Nicolaus Copernicus, who lived from 1473 until 1543, is known
for his idea that the sun is motionless at the center of the
universe and that the earth and other planets all revolve around
it. This Polish astronomer revolutionized beliefs involving the
universe, making his thoughts controversial in his time, but
common knowledge in our own (Westman). Before the time of
Copernicus, people had extremely different views of the
universe. A Greek astronomer named Ptolemy had his own theory of
the earth and its relationship with the sun and other planets.
Around 140 AD, he came up with a system that showed the earth at
the center of the universe with the sun and planets revolving
around it in a spherical shape (Reichenbach 15-17). Ptolemy also
believed that the earth remained still and that the outermost
sphere contained the stars, which were fixed in space (Westman).
Copernicus's theory showed the earth and other planets revolving
around the sun in a circular motion. At the same time, the moon
is rotating around th