Скачать или смотреть How Copernicus, Tycho, and Kepler Challenged the Earth-centered Model | Astronomy Masters Program

The ideas introduced by Copernicus fundamentally changed the way we perceive our place in the universe. The story of this dramatic change, known as the Copernican revolution, is in many ways the story of the origin of modern science. It is also the story of several key personalities, beginning with Copernicus himself.

Copernicus was born in Torun, Poland, on February 19, 1473. His family was wealthy and he received an education in mathematics, medicine, and law. He began studying astronomy in his late teens.

By that time, tables of planetary motion based on the Ptolemaic model had become noticeably inaccurate. But few people were willing to undertake the difficult calculations required to revise the tables. The best tables available had been compiled some two centuries earlier under the guidance of Spanish monarch Alphonso X (1221–1284). Commenting on the tedious nature of the work, the monarch is said to have complained, “If I had been present at the creation, I would have recommended a simpler design for the universe.”

In his quest for a better way to predict planetary positions, Copernicus decided to try Aristarchus’s Sun-centered idea, first proposed more than 1700 years earlier. He had read of Aristarchus’s work, and recognized the much simpler explanation for apparent retrograde motion offered by a Sun-centered system. But he went far beyond Aristarchus in working out mathematical details of the model. Through this process, Copernicus discovered simple geometric relationships that allowed him to calculate each planet’s orbital period around the Sun and its relative distance from the Sun in terms of the Earth-Sun distance. The model’s success in providing a geometric layout for the solar system convinced him that the Sun-centered idea must be correct.

Copernicus was nevertheless hesitant to publish his work, fearing that his suggestion that Earth moved would be considered absurd. However, he discussed his system with other scholars, including high-ranking officials of the Catholic Church, who urged him to publish a book. Copernicus saw the first printed copy of his book, De Revolutionibus Orbium Coelestium (“On the Revolutions of the Heavenly Spheres”), on the day he died—May 24, 1543. Publication of the book spread the Sun-centered idea widely, and many scholars were drawn to its aesthetic advantages. However, the Copernican model gained relatively few converts over the next 50 years, for a good reason: It didn’t work all that well. The primary problem was that while Copernicus had been willing to overturn Earth’s central place in the cosmos, he held fast to the ancient belief that heavenly motion must occur in perfect circles. This incorrect assumption forced him to add numerous complexities to his system (including circles on circles much like those used by Ptolemy) to get it to make decent predictions. In the end, his complete model was no more accurate and no less complex than the Ptolemaic model, and few people were willing to throw out thousands of years of tradition for a new model that worked just as poorly as the old one.

Part of the difficulty faced by astronomers who sought to improve either the Ptolemaic or the Copernican model was a lack of quality data. The telescope had not yet been invented, and existing naked-eye observations were not very accurate. Better data were needed, and they were provided by the Danish nobleman Tycho Brahe (1546–1601), usually known simply as Tycho (pronounced “tie-koe”).

Tycho was an eccentric genius who lost part of his nose in a sword fight with another student over who was the better mathematician; he designed a replacement nose piece made of silver and gold. In 1563, Tycho decided to observe a widely anticipated alignment of Jupiter and Saturn. To his surprise, the alignment occurred nearly 2 days later than the date Copernicus had predicted. Resolving to improve the state of astronomical prediction, he set about compiling careful observations of stellar and planetary positions in the sky.

Tycho’s fame grew after he observed what he called a nova, meaning “new star,” in 1572. Its lack of observable parallax led Tycho to conclude that the nova was much farther away than the Moon, a fact that contradicted the ancient Greek belief in unchanging heavens. (Today, we know that Tycho saw a supernova—the explosion of a distant star.) In 1577, Tycho made similar observations of a comet and showed that it too lay in the realm of the heavens. Others, including Aristotle, had argued that comets were phenomena of Earth’s atmosphere. King Frederick II of Denmark decided to sponsor Tycho’s ongoing work, giving him money to build an unparalleled observatory for naked-eye observations.. After Frederick II died in 1588, Tycho moved to Prague, where his work was supported by German emperor Rudolf II.

Material for this video was taken from the book "Cosmic Perspective 8th ed. by Bennett, Donahue, Schneider, and Voit