Giovanni Riccioli

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Giovanni Battista Riccioli.jpg
Frontispiece of the Almagestum novum
The heliocentric theory of Copernicus is found to be too easy compared to Riccioli's model, in which the moon, the sun, Jupiter and Saturn orbit the earth and Mercury, Venus and Mars the sun.

Giovanni Battista Riccioli or Giambattista Riccioli , Latinized Johannes Baptista Ricciolus (born April 17, 1598 in Ferrara , † June 25, 1671 in Bologna ), was an Italian priest (since 1614 Jesuit ) and astronomer . Before he turned entirely to astronomy , he taught philosophy and theology for many years at the universities of Parma and Bologna .

As an astronomer, he was one of the pioneers of selenography , which later largely adopted his nomenclature of the lunar craters and seas . In his New Almagest , he contrasted heliocentrism with the Tychonic world system .

Theologian and astronomer

Giovanni Riccioli was an advocate of the geocentric worldview in the wake of Aristotle and Ptolemy , in which the spherical earth in the center of the universe is surrounded by all celestial bodies, such as the sun, moon and planets, on concentric orbits.

Like many other astronomers of his time, Riccioli tried to find evidence against the heliocentric worldview postulated by Nicolaus Copernicus , Johannes Kepler , and Galileo Galilei , but expressly did not consider it a heresy . In his multi-volume work Almagestum novum astronomiam ... from 1651 he even used Galileo's laws of fall and experiments as proof that the earth does not rotate and that the Tychonic worldview is physically and theologically the more plausible. It has not been proven whether he wanted to support the two decrees of Popes Paul V (1616) and Urban VIII (1633) against the Copernican view of the world .

The New Almagest is still known today because of the published moon map . The mapping of the moon was based on telescope observations that he and his assistant Francesco Maria Grimaldi made. Riccioli gave many formations names that are still valid today. He named striking moon craters after famous astronomers , scientists and philosophers , including Copernicus, Kepler and Galileo. He correctly recognized the light areas as highlands and called them "Terrae" (plural from Latin terra, land), while he called the dark areas (assuming water) as "Maria" (plural from Latin mare, sea) . In his most important publication, the Selenographia sive Lunae Descriptio of 1647, Johannes Hevelius had already introduced terms such as “ocean”, “golf”, “sea” and “mountain” to identify various lunar objects.

Works and discoveries

It is widely believed that Riccioli was the first to describe an optical double star , Mizar and Alkor in the constellation Great Bear (1650). However, there are indications that this constellation was discovered at the beginning of 1617 by Benedetto Castelli , an Italian scientist and friend of Galileo .

Riccioli discovered the shadows of Jupiter's moons on Jupiter . He also made observations of the rings of Saturn, but it was left to Christiaan Huygens to recognize and describe their true nature. In addition, Riccioli worked on a method to measure the sun's diameter .

He was also a staunch advocate of the Gregorian calendar .

Ricciolo considered the time measurement by comparison with the human pulse, which was still common in the middle of the 17th century, to be too imprecise after taking pulse measurements of his friars with the aid of a seconds pendulum and found pulse rates fluctuating from 50 to 85 beats per minute.


In honor of Giovanni Riccioli, two lunar structures were named after him:

  • the Riccioli crater with the coordinates 3 ° 18 ′ south / 74 ° 36 ′ west and a mean diameter of 139 km; it was named by the International Astronomical Union (IAU) in 1935;
  • the Riccioli Grooves ( Rimae Riccioli ) with the coordinates 2 ° 00 ′ south / 74 ° 00 ′ west and an average diameter of 400 km; it was named by the IAU in 1985 after the neighboring crater.

Publications (selection)


  • Geographicae crucis fabrica et usus ad repraesentandam ... omnem dierum noctiumque ortuum solis et occasum, Bologna 1643;
  • Almagestum novum astronomiam veterem novamque complectens observationibus aliorum et propriis novisque theorematibus, problematibus ac tabulis promotam, Vol. I-III, Bologna 1651;
  • Geographiae et hydrographiae reformatae libri duodecim, Bologna 1661 (2nd edition, Venice 1672);
  • Astronomia reformata, Vol. I-II, Bologna 1665;
  • Vindiciae calendarii Gregoriani adversus Franciscum Leveram, Bologna 1666;
  • Apologia RPIo. Bapt. Riccioli Societatis Iesu pro argumento physicomathematico contra systema Copernicanum, Venice 1669;
  • Chronologiae reformatae et ad certas conclusiones redactae tomus primus, Vol. I-III, Bologna 1669;
  • Tabula latitudinum et longitudinum, Vienna 1689.


  • Evangelium unicum Domini nostri Jesu Christi ex verbis ipsis quatuor Evangelistarum conflatum ..., Bologna 1667;
  • Immunitas ab errore tam speculativo quam practico definitionum S. Sedis Apostolicae in canonizatione Sanctorum ..., Bologna 1668;
  • De distinctionibus entium in Deo et in creaturis tractatus philosophicus ac theologicus, Bologna 1669.

Individual evidence

  1. ^ Thomas E. Woods: How The Catholic Church Built Western Civilization . Regnery, New York 2005, ISBN 0-89526-038-7 , pp. 71-102 online ( Memento of March 19, 2011 in the Internet Archive ).
  2. ^ A New View Of Mizar
  3. Giovanni Ricciol: Almagestum novum [...]. Volume 1, p. 88 f.
  4. Werner Friedrich Kümmel: The pulse and the problem of time measurement in the history of medicine. In: Medical History Journal. Volume 9, 1974, pp. 1–22, here: p. 6.

Web links