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Geminiano Montanari.

Geminiano Montanari (June 1, 1633 – October 13, 1687) was an Italian astronomer, lens-maker, and proponent of the experimental approach to science.

He is best known for his observation, made around 1667, that the second brightest star (called Algol as derived from its name in Arabic) in the constellation of Perseus varied in brightness. It is likely that others had observed this effect before, but Montanari was the first named astronomer to record it. The star's names in Arabic, Hebrew and other languages, all of which have a meaning of "ghoul" or "demon", imply that its unusual behaviour had long been recognised.

Montanari was born in Modena, studied law in Florence, and graduated from the University of Salzburg. In 1662 or 1663 he moved to Bologna, where he drew an accurate map of the Moon using an ocular micrometer of his own making. He also made observations on capillarity and other problems in statics, and suggested that the viscosity of a liquid depended on the shape of its molecules. In 1669 he succeeded Giovanni Cassini as astronomy teacher at the observatory of Panzano, near Modena, where one of his duties was to compile an astrological almanac. He did so in 1665, but perpetrated a deliberate hoax by writing the almanac entirely at random, to show that predictions made by chance were as likely to be fulfilled as those made by astrology. In the period shortly after Galileo Galilei, experimentalists like Montanari were engaged in a battle against the more mystical views of scientists such as Donato Rossetti.

On 21 March 1676 Montanari reported a sighting of a comet to Edmund Halley.

Montanari's observations of the great comet of 1680 are mentioned twice in the third volume of Newton's Principia.[1]

In 1679 Montanari moved to a teaching post in Padua, but almost all records of this period of his life have been lost. A letter survives from 1682 recording a sighting of Halley's Comet. He also wrote on economics, observing that demand for a particular commodity was fixed, and making comments on coinage and the value of money (1683).

A crater on the Moon, at 45.8S, 20.6W, is named after him.


Prostasi fisicomatematica, 1669
  • De motionibus naturalibus a gravitate pendentibus (1667)
  • Pensieri fisico-matematici (1667)
  • La Livella Diottrica (The Spirit Level) (1674)
  • Trattato mercantile delle monete (1680)
  • L'Astrologia Convinta di Falso col Mezzo di Nuove Esperienze e Ragioni Fisico-Astronomiche o sia la Caccia del Frugnuolo (1685), in which Montanari describes his and his colleagues' random predictions intended to disprove astrology


  1. ^ Isaac Newton, The Principia: Mathematical Principles of Natural Philosophy, edited by Bernard I. Cohen and Anne Whitman, Berkeley, University of California Press, 1999, pp. 913-915, 927.

Further readings[edit]

  • Gómez López, Susana, Le passioni degli atomi. Montanari e Rossetti: Una polemica tra galileiani, Florence, Leo S. Olschki, 1997.
  • Rotta, Sergio, 'Scienza e "pubblica felicità" in G. Montanari', in Miscellanea Seicento, Florence, Le Monnier, 1971, vol. 2, pp. 65-208.
  • Vanzo, Alberto, 'Experiment and Speculation in Seventeenth-Century Italy: The Case of Geminiano Montanari', Studies in History and Philosophy of Science, 56 (2016), pp. 52-61.

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Geminiano_Montanari — Please support Wikipedia.
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136 news items


Mon, 25 Jan 2016 04:22:30 -0800

Faccio presente inoltre che siamo dovuti intervenire nuovamente su via Geminiano Montanari, poco prima del parco Da Vinci, dove è stato sventato un furto di cavi di rame, che abbiamo scoperto essere stati tranciati di netto pronti quindi per essere ...

Corretta Informazione (Satira)

Corretta Informazione (Satira)
Sat, 16 Jan 2016 10:33:45 -0800

Mediaworld Da oggi 16 gennaio 2016 ha inizio il torneo che decreterà il miglio giocatore di FIFA 16. Il gioco in questione ha fatto della sfida il suo marchio di fabbrica, costringendo giocatori di tutto il mondo a sfidarsi prima in multiplayer ...

Huffington Post

Huffington Post
Tue, 29 Dec 2015 08:37:34 -0800

It was previously thought that Italian astronomer Geminiano Montanari discovered Algol in the late 1660s, but the researchers concluded that the "demon star" was discovered much earlier -- and that the ancient Egyptian papyrus is the oldest preserved ...


Fri, 20 Nov 2015 13:23:24 -0800

This week, between 11 p.m. and midnight local time, the constellation immortalizing one of the greatest heroes of Greek mythology — Perseus — will pass directly overhead. Its prominent variable star, Algol — known as "the Demon" — will be vividly ...

Community Idea Stations

Community Idea Stations
Wed, 06 Jan 2016 06:48:34 -0800

Until recently, Geminiano Montanari was credited with the discovery of Algol in 1667, but this find shows that perhaps this variable star was of more importance to humanity much earlier. Regardless, this find further shows us how the ancient world ...

Astronomy Now Online

Astronomy Now Online
Fri, 18 Dec 2015 14:45:07 -0800

An extract of the Cairo Calendar papyrus (1244–1163 B.C.). The University of Helsinki scholars present evidence that the 2.85-day period in the Cairo Calendar is equal to that of the eclipsing binary Algol during this historical era. They show that ...

New Historian

New Historian
Fri, 01 Jan 2016 17:46:02 -0800

It was formerly believed that Geminiano Montanari, an Italian astronomer, had discovered Algol sometime in the late 1660s. Now researchers have concluded the Demon Star had been found much earlier. The research was recently published in the journal ...


Thu, 19 Feb 2015 15:08:27 -0800

The first person who definitely noticed Algol's winking behavior was the Italian professor of mathematics Geminiano Montanari of Bologna around the year 1667. At that time the only other variable star known (save for a few novae) was Mira, whose light ...

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