Copernicus was born in Torun, Poland, on February 19, 1473. Little is known about his early life except that his father died when he was 10. An uncle adopted him, his two sisters, and his brother. The uncle saw to it that the two boys received a good education. Copernicus went to the University of Cracow. There he studied such subjects as Latin, mathematics, and astronomy. It was probably at that time that he changed his Polish name, Niklas Koppernigk, to the Latin form. of Nicolaus Copernicus. In 1496 Copernicus went to Italy, where he spent the next 10 years studying at various universities. In Copernicus time people still believed that all things—the sun, the stars, and the planets moved around the earth. It was an old belief that few men had ever questioned. Aristotle had based his theory of astronomy on this belief. Because the Church had long been the center of learning, the theory was also linked to religious beliefs. In 1506 Copernicus returned to his homeland. A few years later he began to work for the Church. All those years Copernicus carried on his work in astronomy. He had just the most basic equipment and, like other scientists of his day, made observations with only his eyes. Still, using mathematics and logic, Copernicus worked out a different theory, which held that the planets went around the sun. Copernicus did not announce his ideas. He did not want to make trouble. But he could not hide the scientific truth. So he talked about his theory with his friends, who strongly advised him to have his work published. His great book, On the Revolutions of the Heavenly Bodies, appeared at the very end of his life. Copernicus saw the first copy on the day he died, May 24, 1543.

From the passage we can see that astronomy is ______.