Galileo discovered evidence to support Copernicus’ heliocentric theory when he observed four moons in orbit around Jupiter. Beginning on January 7, 1610, he mapped nightly the position of the 4 “Medicean stars” (later renamed the Galilean moons). Over time Galileo deduced that the “stars” were in fact moons in orbit around Jupiter. [Adapted from Galileo Galilei, 1610, Sidereus Nuncius (“The Starry Messenger.”)]
In the early 1600s,
Galileo Galilei (1564-1642) refined the recently developed telescope and pointed it to the heavens. There he saw lots of fascinating things, like tiny specks moving around Jupiter. Being a gifted artist, Galileo made great recordings of many celestial sites, including the Jovian moons and the phases of Venus, and came to realize the moons were circling Jupiter and Venus was circling the sun.
If moons moved around Jupiter and Venus around the sun, those bodies could not be circling Earth. Galileo became a proponent of heliocentrism, a sun-centered solar system. That's what got Galileo crossed up with church doctrine, which up to then taught geocentrism, the idea that the Earth was at the center of everything. Which brings us to Ted Cruz's latest mangling of science and history:
Speaking to the Texas Tribune on Tuesday, Cruz said that contemporary “global warming alarmists are the equivalent of the flat-Earthers.”
“You know it used to be it is accepted scientific wisdom the Earth is flat, and this heretic named Galileo was branded a denier,” he said. In Cruz’s opinion, when it comes to climate change, his denier position places him alongside 17th Century scientist Galileo Galilei, who was also considered to be denying the mainstream knowledge of his day. According to Cruz’s logic, he is taking the minority view that human-caused climate change is not happening, just as Galileo took the minority view that the scientific method should be trusted over the Catholic Church.
To Cruz's point, Galileo did not discover the Earth was round. Thanks to lunar eclipses and
other clever observations, many ancients came to know that over two-thousand years ago. The Greek mathematician
Eratosthenes accurately calculated the Earth's size and shape in about
240 BC. Columbus argued it decades before Galileo was born. Moreover, the scientific method hadn't been formalized yet, there were no scientists in the modern sense of the word, and thus there was no such thing as scientific consensus. But there were loads of people every bit as ignorant and self-righteous as Ted Cruz.