Giovanni Battista Riccioli — Ioannes Baptista Ricciolus on his Latin title pages — was an Italian Jesuit astronomer of Ferrara who taught at Parma and Bologna.
His Almagestum Novum (Bologna, 1651) was the most comprehensive astronomical encyclopedia of its century: it gave the Moon’s craters the names still used today, reported pendulum and falling-body experiments of remarkable precision, and weighed the arguments for and against Copernicus with a thoroughness no contemporary matched.
The ninth book, On the System of the World — the heart of that examination — is offered here in English for the first time.