Most experts rejected this revolutionary theory, which contradicted both Church teachings and the teachings of Ptolemy. In Europe, all scientific knowledge and many religious teachings were based on the arguments developed by classical thinkers. If Ptolemy's reasoning about the planets was wrong, then the whole system of human knowledge might be called into question.

In the late 1500s, the Danish astronomer Tycho Brahe (TEE koh BRAH uh) provided evidence to support Copernicus's theory. Brahe set up an astronomical observatory. Every night for years, he carefully observed the sky, accumulating data about the movement of the heavenly bodies.

After Brahe's death, his assistant, the brilliant German astronomer and mathematician Johannes Kepler used Brahe's data to calculate the orbits of the planets revolving around the sun. His calculations supported Copernicus's heliocentric view. At the same time, however, they showed that each planet does not move in a perfect circle, as both Ptolemy and Copernicus believed, but in an oval-shaped orbit called an ellipse.

The Church Rejects Galileo's Discoveries

Scientists from many different lands built on the work of Copernicus and Kepler. In Italy, Galileo Galilei used new technology to assemble an astronomical telescope. With this instrument he became the first person to see mountains on the moon. He observed that the four moons of Jupiter move slowly around that planet—exactly, he realized, the way Copernicus said that Earth moves around the sun.

Galileo's discoveries caused an uproar. Other scholars attacked him because his observations contradicted ancient views about the world. The Church condemned him because his ideas challenged the Christian teaching that the heavens were fixed, unmoving, and perfect.

In 1633, Galileo was tried before the Inquisition, and spent the rest of his life under house arrest. Threatened with death unless he withdrew his “heresies,” Galileo agreed to state publicly in court that Earth stood motionless at the center of the universe. However, legend has it that as he left the court he muttered, “And yet it moves.”

A New Scientific Method

Despite the opposition of the Church, by the early 1600s a new approach to science had emerged. Unlike most earlier approaches, it started not with Aristotle or Ptolemy or even the Bible but with observation and experimentation. Most important, complex mathematical calculations were used to convert the observations and experiments into scientific laws. In time, this approach became known as the scientific method.

Revolutionary Scientific Thinkers

The new scientific method was really a revolution in thought. Two giants of this revolution were the Englishman Francis Bacon and the Frenchman René Descartes (day KAHRT). Each devoted himself to understanding how truth is determined.

Both Bacon and Descartes, writing in the early 1600s, rejected Aristotle's scientific assumptions. They also challenged the medieval scholars who sought to make the physical world fit in with the teachings of the Church. Both argued that truth is not known at the beginning of inquiry but at the end, after a long process of investigation.

Painting of a bearded man showing diagram of the moon to men in red robes and caps, one of whom is looking through a telescope. A book on a table is a work of Galileo Galilei.

Galileo explains to skeptical church officials that the moon's phases reflect its relation to the earth and the sun. Galileo studied the moon through a special telescope he built for the purpose.


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Table of Contents

World History Topic 1 Origins of Civilization (Prehistory–300 B.C.) Topic 2 The Ancient Middle East and Egypt (3200 B.C.–500 B.C.) Topic 3 Ancient India and China (2600 B.C.–A.D. 550) Topic 4 The Americas (Prehistory–A.D. 1570) Topic 5 Ancient Greece (1750 B.C.–133 B.C.) Topic 6 Ancient Rome and the Origins of Christianity (509 B.C.-A.D. 476) Topic 7 Medieval Christian Europe (330–1450) Topic 8 The Muslim World and Africa (730 B.C.-A.D. 1500) Topic 9 Civilizations of Asia (500–1650) Topic 10 The Renaissance and Reformation (1300–1650) Topic 11 New Global Connections (1415–1796) Topic 12 Absolutism and Revolution Topic 13 The Industrial Revolution Topic 14 Nationalism and the Spread of Democracy (1790–1914) Topic 15 The Age of Imperialism (1800–1914) Topic 16 World War I and the Russian Revolution (1914–1924) Topic 17 The World Between the Wars (1910–1939) Topic 18 World War II (1930–1945) Topic 19 The Cold War Era (1945–1991) Topic 20 New Nations Emerge (1945–Present) Topic 21 The World Today (1980-Present) United States Constitution Primary Sources 21st Century Skills Atlas Glossary Index Acknowledgments