Saturday, July 4, 2020

The ‘canali’ of Mars

Giovanni Virginio Schiaparelli, the Italian astronomer, died one hundred and ten years ago today. He is particularly remembered for his observations and descriptions of the planet Mars, as well as for his studies of ancient astronomy. He kept diaries, mostly scientific, for some of his working life, often illustrating them, and, although not published, they have been used as a primary source for some astronomy history papers.

Schiaparelli was born in Savigliano, northern Italy, in 1835. He graduated in engineering from the University of Turin in 1854, and, with the help of influential friends, went on to study and research astronomy at Berlin Observatory under Johann Franz Encke, and at Pulkovo Observatory near St Petersburg. Returning to Italy in 1860, he was appointed second astronomer at the Brera Astronomical Observatory, in Milan, becoming its director in 1862, and remaining so for the best part of 40 years. He married Maria Comotti in 1865, and together they parented five children. His first discovery at Brera
, in 1861, was the asteroid Hesperia. This was followed in 1886 by the discovery of a connection between the orbits of comets and meteors (for which he was awarded he Gold Medal of the Royal Astronomical Society in 1872).

In 1875, with a new refractor telescope, Schiaparelli began measurements of double stars, and then, from 1877, during the Mars opposition that year (when Mars is closest to Earth), he launched a long and ultimately important series of observations of the planet over a 20 year period (benefiting from a new telescope and rebuilt dome in 1885). His work was published in several papers by Reale Accademia dei Lincei (of which he was a member) together amounting to the then most detailed monograph on the physical appearance of Mars. In 1893, he published his main work on the subject, La vita sul pianeta Marte (Life on Mars). Interestingly, when he first described (and illustrated - see photo of stamp) a dense network of linear structures that he had found on the surface of the planet, he called them ‘canali’ or channels, but the word was mis-translated in English as ‘canals’ - i.e. artificial constructions. The mistake led to a wave of popular theories about potential life on Mars which carried on through the first half of the 20th century.

Schiaparelli was also a senator of the Kingdom of Italy. After his retirement, he studied the astronomy of the ancient Hebrews and Babylonians and wrote L’astronomia nell’antico testamento, 1903 (Astronomy in the Old Testament). He died on 4 July 1910. Further information is available from Wikipedia, Osservatorio Astronimoco di Brera, Encyclopaedia Britannica, a biography in the Journal of the British Astronomical Association (available at Astrophysics Data System), or David Darling’s website.

There is not much information in English about Schiaparelli’s diaries online, other than a 2011 paper on The Diary of Schiaparelli in Berlin (26 October 1857-10 May 1859): a guide for future scientific activity by P. Tucci. This can be found online at the Journal of the Italian Astronomical Society. According to Tucci, ‘the diary is very important for the reconstruction of Schiaparelli’s training as an astronomer.’ He goes on: ‘The Diary is written in a nice calligraphy, especially the section on the lectures of the winter semester 1857-’58. The Diary contains a wealth of relevant information on the training of the young scientist and the emergence of the wide spectrum of interests. The first part is basically focused on a detailed account of the first semester of the academic year 1857-’58. Almost every lesson is told with great details and the writing is probably a transcript of notes taken during the lesson. Over the months, however, more space is gradually won over by the tale of personal stories and unfolding of episodes of common everyday life, all at the expense of the University lectures.’ Tucci’s paper focuses on astronomy rather than the ‘personal stories’.

Here is an extract from Tucci’s analysis of Schiaparelli’s diary: ‘With the beginning of 1858. Giovanni Virginio began to attend the Berlin Observatory, headed by Encke. It’s firstly quoted in Friday. January 8. when he claims: “I went to the Observatory to find Encke, and gave him the reduction of the observations made on last 8 September of which he was very happy”. After being in the library, Giovanni Virginio came back again to the Observatory, where he was able to observe “. . . quite well at the meridian passage of the Sun”; he also took the opportunity “. . . to see in a very clear way how the Sun is able to change the shape of the instruments.” Also Sunday, 17 Giovanni Virginio “. . . went to the Observatory, first to observe the Sun at noon, then in the evening, where in spite of fresh air I gathered a harvest of at least 24 passages. It’s strange that the Observatory was empty, and no one observed except me. Is this a work of slaves?” ’

Another 2011 paper on Schiaparelli and his legacy, by A. Manara and G. Trinchieri, includes several images (illustrations and texts) from the diaries - as shown here. The manuscript diaries are held in the archives at the Brera Observatory.

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