Simon Marius | |
|---|---|
 Engraving of Marius in his bookMundus Iovialis (World of Jupiter), 1614 | |
| Born | Simon Mayr (1573-01-10)10 January 1573 Gunzenhausen, Principality of Ansbach |
| Died | 5 January 1625(1625-01-05) (aged 51) Ansbach, Principality of Ansbach |
| Known for | Naming thefour largest moons of Jupiter and studyingAndromeda Galaxy |
| Scientific career | |
| Fields | Astronomy |
Simon Marius (Latinized form ofSimon Mayr; 10 January 1573 – 5 January 1625)[1] was a Germanastronomer. He was born inGunzenhausen, nearNuremberg, but spent most of his life in the city ofAnsbach. He is best known for being among the first observers of thefour largest moons ofJupiter, and his publication of his discovery led to charges ofplagiarism.
Marius was the son of Reichart Mayr, a mayor of Gunzenhausen.[2] On the recommendation ofGeorge Frederick, Margrave of Brandenburg-Ansbach, he was admitted to the Margrave's Academy inHeilsbronn in 1586, where he studied until 1601.[3] During this time, he published observations about a comet as well as astronomical tables, which gave him a reputation as a good astronomer and mathematician, and the Margrave appointed him as his official mathematician.[2] Marius wanted to attend theUniversity of Königsberg, but was unable to get a scholarship.[3] However, the Margrave wrote a letter of recommendation on 22 May 1601, so that Marius could study inPrague underTycho Brahe, which he did for several months,[2] although he may actually have worked directly withDavid Fabricius instead of Brahe himself.[3]
By September 1601, Marius had already left Prague and he arrived inPadua in December 1601 to study medicine at theUniversity of Padua.[1] During this time, he tutored other students in astronomy, including oneBaldassarre Capra, with whom he wrote a book on a new star (actuallyKepler's Supernova) which they had observed in 1604.[2] Capra had a dispute withGalileo Galilei (both of them learnedfencing from Capra's father[4]) on the invention of theproportional compass and Marius took his student's side in the argument.[3] Marius left the school in July 1605, returning to Ansbach to become the mathematician and physician to the new Margraves,Christian andJoachim Ernst.[2]
In 1606, Marius married Felicitas Lauer (born 1590), the daughter of his publisher, in Ansbach,[5] and in 1609 he published the first German translations ofEuclid'sElements. That year, he also built his own telescope and made observations of theGalilean moons, around the same time that Galileo did himself; the priority of discovery became a major dispute between the two.[2]
Capra published another book in 1607 that he had plagiarised from Galileo. Marius was implicated in the act due to his prior association with Capra, even though this was after Marius had left Padua. Galileo certainly was under that impression, as he referred to his "old adversary" (without explicitly naming Marius) as a "poisonous reptile", and an "enemy of all mankind".[2]
In 1614, Marius published his workMundus Iovialis (English:World of Jupiter) describing the planetJupiter and its moons (he previously had published the discovery in 1611 in a local almanac[6]). Here he claimed to have discovered the planet's four major moons about a month before Galileo, who was incensed.[7] InThe Assayer in 1623, he accused Marius of plagiarism.[2]
Because of Galileo's stature in the scientific community, for nearly 300 years, Marius's reputation was tainted by Galileo's accusations. However, a scientific committee in the Netherlands in 1903 examined the evidence extensively and ruled in favor of Marius's independent discoveries, with results published byJohannes Bosscha in 1907.[8] Marius had discovered the moons independently but had not noted it until 29 December 1609. Marius used theJulian calendar, and that date is equivalent to 8 January 1610, in theGregorian one used by Galileo, one day after Galileo's letter in which he first described the moons.[6]
Regardless of priority, the mythological names by which these satellites are known today (Io,Europa,Ganymede andCallisto) are those given them by Marius:[9]
Io, Europa, Ganimedes puer, atque Calisto
lascivo nimium perplacuere Iovi.
Simon Marius also observed theAndromeda "nebula", which had also been known to PersianMuslim astronomers of theMiddle Ages.[10]
Discussion of Marius's work is scarce, but what exists tends to note his skill as an observer, including:
Marius drew conclusions about the structure of theuniverse from his observations of the Jovian moons and the stellar disks. The stellar disks he observed were spurious (likely theAiry disk caused bydiffraction, as stars are too distant for their physical disks to be detected telescopically), but Marius interpreted them to be physical disks, like the planetary disks visible through a telescope. He concluded that since he could see stellar disks, the stars could not be as distant as was required in theCopernican world system, and he said that the appearance of the stars as seen through a telescope actually argued against Copernicus.[16] These findings are contrasting to those of Galileo, who utilized similar telescopic data alternatively to support the Copernican world system.[17] This adherence by Galileo to the Copernican heliocentric theory arises due to its apparent mathematical grandeur and his prior commitment to the theory.[18] Marius, however, showed no evident commitment to any theory but rather hypothesized based on telescopic observation. He also concluded from his observations of the Galilean moons that they must orbit Jupiter while Jupiter orbits the Sun.[19] Therefore, Marius concluded that the geocentricTychonic system, in which the planets circle the Sun while the Sun circles the Earth, must be the correct world system, or model of the universe.[16]
