2 0 0 9 P a r i s / M e u d o n

2 0 0 9 P a r i s / M e u d o n

IWCMO Conference

Stéphane LECOMTE: About Some French Martian Observers

Talk given at the IWCMO conference, Paris, 18^th September 2009

N this talk, I will mention some Frenchmen, some famous, others nearly forgotten, who have observed the planet Mars from the end of nineteenth century to the first half of the twentieth century. My goal is not to do a history of early French Martian’s research; I wish only to remember some past astronomers who’ve been involved in improving our knowledge of the red planet.

(2) I cannot begin without saying few words about the Paris Observatory, who welcomed us yesterday. It was, in late seventeenth century, a great place of planetary observing with Gian Domenico Cassini and Gian Filippo Maraldi.

(3) But the discovery of the rotation of Mars, by Cassini in 1666, took place in Italy before his arrival in Paris.

Despite many observations and discoveries (Saturn’s satellites, follow up of Jovian’s clouds, for example) the physical studies of the planets have experienced a long eclipse in France probably due to several causes as the great difficulties to use the long aerial refractors but also the fact that the Paris Observatory's astronomers were engaged, at this time, in geodesic survey for mapping the kingdom. From then on, French astronomers developed a long standing interest in positional astronomy and celestial mechanics.

(4) Thus in his book "La Planète Mars et ses conditions d'habitabilité", Flammarion, have quoted only the observations of Messier, Flaugergues and Arago for the eighteenth and first half of nineteenth centuries.

Probably the most famous French amateur astronomer at the end of nineteenth century, Camille Flammarion, was the main promoter of renewal in planetary observations, in France.

(5) In 1858, at sixteen, he became a student astronomer at the Paris Observatory. But far from his dreams of observing the celestial wonders, he devoted his days to reducing meridian observations. Four years later, following the publication of his first book “The plurality of inhabited worlds”, he left the observatory. According to the legend, he was dismissed by its director, Urbain Leverrier, the famous Neptune discoverer's. He then became a science journalist and began a prolific career as a writer.

Convinced of the existence of life on other planets, his whole life he would be fascinated by Mars.

(6) In his first book, already, he outlined the similarity between Earth and Mars. The presence of an atmosphere, clouds, polar snows appearing and disappearing periodically, the dark spots evoking seas, a seasonal cycle similar to Earth have suggested him the possibility that Mars was an inhabited world. Ten years later, having acquired a small refractor (with an aperture of 108mm) and after observing the red planet, he sent his first communication about it at the Academy of Sciences, concluding to probability of life on a surface covered by vegetation and seas. Bringing together the observations, from numerous observers, available at his time he drew a new map of Mars in 1877 that he presented at the Academy of Sciences.

(7) In 1879 he published his book ”Astronomie Populaire”, a best seller who gave him great fame. Another fallout, more unexpected, was the gift, in 1882, by an admirer, of a magnificent property at Juvisy, near Paris. He could finally realize his dream of building an observatory with a powerful instrument, in this case a 24cm refractor with which he observed all Martian oppositions. But being a busy man, he was unable to devote much of his time observing himself. In order to operate properly his observatory, he invited many talented observers to use it. Among them I can quote Eugène Antoniadi, Gaston Millochau, Théophile Moreux that we shall see later.

His greatest contribution to the study of the red planet is not so much in his observations, than in his work of collecting and diffusing knowledge about this planet, notably in the ”Bulletin de la Société Astronomique de France”.

(8) He gathered all Martian observations until 1909 in his two-volumes book "La Planète Mars et ses conditions d'habitabilité,” work of reference for all interested by the red planet. The first volume, published in 1892 has a great incidence on history's of Mars observations, being at the origin of Lowell's passion for this planet and the building of his observatory at Flagstaff.

Unfortunately, even if he said working on a third tome, for updating this work, this one was never published.

Great popularizer, multiplying conferences and books, at the origin of the Astronomical Society of France, he is at the root of many astronomical vocations and a renewed interest for the observation of planets in France.

(9) But before Flammarion, we can probably say that the first great French Mars's observer was Etienne Leopold Trouvelot. Born in 1827, he needed to leave France for some political reasons, and he settled in 1855, in Massachusetts. Here it was at the origin of an environmental disaster after a risky experiment in rearing silkworms and their accidental release on the American continent. In 1872 after distinguishing himself by his artistic talents having realized magnificent drawings of auroras and of a shooting stars rain, he joined the Harvard College Observatory, having use of the 37,5cm refractor. One year later he built his own observatory equipped with a refractor of 16cm. From then to his death, he observes and draws the Moon, the Sun, the planets, deep sky objects and many astronomical phenomena. He left us a fabulous set of watercolors about celestial bodies.(10)

In 1882, following his desire to return to France, and on the recommendation of Camille Flammarion he was hired by Jules Janssen at Meudon's Observatory mainly to observe and draw every day the sun with a refractor of 20 cm. He used it until his death in 1895.

(11) In a paper published in 1881, he summarized his observing program: ”In the year 1876, a series of observations on the planets Mercury, Venus, Mars, Jupiter and Saturn was undertaken with the intention of following each one of these bodies for as many years as necessary to study them on every point of their orbit, in order to arrive at a better knowledge of their physical constitution and meteorology. The plan, then formed, was to make at least one observation and a drawing of each planet on every favorable day, whenever the object would be so situated that it could be advantageously observed.”

When he died he left thousands of drawings of Venus, Jupiter and Mars. If he published a lengthy study on the planets Mercury and Venus, in the”Bulletin of the Astronomical Society of France”, his observations of Mars and Jupiter unfortunately does not appear to have been exploited. His observing records are kept by the Paris Observatory’s library. His Mars observing notebook contains 465 drawings done from 1877 to 1895.

As each of us knows it, at perihelic opposition of 1877, Italian astronomer Giovanni Schiaparelli has observed strange linear formations on the surface of Mars, the famous canals. Despite a campaign of unprecedented observations, he was then, alone to observe them.

In the following oppositions few observers have saw these lines, only Schiaparelli described them regularly. From then, their existence has puzzled astronomers.

(12) In 1881, Henri Perrotin was appointed Director of the newly created Nice Observatory. Two years later he could use a 38 cm refractor with which he got great results on the planets Saturn and Uranus. Convinced of the excellence of his instrument, he turned it to Mars, but the opposition was already passed since two months.

In 1886, he devised an observations program aimed at the recognition of single or dual channels discovered by Schiaparelli. His first attempts were a failure and when he wanted to give up, he saw a first canal between Syrtis Major and Sinus Sabaeus. From then on, with his colleagues Louis Thollon and Charles Trépied, he regularly observed many canals.

(13) At the next opposition, in 1888, he can use the large refractor of 76 cm, who has just been inaugurated. He saw again the canals and described some changes about its surface like the disappearance of Libya.

Now, he seemed more concerned by changes at the Martian surface because in his reports he mentions only marginally canals, probably because for him we could not doubt their existence.

In 1892, he was puzzled by bright projections on the planet's limb.

As he was the French leading observer of Mars, Jules Janssen offered him to used, in December 1895 and January 1896, the newly commissioned great refractor with an aperture of 83cm. He was the first to observe with this instrument, the second largest in the world at this time. But these observations have added nothing new.

He seems not to take part further in the debate about the nature of the canals. He concludes: “The changes that sometimes occurred in the canals have not, for us, the nature of regularity accepted by other observers”. To my knowledge he never suggested any ideas about their nature.

(14) The mystery of Martian canals will be solved (at least for some!), a century ago, by the observations of Antoniadi, that we celebrate this day. However before Antoniadi, another man, with the same instrument, had reached the same conclusions, Gaston Millochau.

Since there is no published biography or obituary for this astronomer, this work is a first attempt to discover this man.

(15)       Born in 1866, he probably started as an amateur astronomer. According to Joseph Vinot, editor of the ”JOURNAL DU CIEL”, the first French popular astronomy newspaper, it is on his recommendation that he was hired as Henry Deslandres assistant at the Paris Observatory in the spectroscopy service. At this time, we found him visiting regularly the Juvisy’s observatory where he probably met Antoniadi.

   For many years he will be the main collaborator of Henry Deslandres accompanying it in several missions for observing total solar eclipses (Senegal in 1893, Japan in 1896, Spain in 1900. He has observed a fourth eclipse, again in Spain in 1905 with Janssen).

   Late 1897, he was appointed assistant astronomer and follows Deslandres to the Meudon Observatory, where he regularly used the large refractor, notably for visual and spectroscopic observations of planets.

From 1903, he has conflicted with Deslandres and he requested from Observatory's director, Jules Janssen, to leave the spectroscopy team. From 1904 his researches focused on the study of the Sun's temperature and the solar constant. For this research he observed many times at the Mont Blanc observatory, erected by Janssen, staying here, once, thirteen consecutive days at the summit. Certainly not a very comfortable place, even in August!

In 1906 he was awarded the Janssen Prize (a gilt medal) from Academy of Sciences for his work on solar physics.

The next year, he left Meudon Observatory and he came back to Paris Observatory.

In 1910, a month mission to the Pic du Midi observatory for observing Halley's comet was plagued by inclement weather. The following year he was the author of a popularizing book “De la Terre aux Astres” (From Earth to Stars).

Due to the war, having suffered from a great shock, (I have not found more details) he disappeared from astronomical circles in 1915. We don't know his fate neither when he died. It was only after 1919.

(16) He observed Mars with the Meudon great refractor in 1899 and the two following apparitions. In 1901, summarizing his observations of Mars, he concluded “I saw the canals as like a chain of small dark masses”.

(17) Two years later, he added: "The canals, who in the average refractors, are saw as slight lines, quite thin, but a little fuzzy, lose this appearance in the great refractor; they seem then to be due to dark discontinuous spots, with jagged edges, forming some kinds of rosaries that are joined in line by the eye when the vision is not concentrated on one point."

But his conclusions seem not to have attracted great attention. Probably because he was not known as Antoniadi was in 1909 and, we can see, his drawings are not so impressive than those realized some years later by the Greek astronomer.

(18) Despite the observations of Millochau and Antoniadi, some French astronomers continue to observe canals. For example, Robert Jonckheere, a young amateur who became later a celebrated observer of double stars, just opened his observatory near Lille, a gift from his father for his majority. He owned a refractor of 35 cm, the largest in France in a private observatory. Presumably seeking to affirm the quality of his instrument, as early as August 1909 he turned it to Mars, focusing primarily on the southern polar cap.(19) From 1 September he begins to observe the canals discovered by Schiaparelli and Lowell, adding some new. It does not seem to have observed Mars at other oppositions probably due to the subjectivity of all visual observations leading to controversy around his own Martian observations as attested by a set of papers in “Astronomische Nachrichten”, opposing him to Antoniadi.

(20) A close friend of Antoniadi, Father Théophile Moreux was, like Flammarion, a great French popularizer, but probably less known abroad. He published more than one hundred books, half devoted to astronomy. Born in 1867, he owes his passion to his father, who in his childhood, showed him a comet and to his reading of Flammarion’s books. In 1891 he sent his first observations to the Société Astronomique de France (Saturn and solar spots with a 57mm refractor). Two years later he was invited to observe at Juvisy's observatory where he met Antoniadi. The latter sold him his refractor. Later he set up his first observatory at the Bourges seminary’s. But he lost him with the law separating state and church, in the 1906.

(21) He needed it two more years to build a new observatory at the top of a Moorish style building, surprising in the French countryside! He was equipped with a 16cm equatorially mounted refractor.

If his main interest was observing the Sun and the Earth-Sun relationships (22), Mars was, for him, another favorite target. He has realized hundred drawings of Mars, confessing to have observed it sometimes six or eight consecutive hours. Opponent to the geometrical representation of Mars and to the artificial nature of canals, he opposed in a little booklet, published in 1924, ”La Vie sur Mars” (Life on Mars), to the existence of intelligent beings on Mars. (23) We can see he was a skilled observer by comparing his drawing of Mars with one's of Antoniadi realized the same night, with a refractor five times smaller!

(24) I think one of the most interesting French amateur astronomers was Rene Jarry-Desloges. As Percival Lowell, he has devoted his fortune to the study of planets, especially Mars. During nearly thirty years he was in search of the best astronomical site. He has set up in several sites, in France and Algeria (French at this time), many astronomical stations with powerful instruments. He has surrounded himself with skilled observers notably his main collaborator, Georges Fournier.

(25) This table summarizes the characteristics of the different observatories. Only the Setif observatory was installed permanently from 1924, the other stations being only temporary. He used refractors from different manufacturers, with apertures from 26 to 50cm performing comparisons between them. He was always wishing to understand and improve all the observing parameters.

(26) Between 1907 and 1941, only two Mars oppositions, in 1933 and 1939 will not be followed. He published all his observations in a set of 10 books, that he distributed at his own expense worldwide, "Observations des surfaces planètaires". They are illustrated with many beautiful drawings of all planets.

(27) He studied and recognized the changes in aspects of the Martian surface and particularly the importance of atmospheric phenomena. He focused particularly on polar cap regression. Many canals were observed in his observatories and if he had no doubt about their reality he gave them a natural origin. Wisely, in his last volume, he leaves the reader to draw conclusions, himself, from the study of all his work.

or a long time, the main instrument of French amateur astronomers was a 108mm [one hundred and eight] refractor, too small for really contribute to improving our knowledge of Mars. But with the growing development of astronomy, notably due to the work of Flammarion, we started to find some amateurs with bigger instruments.

(28) One of them was, René Schlumberger who has built a beautiful observatory, but he is now totally forgotten. Sorry, I have not found any picture of him. Alsacian manufacturer, in 1911 he joined the Astronomical Society of France, but it was not until 1924 that he began to send regularly his observations made using a Secretan’s refractor of 11 cm.

(29) In 1928, in Mulhouse, he installed a telescope of 22.5 cm under a dome of 5m with which he obtained images of great quality. With this remarkable achievement, which earned him much praise, he devoted himself to observing the Moon and planets, sending regularly the fruit of his work to the Astronomical Society of France.

(30) In 1933, probably after retirement, he moved his observatory to Nice, on French Riviera, where he observed during at least another ten years under a better weather. He was involved with the first works of the newly created Mars Committee at Astronomical Society of France. Here are some drawings he executed with paintbrush and ink diluted, according to a learnt technique from Antoniadi.

(31) Finally, I would like to mention an astronomer who was not directly a Mars observer’s, but whose work is linked to this planet, Julien Peridier. He took an interest in astronomy when he was a young student and joined the Astronomical Society of France at sixteen, before joining other foreign societies as the British Astronomical Association. With limited means, having only binoculars, he was primarily focused on shooting stars and variable stars.

(32) After a break during nearly 25 years, probably due to his professional duties, he established an observatory in 1933 in a small village in southwestern France, Le Houga. His two main instruments were a reflector (with a diameter of 31cm) and a 20cm refractor, each instrument was housed under a 4m dome.

(33) Wishing to make the most of his observatory, he opened it to any astronomer (amateur or professional) wishing to conduct astronomical research. Thus Le Houga was selected as one of the stations for a Harvard Observatory expedition to observe the occultation of Regulus by Venus in 1959. The following years this collaboration has continued through a program of multicolor photoelectric photometry of the Moon and planets with the reflector. But more interesting for us, was his collaboration from 1939 with a young astronomer Gérard Oriano de Vaucouleurs who became famous later for his research on galaxies.

(34) Having started by observing the heavens with a small refractor, he joined the Société Astronomique de France and used his observatory. In 1939 he actively participated in the creation of the Mars committee at Astronomical Society of France, becoming his first secretary. At Le Houga, he conducted observations of Mars during many oppositions. Thus he studied the reality of the dark fringe bordering the polar cap whose existence was largely controversial. His main contribution was to introduce a more quantitative analysis to the Martian studies notably by developing the system of visual intensity estimates. The collaboration between the two men has lasted at least ten years without limiting to the planet Mars.

(35) Of course, all the astronomers I have presented in this talk are not the only ones to have studied Mars in France during this period. It is not an exhaustive list. We can mention Ferdinand Quénisset, Gabrielle Flammarion (the second wife of Flammarion), Lucien Rudaux without forgotten the numerous observers having used, during many decades, the Société Astronomique de France observatory’s as Jacques Camus or André Danjon who, later, became director of Paris Observatory.

For many years, generations of astronomers have devoted a lot of time, energy and money to improve our knowledge or just glimpse the mysteries of the red planet. Not all have do major discoveries but all were fascinated by the planet Mars. Behind all of our current knowledge there are men, I wished, through some of them, pay tribute to them.

Stéphane LECOMTE

Société Astonomique de France

Auteur de nombreux articles historiques sur l’observation des planètes

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