It is not possible to sketch the history of astronomy by amateurs without first defining what the term “amateur astronomer” truly means. But we must avoid using “the benefit of hind-sight” to interpret the past in terms of a concept, the relevance of which has been perceived only during the course of the last one hundred years. In order to avoid the sophistry arising from such a purely imaginary history that is based on false conceptions, it is useful to examine amateur astronomy’s precise status, since its emergence in the dawn of classical science, by outlining the type of relationship that it has had with “professional” astronomy. In doing so, we can evoke some of the major developments in amateur astronomy, the scientific contributions of which, although often of high quality, have at times reached the very forefront of the discipline of astronomy.

Double stars are favourite objects for amateurs, who can see them with modest instruments and easily observe their eventual motion. Moreover, it is possible to calculate their orbits, and even masses, with no other equipment than a pencil, a piece of thread and two pins to draw the ellipses that these systems have been following for centuries.

Binary stars are part of those classes of objects whose geometrical structure remains the same at different scales, they are internally homothetic and represent a field to which fractal geometry may be applied. All this explains the popularity of these objects with amateurs: anyone is able to see some of them, whatever the power of their instruments.

Little distinction was drawn between amateur and professional astronomers for much of the nineteenth century. They mixed in the same scientific societies and often carried out overlapping studies. Towards the end of the century, however, new factors arose - increasing expense of instrumentation, increasing sophistication of theoretical knowledge, etc., which led to a greater degree of differentiation. It was then that societies specifically aimed at amateurs were established. The split has never been complete – professionals have always been members of amateur societies and vice versa - but a gap between amateur and professional opened up and has continued since. Amateurs of the standing of Percival Lowell, who could compete with professionals both in terms of equipment and theoretical knowledge, effectively died out before the mid-twentieth century.

While significant contributions of amateur astronomers are generally recognized in the literature, the identification of the individual as an amateur is frequently unclear. As a result, amateur astronomers today have a limited sense of the contributions of earlier amateur astronomers. In part, this problem stems from current usage of the word “amateurish” as a pejorative, representing something not well-done or lacking in quality. In addition, many individuals, who take pride in identifying themselves as amateur astronomers are neither inclined, nor in fact capable, of making a contribution to astronomy. It is important, however, for historians and others who write about the history of astronomy to recognize amateur astronomers and identify the significance of their contributions. For it is through such elaboration that other amateurs will recognize the possibilities and great value that may be associated with their own efforts. Therefore it is necessary to develop a common understanding of the characteristics that distinguish an amateur astronomer from what I identify in this paper as a “recreational sky observer”. Such a classification scheme should help future writers to correctly identify amateur astronomers and their contributions.

Amateur astronomers play an important role in historical astronomy and publish a wide range of studies. They can participate nearly as well as professional astronomers since neither are professional historians or archaeologists. Amateurs often restore old instruments and facilities, discovering clues to their design, manufacture and use that would not be noticed by non-astronomical historians.

Possible studies include histories of institutions and of astronomy in different countries, biographies, and evolution of ideas. Publications and manuscripts could be studied for matters of current and historical importance. Folklore (of all countries) should be recorded before it dies out, and the beliefs behind it examined. More study groups involving amateurs, professionals and others should be established.

In August 1957, the magistrate Charles Boyer, who was President of the Court of Appeal at Brazzaville in Africa and an amateur astronomer, began to photograph the planet Venus systematically, using a violet filter and his own personal telescope, 256-mm in diameter, with an optical window. His aim was to study the positions of the dark, changing markings that had been detected in ultraviolet light by Ross at Mount Wilson in 1924. He was collaborating with Henri Camichel at the Pic-du-Midi Observatory, who was simultaneously observing with a 60-cm reflector. Over 68 days’ observation, Charles Boyer noted a periodicity of 4 days in the appearance of the markings. Alerted by this, Henri Camichel found the same effect on his series of images. Charles Boyer photographically added together the images on plates obtained at daily, 3-day, 4-day, and 5-day intervals (1). The combination of different images cause the markings to disappear. Only superimposition of 4-day images revealed any detail, the result of periodicity in the planet’s appearance.

Probably no other branch of science has benefited as much from the work of dedicated amateurs as has the science of Astronomy. While some amateurs have made many useful types of astronomical observations– comets, meteors, occultations, etc. – perhaps none has been as extensive and as useful as those made in the field of variable stars. There are not nearly enough professional astronomers to keep under proper observation the increasingly large number of known variables. While all kinds of them are well worth continuous study, this paper will call attention to the importance of eclipsing variables and in particular the systematic and continuing observation of their times of minimum light.

Amateur astronomy in Poland has its own history dating from the 17th century to the present day. Before the 17th century, the term “amateur astronomer” loses its meaning. Otherwise we might pose the rather paradoxical question: “Was Copernicus an amateur?” and probably have to give the answer: “Yes, he was an amateur, being first a priest, a physician and a lawyer.” Let us leave him in peace and instead turn to more undoubted amateurs. The history can be divided into two general periods: before and after the creation of the Polish Amateur Astronomical Society, PA AS (Polskie Towarzystwo Milosników Astronomii – PTMA). Here we present 16 Polish amateur astronomers who contributed to astronomy from the 17th to the 20th centuries, except Jan Heweliusz – the greatest – who is discussed elsewhere (1). All are selected from a much larger group, the selection being made in accordance with the rules described in the very useful and practical “Criteria for identifying an astronomer as an amateur”, formulated by Tom Williams a few years ago and presented here (2). There is also a short history and current information about the PAAS. Finally, we summarize successes and failures of amateur astronomy in Poland and put some general questions about its future.

In 1926 Horace Dall commenced optical work, with interests covering both microscopes and telescopes. Soon (1928), he was making solid eyepieces of the Tolles type. Eventually he developed skills in making lenses of the smallest size to be incorporated into microscope objectives of the highest numerical aperture; this culminated in an objective with a N.A. of 1.92 (a record). The lenses were jewelled elements worked with diamond dust. During World War 2 he repaired all the microscope lenses damaged in the U.K. that had originated with the German firm of Leitz.

Horace Dall had an exceptionally inventive mind – and was so active in developing his ideas that he had insufficient time to formally write them up, hence much of his work remains unpublished. He did, however, keep extensive notebooks of his researches into optics. These, along with many prototypes, are now in the custody of the Science Museum, London. Combining his interests in travel, optics, and astronomy, Dall developed a number of portable, ultra-lightweight telescopes. He discovered that by incorporating what is in effect a long working distance, low-power microscope with a Cassegrain telescope he had an instrument with several advantages. The image was erect, the secondary small, and by use of a suitably placed internal stop, sky-flooding was eliminated without the use of shade tubes. Always looking for improvements in optical performance he hit on the idea of modifying the classical Cassegrain telescope by employing a prolate ellipsoidal primary mirror with a spherical secondary: independently discovered by Kirkham in the U.S.A. the type is now universally known as the Dall-Kirkham.

Alexander William Roberts, a great humanitarian and teacher in South Africa, was also a luminary in the astronomical world. This paper discusses his work on variable stars and touches briefly on his career in other areas. Born and educated in Scotland, Roberts migrated to South Africa in 1883, at age 25, to teach at the Native College at Lovedale. He studied mathematical astronomy as a recreational pursuit, but became an active observer in 1889. After two years of general observing, be began a systematic survey using binoculars and an old one-inch theodolite. He carefully plotted all visible stars in selected areas and ranked them in order of their apparent brightness, doing so repeatedly on six evenings for each of the selected areas. His composite sketch became a reference chart as he searched for changes in these fields. With this technique, Roberts discovered more than 20 variable stars.

The equipment used by professional astronomers in past centuries was no better than that used by modern amateurs. Systematic observation of the Sun began in the 17th century and continuity of observations is very important for understanding the solar cycle.

Results obtained from historical observations were presented, in particular covering the Maunder Minimum.

Continued systematic observation is important for the understanding of long-term solar-terrestrial relations.

Sailors are neither professional nor amateur astronomers, but people who have to observe the sky in the course of following their professional calling. As soon as sailors ventured far from the coast they required some guide and even in antiquity (as shown by mentions in Homer’s Odyssey and, considerably later, by Aratus) they used Ursa Minor and Ursa Major. With journeys farther afield, they gained some insight into latitude from the changes of the altitude of the circumpolar constellations above the horizon.

Although the very last Viking voyagers knew of the magnetic compass, earlier ones still relied on the Sun and the stars. Describing the methods used, Harald Akerlund says “One saga mentions a man, Oddi Heldagon, who was known as “Oddi the Star” and who served as long-distance pilot for an Icelandic magnate towards the end of the 900s. He left notes that included a complete table of the changes in declination of the Sun throughout the year, expressed as the height of the Sun on the meridian in semi-diameters. There is also a small table of azimuths giving the direction at different times of the year, of dawn twilight, defined as being a faint band of light on the horizon, visible before sunrise. We know nothing of the instrument used to measure the altitude of the Sun.”

In the Dauphiné, near Tullins, there is a fortified manor-house known as the Chateau de Saint-Jean-de-Chépy, built in the 13th century, that has in one of its towers an Italian Renaissance map of the heavens painted on the ceiling. The south tower could have been designed for astronomy, with the octagonal-roofed, second floor with its seven windows being used for observation. The first and ground floors have hemispherical vaults, and painted on the ceiling of the first floor there is a map of the heavens that is unique in France. It is painted on the ceiling, with the southern constellations extending down onto the cylindrical wall. It is similar to Italian Renaissance maps, like those in the Old Sacristy at San Lorenzo in Florence (painted by Brunelleschi in 1429), in the Villa Farnesine at Rome (Peruzzi, 1511), and in the Villa Farnese at Caprarola (artist unknown, 1575).

An owner of Saint-Jean-de-Chépy was Maurice Bressieu (1546–1617), a distinguished mathematician, holding the mathematical chair at the Collège de France between 1575 and 1586. He wrote Metrices Astronomicae, which was “highly regarded by mathematicians” and became Speaker for the Kings of France at the Vatican. Pope Sixtus-Quintus made him steward of the Vatican Library. It therefore seems very likely that the map could have been painted for him.

Historical events affected astronomy in France at this period. Large instruments were also rare so amateurs were on equal terms with professionals. Two significant amateurs are described:

Honoré Flaugerges (1755–1830), justice of the peace at Viviers (Ardèche), observed from 1782 until his death, in particular discovering two comets and recording sunspots.

Anne-Jean P.C. Duc-Lachappelle (1765–1814), studied astronomy in Paris, and set up an observatory in Montauban in 1789, mainly observing planets and Mercury in particular. He had one pupil, Bernier, and set up a local society for arts and sciences in 1796.

Both of these astronomers had numerous contacts with professional astronomers throughout Europe.

At that period there was keen popular interest in astronomy, and in many Paris squares, astronomers with terrestrial refractors gave talks on astronomy for a small sum. Léon Joubert created a observatory for scientific research and popularisation, allowing anyone to learn about the universe and use good instruments. He made 120 instruments: refractors, reflectors, projectors, and photographic instruments.

Hermann Goldschmidt (1802–1866), born at Frankfurt am Main 17 June 1802, had poor health, became a painter and sought his fortune in Paris. He became an astronomer by accident after following a course of lectures at the Sorbonne given by Le Verrier. From a modest studio on the 6th floor of an old house in the heart of Paris, he discovered 14 minor planets between 1852 and 1861, the first being called Lutetia by Arago.

When old people are questioned they often say that they vividly recall the appearance of Comet Halley in 1910. When, in 1985, we started to analyze that previous apparition, we fully expected to find remarkable accounts in the newspapers. But instead of dramatic stories of its appearance on the night of 1910 May 18–19, we find nothing was observed until May 28, because the sky over a large part of France (even Paris), was cloudy. Even then, it was described in terms such as “This wretched comet has a very over-inflated reputation, it appears more like a nebula than the object that we were led to expect.” So why then the popular excitment?