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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.

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


  • The Passions of the Atoms. Montanari and Rossetti: A Polemic Between Followers of Galileo by Susana Gomez Lopez, Florence, Leo S. Olschki, 1997.

External links[edit]

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


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

The so-called "demon star" of Algol is the most prominent eclipsing variable star in the night sky, and if you know when and where to look, you can see the star appear to wink as it is eclipsed by another, dimmer star. This variable star eclipse occurs ...

World Socialist Web Site

World Socialist Web Site
Sun, 20 Apr 2014 21:18:45 -0700

In 1667, the Italian astronomer Geminiano Montanari noted that the star Algol changed its brightness. It was not until 1783 that British astronomer John Goodricke noted that these changes in brightness were always the same and occurred with clockwork ...
Fri, 07 Sep 2012 14:14:17 -0700

It appears that the first astronomer who definitely noticed Algol's periodic dimmings was Geminiano Montanari of Bologna, around the year 1667. At that time the only other known variable star was Mira, in the constellation of Cetus, the Whale. But ...


Wed, 01 Jul 2015 06:18:45 -0700

Dove: Market da Vincivia Geminiano Montanari snc,Roma; Quando: Dal 09/07/2015 Al 09/07/2015: 20:24; Costo: Vai al sito; Ti Piace? Il ranking di questo elemento non è visibile per la tua utenza. Il ranking di questo elemento non è votabile dalla tua utenza.


Wed, 08 Jul 2015 02:00:00 -0700

Algol ( Beta Persei) è una binaria ad eclisse, variabile di tipo Algol, scoperta dall'astronomo italiano Geminiano Montanari nel 1669. Ogni 2 giorni, 20 ore e 49 minuti, questa stella variabile ci appare al minimo di luminosità ( magn. +3.4), ciò ...


Fri, 22 May 2015 08:00:00 -0700

Ultima domenica per i dinosauri nella capitale! Paleontologi di ogni età troveranno dalle 10.00 alle 21.00 negli spazi del parco commerciale Da Vinci (via Geminiano Montanari) le riproduzioni su scala delle loro creature preferite. Dal T-Rex al ...
Universe Today
Mon, 22 Oct 2012 08:00:01 -0700

Italian astronomer Geminiano Montanari was the first to record that Algol occasionally “faded,” and its methodical timing was cataloged by John Goodricke in 1782, who surmised that it was being partially eclipsed by a dark companion orbiting it. Thus ...
Discovery News
Wed, 02 May 2012 10:49:16 -0700

This unusual feature was first noticed back in 1667 by an astronomer named Geminiano Montanari, and later confirmed — with a proposed possible mechanism — in 1783 by John Goodricke, who precisely measured the period of variability: it dims every ...

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