In my last post I commented on the priority disputes that Galileo carried out with other users of the telescope in the early years of telescopic astronomy. Some of his most vitriolic comments were launched from the pages of his polemical pamphlet The Assayer against the Franconian astronomer Simon Marius, who was born on 10th January 1573, for daring to claim in his Mundus Jovialis published in 1614 that he and not Galileo had first discovered the moons of Jupiter. This was provocation beyond all measure as the discovery of the Jupiter moons was by far and away the greatest of Galileo’s scientific triumphs.
Born Simon Mayr (Mayer in its almost endless orthographic variations, ask PZ, is the most common family name in the German Language) in the then village of Gunzenhausen (it’s now a town) about 60 kilometres south of Nürnberg, Marius the son of a barrel maker received a school stipend from the local Margrave because of his beautiful singing voice. His mathematical talents were recognised early and he published his first astronomical work, observations of a comet in 1596. The local Lord, Joachim-Ernst Margrave of Ansbach appointed him court astronomer/astrologer and paid for him to spend six months studying under Tycho Brahe in Prague in 1601, where he also made the acquaintance of David Fabricius. Following this his patron paid for him to go to the University of Padua, where Galileo was Professor of Mathematics, to study medicine. In the Renaissance there was a very close connection between medicine and astronomy through the astrological medicine that was then in fashion and which I will blog about some day. It is not recorded if Marius and Galileo met but they certainly knew of each other’s existence because of an ugly incident concerning Galileo’s military or proportional compass; this is a multi-purpose calculating instrument. Galileo did not invent this instrument but he did design and market a superior model for which he gave personal instruction to the purchasers including supplying them with an unpublished set of instruction, all for the necessary fees of course. One of Marius’ private pupils Baldessar Capra stole Galileo’s pamphlet and published it as his own work. Galileo brought charges of plagiarism against Capra and he was found guilty and punished and at that time, 1607, Galileo exonerated Marius, who had returned to Ansbach in 1605, of all blame in the affair.
In 1608 the Margraves chief political advisor Johann Philipp Fuchs von Bimbach, a distinguished German soldier and diplomat, visited the autumn Fair in Frankfurt were a Dutch peddler offered to sell him a telescope, it should be noted that this was two weeks before Lipperhey first presented his telescope in Den Hague. The instrument had a cracked lens and the price was exorbitant so Fuchs von Bimbach did not purchase but on his return to Ansbach he told Marius of the incident and sketched diagrams of the lenses. The two were unable to get suitable lenses ground in Nürnberg, then the leading centre for the manufacture of spectacle lenses in Europe, so instead they imported a telescope from Holland. Later the purchased superior lenses from Venice and built their own telescope. It was with this instrument that Marius discovered the moons of Jupiter.
Unlike Galileo who, realising the capital that he could make out of his discovery, rushed into print with his legendary Sidereus Nuncius, Marius first published his discovery four years later in 1614. Galileo’s friends and supporters immediately informed the Maestro of the pretentious German who was out to steal his glory and although enraged he did not react at once. First in The Assayer published in 1623, his attack on the Jesuit astronomer Orazio Grassi in their dispute on the true nature of comets did Galileo unleash his venom on the German upstart. Not only did Galileo thunder against him for daring to steal his discovery of the Jupiter moons but he now made him responsible for Capra’s earlier theft of the military compass, completely ignoring his own exoneration of Marius from 1607. Poor Marius didn’t have a chance. Galileo was at the height of his powers a feted courtier in the glory that was Renaissance Rome and the most famous scientist in Europe whereas Marius was a nobody from the German provinces, a court astrologer with a proven bad reputation. Public opinion condemned him immediately as a plagiarist and a thief and he went to his grave in 1624 as an intellectual criminal. Interestingly Galileo played the religious card condemning Marius as a protestant and even the Jesuit astronomer Christoph Scheiner who had had his own bitter dispute with Galileo over the discovery of the sunspots sided with Galileo against the Calvinist (sic) intellectual thief, who was in fact a Lutheran.
Marius’ reputation remained ruined until the end of the 19th century when historians for the first time objectively examined the facts. It turned out that Marius’ data was different to Galileo’s and in fact his determination of the orbits of the four moons was superior to that of his rival. The astronomical data showed that Marius was not a plagiarist but an independent observer who deserves an honourable place in the history of astronomy. At first glance it would appear that Marius made his first recorded observation of the Jupiter moons before Galileo but appearances deceive. Marius, a protestant, was still using the Julian calendar whereas Galileo, a Catholic, was using the Gregorian one; making the necessary conversion Marius discovered the moons exactly one day later than Galileo.