Today marks the 378th anniversary of the day the Inquisition forced Galileo to say he was wrong— that the Earth did not revolve around the sun. Galileo had made the proclamation in his book Dialogue Concerning the Two Chief World Systems, and whether he really believed what he was saying that summer day is debatable. Legend has it that after he recanted his views, Galileo muttered, “And yet it moves,” under his breath, but David DeVorkin, senior curator at the National Air and Space Museum, says there’s no historical basis for that claim.
“I would never say he didn’t say it,” DeVorkin said, “but the best historians say there’s no proof.”
DeVorkin, an expert on the history of astronomy and astrophysics who has been known to stargaze with Galileo himself, told me the story of what really happened.
The atmosphere in Italy at the time that Galileo was writing his book was tense. The Roman Inquisition was underway, and even more significantly, the bubonic plague was sweeping the country, making travel and communication extremely difficult and creating a sense of fear in the population.
Before Dialogue was published, Galileo was favored by the Church, even earning a pension from the pope, but officials were angered by the book’s content. The plot featured three characters: a simpleton, a student and a sage, who debated the structure of the solar system. The simpleton supports an Earth-centered view of the solar system, and is subsequently proven wrong and ridiculed by the other characters. This was considered to by heresy because it ran contrary to the modern views of the Church, which supported that vision. It also undermined contemporary ideas about the structure of the universe and the placement of heaven and hell.
“It made the universe physical,” DeVorkin said, “and then people had to ask, where in the world is heaven?”
In addition, several officials were offended as they believed the character of the simpleton was, in part, a representation of themselves.
“The real issue was the nature of the Dialogue that seemed to lampoon some sensitive personalities who were either on the Inquisition or were advisors or patrons or something,” DeVorkin said. “They did not want to be made out as fools.”
Galileo was found guilty of heresy and sentenced to house arrest, where he remained until his death in 1642. Today, he is featured in two of the National Air and Space Museum’s exhibits, Explore the Universe and Exploring the Planets. which tell the still-evolving story of the way we see our solar system and the universe as a whole. Galileo’s assertion that the planets revolved around the sun, in addition to his myriad other contributions to science, was an integral part of that evolution.
“He really was one of the first modern scientists,” DeVorkin said. “He added rigorous observation to the scientific toolkit. He also added the earliest concepts of relativity and the concept of infinity. Without Galileo, I’d like to think these things would have happened, maybe in a different way, but who knows?”