Simon Marius (Latinized from German Simon Mayr; January 20, 1573 –
January 5, 1625) was a German astronomer. He was born in Gunzenhausen,
near Nuremberg, but he spent most of his life in the city of Ansbach.
In 1614 Marius published his work Mundus Iovialis describing the
Jupiter and its moons. Here he claimed to have discovered the
planet's four major moons some days before Galileo Galilei. This led
to a dispute with Galileo, who in
Il Saggiatore in 1623 accused Marius
of plagiarism. However, a jury in The Netherlands in 1903 examined the
evidence extensively and ruled in favor of Marius's independent
discoveries, with results published by Bosscha in 1907. Apparently
Marius discovered the moons independently, but started keeping notes
one day later than Galileo, when Marius's date in the Julian calendar
is increased by 10 days to convert to the Gregorian calendar used by
Regardless of priority, the mythological names by which these
satellites are known today (Io, Europa, Ganymede and Callisto) are
those given them by Marius:
Io, Europa, Ganimedes puer, atque Calisto
lascivo nimium perplacuere Iovi.
Io, Europa, the boy Ganymede, and Callisto greatly pleased lustful
Simon Marius also observed the Andromeda "nebula", which had also been
known to Arab astronomers of the Middle Ages.
Discussion of Marius's work is scarce, but what exists tends to note
his skill as an observer, including:
That in 1612 he measured the diameter of the Andromeda nebula and
discerned it as having a dull, pale light which increased in
brightness toward its center, like "a candle shining through
That he detected the spurious disks of stars created by his
That, from his observations of the Jovian moons he derived better
periods of revolution and other orbital elements for them than did
That he observed the location of Tycho Brahe's supernova of 1572 and
found a star there which he estimated to be "somewhat dimmer than
Jupiter's third moon."
Marius drew conclusions about the structure of the universe from his
observations of the Jovian moons and the stellar disks. The stellar
disks he observed were spurious (likely the
Airy disk caused by
diffraction, 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 the Copernican world system, and he
said that the appearance of the stars as seen through a telescope
actually argued against Copernicus. He also concluded from his
observations of the Jovian moons that they must orbit
Jupiter orbits the Sun. Therefore, Marius concluded that the
geocentric Tychonic 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.
Mundus Iovialis anno MDCIX Detectus Ope Perspicilli Belgici (Die Welt
des Jupiter, 1609 mit dem flämischen Teleskop entdeckt; Lateinisches
Faksimile und deutsche Übersetzung; Hrsg. und bearb. von Joachim
Schlör. Naturwiss. begleitet und mit einem Nachw. vers. von Alois
Zinner, E., "Zur Ehrenrettung des Simon Marius", in:
Vierteljahresschrift der Astronomischen Gesellschaft, 77. Jahrgang, 1.
Heft, Leipzig 1942
Bosscha, J., "Simon Marius. Réhabilitation d´un astronome
calomnié", in: Archives Nederlandaises des Sciences Exactes et
Naturelles, Ser. II, T. XII, pp. 258–307, 490–528, La Haye,
^ Pasachoff, Jay M. (May 2015). "Simon Marius's Mundus Iovialis: 400th
Anniversary in Galileo's Shadow". Journal for the History of
Astronomy. 46 (2): 218–234. Bibcode:2015JHA....46..218P.
^ Marius/Schlör, Mundus Iovialis, p. 78 f. (with misprint In for Io)
^ Bond, George P,"An Account of the Nebula in Andromeda",Memoirs of
the American Academy of Arts and Sciences, New Series, volume 3, 1848
^ Watson, Fred, Stargazer: The Life and Times of the Telescope, Da
Capo Press, 2005, pg. 86.
^ Dreyer, JLE,"The Tercentenary of the Telescope",Nature,vol. 82
(December 16, 1909), pp. 190–191
^ Pannekoek, Anton, A History of Astronomy, Interscience Publishers,
1989, pg. 231.
^ Waldrop, M. Mitchell,"
Supernova 1987 A: Facts and
Fancies",Science,New Series, Vol. 239, No. 4839 (Jan. 29, 1988), pp.
^ Marius/Schlör, Mundus Iovialis, pp. 46–49.
^ Marius, Simon (tr. by A.O. Prickard), "The Mundus Jovialis of Simon
Marius", The Observatory (astronomy), vol. 39, 1916, pg. 404, 408, 409
^ Marius/Schlör, Mundus Iovialis, pp. 46–49.
Portal — Mathematician – Medical Practitioner –
The Galileo Project — biography of Simon Marius.
Simon-Marius-Gymnasium — Simon-Marius-Gymnasium Gunzenhausen, named
after the astronomer.
Online Galleries, History of Science Collections, University of
Oklahoma Libraries High resolution images of works by and/or portraits
Simon Marius in .jpg and .tiff format.
O'Connor, John J.; Robertson, Edmund F., "Simon Marius", MacTutor
History of Mathematics archive, University of St Andrews .
ISNI: 0000 0000 8388 1042