In the period between the Dialogo sopra i due massimi sistemi del mondo (1632) by Galileo Galilei and of the Philosophiae Naturalis Principia Matemathica (1687) by Isaac Newton, astronomy was in a stalemate. Earth, stars, and planets were usually observed by means of the telescope at that time: the resolving power of this instrument already allowed for the development of selenography and the improvement of the celestial data. Astronomers wanted to figure out the true world-system, and there were two contenders: the heliocentric system and the geo-heliocentric system. Each of these solutions had different versions, although they remain linked to their inventors: on one hand, the heliocentric system invented by Nicolaus Copernicus had its epigone in the work of Johannes Kepler; on the other hand, the geo- heliocentric system, elaborated by Tycho Brahe, was originally reinterpreted by Giovanni Battista Riccioli (1598-1671).
The work of the latter, an Italian Jesuit born in Ferrara and culturally active in Bologna, is considerable: Riccioli furnished a priceless quantity of information, data, observations, useful to understand what astronomy really was in that period. His work shows the astronomers’ awareness of the new data and discoveries but also their suspicions toward the new philosophy of nature. Many scholars have praised Riccioli’s expertise and complained about his lack of originality. It is necessary to understand, however, whether he had put a methodology into practice, in what sense he used the hypotheses and why he reached solutions that he considered only “probable”. We have reasons to say that he had his own method of investigation, even though he did not speak explicitly about it.
The proposal of Riccioli (essentially reported in Almagestum novum, 1651) was a planetary system where the Earth is at the center of the universe and the Moon, the Sun, Jupiter and Saturn turn around the Earth. Mercury and Venus turn around the Sun. So, the Earth and the Sun are the centers of the celestial cinematic, in a way that the orbits of the other planets must be described in relation to both of them. The trajectories are quasi-ouali, elliptical, achieved by means of the variation of the epicycle and of the oscillation of the eccentric. Riccioli named his system “epic-epicycles” system (epicepicyclos).
The Jesuit did not achieve a dynamic for his system. He was not able to understand the Galilean principle of inertia or the principle of composition of motion in some contexts. He tried to integrate his cinematic with ontology and metaphysics, and, in this way, he explained the celestial matter. The Jesuit knew very well scholastic theology and ancient philosophy and he proposed a revision of some metaphysical and epistemological principles. In his system, the celestial matter was fluid and made like the Earth. No angelic intelligence moved the planets: indeed, theology cannot and must not explain what belongs to the domain of astronomy, and vice-versa, theology cannot pretend to be justified by astronomic arguments. Consequently, the cause of celestial motion was still unknown. Nevertheless, theology is able to propose that the world was created by a Creator, who made the world generally unalterable (ab extrinseco incorruptibiles), but locally alterable (ab intrinseco corruptibiles).
Why did Riccioli not become a Copernican? Was he scared of the Catholic Church? Or rather, was he really persuaded that the Earth is stable at the center of the universe? In the seminar, I sustain that no definitive answer can be formulated based on the sources examined up to the present moment. Nevertheless, Riccioli is the evidence of what astronomy was after Galileo and before Newton.

References
Borgato, M.T. (ed.) (2002). Giambattista Riccioli e il merito scientifico dei Gesuiti nell’età barocca. Firenze: Leo S. Olskhki.
Dinis, A. (2017). A Jesuit against Galileo? The strange case of Giovanni Battista Riccioli Cosmology. Braga: Axioma - Publicações da Faculdade de Filosofia.
Evans, J. (1998). The History and Practice of ancient Astronomy. New York-Oxford: Oxford University Press.
Marcacci, F. (2018). Cieli in contraddizione. Giovanni Battista Riccioli e il terzo sistema del mondo. Perugia-Modena: Aguaplano-Accademia delle Scienze Lettere e Arti.
Riccioli, G.B. (1651). Almagestum novum, 2 voll. Bononiæ: Ex Typographia Hæredis Victorij Benatij.