From Alberto Martinez' book, this paragraph from a timeline of events regarding the Galileo and Bruno affairs.
1885 – Father William Roberts publishes his book The Pontifical Decrees Against the Doctrine of the Earth’s Movement. In this book, Fr. Roberts presents a strong case for the position that the Church’s condemnation of heliocentrism is infallible. He concludes: (1) Alexander VIII’s Speculatores was a papal act of supreme authority by which the pope, in the face of the whole Church, confirmed and approved the decrees with his Apostolic authority, and made himself responsible for their publication, that heliocentrism was false; (2) heliocentrism was false because the Church declared it a heresy, and whoever says an opinion is heresy ipso facto says that the contradictory of that opinion has been revealed by God with sufficient certainty to oblige a Catholic to accept it by an act of divine faith; and, (3) infallible teachings, even those ex-cathedra, do not generally generate any fresh obligation of faith, but protect and vindicate one that already exists.
According to John Daly's article on heliocentrism
, Fr. Roberts was a liberal Catholic who had major problems with the dogma of papal infallibility, and used the seeming about-face of the Church on geocentrism as a means of attacking infallibility, so it fits into his argument to argue that the original condemnation of heliocentrism was infallible even if it really wasn't.
In any case, that quote from Benedict XV pretty much does away with the argument that it's heretical to reject geocentrism. Obviously a pope can't say, in effect, "it appears geocentrism is not correct" in an encyclical, if geocentrism is a dogma of faith. It would be like a pope saying in an encyclical, "It appears there are four Persons in God." Such a thing is against the nature of the papacy.