman), W. Deinzer, R. G. Giovanelli, R. Howard, K. O. Kiepenheuer, M. Kopecky, T. Krause, M. Kuperus, G.
The Moon is at once a face with a thousand expressions and the archetypal planet. Throughout history it has been gazed upon by people of every culture in every walk of life. From early perceptions of the Moon as an abode of divine forces, humanity has in turn accepted the mathematized Moon of the Greeks, the naturalistic lunar portrait of Jan van Eyck, and the telescopic view of Galileo. Scott Montgomery has produced a richly detailed analysis of how the Moon has been visualized in Western culture through the ages, revealing the faces it has presented to philosophers, writers, artists, and scientists for nearly three millennia. To do this, he has drawn on a wide array of sources that illustrate mankind's changing concept of the nature and significance of heavenly bodies from classical antiquity to the dawn of modern science. Montgomery especially focuses on the seventeenth century, when the Moon was first mapped and its features named. From literary explorations such as Francis Godwin's Man in the Moone and Cyrano de Bergerac's L'autre monde to Michael Van Langren's textual lunar map and Giambattista Riccioli's Almagestum novum, he shows how Renaissance man was moved by the lunar orb, how he battled to claim its surface, and how he in turn elevated the Moon to a new level in human awareness. The effect on human imagination has been cumulative: our idea of the Moon, and therefore the planets, is multilayered and complex, having been enriched by associations played out in increasingly complicated harmonies over time. We have shifted the way we think about the lunar face from a "perfect" body to an earthlike one, with corresponding changes in verbal and visual expression. Ultimately, Montgomery suggests, our concept of the Moon has never wandered too far from the world we know best—the Earth itself. And when we finally establish lunar bases and take up some form of residence on the Moon's surface, we will not be conquering a New World, fresh and mostly unknown, but a much older one, ripe with history.
The Sun is nowadays observed using di?erent techniques that provide an almost instantaneous 3-D map of its structure. Of particular interest is the studyofthevariabilityinthesolaroutputproducedbythedissipationofm- netic energy on di?erent spatial and temporal scales – the so-called magnetic activity. The 11-year cycle is the main feature describing this phenomenon. Apart from its intrinsic scienti?c interest, this topic is worth studying because of the interaction of such processes with the terrestrial environment. A ?eet of space and ground-based observatories are currently monitoring the behaviour of our star on a daily basis. However, solar activity varies not only on this decadal time-scale, as has been attested mainly through two methods: (a) records of the number of sunspots observed on the solar surface from 1610, and (b) the records of 14 10 cosmogenic isotopes, such as Cand Be, measured in tree-rings and i- cores, respectively. The study of the long-term behaviour of solar activity may be comp- mented by the study of historical accounts describing phenomena directly or indirectly related to solar activity. Numerous scienti?c and non-scienti?c d- uments have reported these events and we can make use of them as a proxy of solar activity in past times.