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Sphaera Mundi
Guiseppe Bianchani (1566 – 1624)
Bononiae: Typis S. Bonomij, sumptibus Hieronymis Tamburini, 1620
First edition
GA7 B57

One of the most immediate consequences of the telescopic observations of Galileo in 1609-10 was the discussion it generated among the mathematicians and astronomers of the Society of Jesus. They reproduced Galileo’s observations and debated the cosmological order of the universe taking into consideration the new data. The debate culminated in the adoption of Tycho Brahe’s system and was made official with the publication of Giuseppe Bianchani’s Sphaera Mundi. The Jesuit Bianchani fully accepted Brahe’s amendation of the Copernican cosmography which acknowledged the heliocentricity of the planetary system, while preserving the geocentricity of the universe. Bianchani wrote his treatise in 1615, but it was not published until 1620, after the Decree of the Congregation of the Index in 1616. Written at the request of his students, Bianchani respectfully cites Brahe, Copernicus, Galileo, and Kepler repeatedly. He discusses the satellites of Jupiter and Saturn, sunspots, and the new stars of 1572, 1600, and 1604, astronomical phenomena not observed before the development of the telescope. Bianchani also presents his own theory of the earth’s tendency toward roundness, wherein natural forces operate to flatten mountains and fill valleys so that the surface would be completely covered by the ocean, as it was in the early formation of the earth. Bianchani writes that God created the earth on the third day as a smooth sphere. God then created the depths of the sea and formed the mountains. One of the many woodcuts in the text is an illustration of the moon, with very inaccurately drawn craters. Another is the first illustration of a thermometer.