Giovanni Battista Riccioli

Giovanni Battista Riccioli (17 April 1598 – 25 June 1671) was an Italian astronomer and a Catholic priest in the Jesuit order. He is known, among other things, for his experiments with pendulums and with falling bodies, for his discussion of 126 arguments concerning the motion of the Earth, and for introducing the current scheme of lunar nomenclature. He is also widely known for discovering the first double star. He argued that the rotation of the Earth should reveal itself because on a rotating Earth, the ground moves at different speeds at different latitudes. The asteroid 122632 Riccioli is named after him.

Biography

Riccioli was born in Ferrara. He entered the Society of Jesus on 6 October 1614. After completing his novitiate, he began to study humanities in 1616, pursuing those studies first at Ferrara, and then at Piacenza. From 1620 to 1628 he studied philosophy and theology at the College of Parma. Parma Jesuits had developed a strong program of experimentation, such as with falling bodies. One of the most famous Italian Jesuits of the time, Giuseppe Biancani (1565–1624), was teaching at Parma when Riccioli arrived there. Biancani accepted new astronomical ideas, such as the existence of lunar mountains and the fluid nature of the heavens, and collaborated with the Jesuit astronomer Christoph Scheiner (1573–1650) on sunspot observations. Riccioli mentions him with gratitude and admiration. By 1628 Riccioli's studies were complete and he was ordained. He requested missionary work, but that request was turned down. Instead, he was assigned to teach at Parma. There he taught logic, physics, and metaphysics from 1629 to 1632, and engaged in some experiments with falling bodies and pendulums. In 1632 he became a member of a group charged with the formation of younger Jesuits, among whom Daniello Bartoli. He spent the 1633–1634 academic year in Mantua, where he collaborated with Niccolò Cabeo (1576–1650) in further pendulum studies. In 1635 he was back at Parma, where he taught theology and also carried out his first important observation of the Moon. In 1636 he was sent to Bologna to serve as Professor of theology. Riccioli described himself as a theologian, but one with a strong and ongoing interest in astronomy since his student days, when he studied under Biancani. He said that many Jesuits were theologians, but few were astronomers. He said that once the enthusiasm for astronomy arose within him he could never extinguish it, and so he became more committed to astronomy than theology. Eventually his superiors in the Jesuit order officially assigned him to the task of astronomical research. However, he also continued to write on theology (see below). Riccioli built an astronomical observatory in Bologna at the College of St. Lucia, equipped with many instruments for astronomical observations, including telescopes, quadrants, sextants, and other traditional instruments. Riccioli dealt not only with astronomy in his research, but also with physics, arithmetic, geometry, optics, gnomonics, geography, and chronology. He collaborated with others in his work, including other Jesuits, most notably Francesco Maria Grimaldi (1618–1663) at Bologna, and he kept up a voluminous correspondence with others who shared his interests, including Hevelius, Huygens, Cassini, and Kircher. He was awarded a prize by Louis XIV in recognition of his activities and their relevance to contemporary culture. Riccioli continued to publish on both astronomy and theology up to his death. He died in Bologna at 73 years of age.

Scientific work

Almagestum Novum

One of Riccioli's most significant works was his 1651 Almagestum Novum (New Almagest), an encyclopedic work consisting of over 1500 folio pages (38 cm x 25 cm) densely packed with text, tables, and illustrations. It became a standard technical reference book for astronomers all over Europe: John Flamsteed (1646–1719), the first English astronomer royal, a Copernican and a Protestant, used it for his Gresham lectures; Jérôme Lalande (1732–1807) of the Paris Observatory cited it extensively even though it was an old book at that point; the 1912 Catholic Encyclopedia calls it the most important literary work of the Jesuits during the seventeenth century. Within its two volumes were ten "books" covering every subject within astronomy and related to astronomy at the time:

the celestial sphere and subjects such as celestial motions, the equator, ecliptic, zodiac, etc. the Earth and its size, gravity and pendulum motion, etc. the Sun, its size and distance, its motion, observations involving it, etc. the Moon, its phases, its size and distance, etc. (detailed maps of the Moon as seen through a telescope were included) lunar and solar eclipses the fixed stars the planets and their motions, etc. (representations of each as seen with a telescope were included); comets and novae ("new stars") the structure of the universe—the heliocentric and geocentric theories, etc. calculations related to astronomy. Riccioli envisioned that the New Almagest would have three volumes, but only the first (with its 1500 pages split into two parts) was completed.

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