Nicolaus Copernicus:
His Place in the History of Astronomy

• c.262 - 190 BC - Appolonius of Perga
• c.190 - 120 BC - Hipparchus, ancient Greek astronomers who developed a mathematical model describing the motion of the sun and the moon around a slightly off-center Earth, and the motion of planets around the Earth based on the epicycle deferent system. In addition, Hipparchus is given credit for compiling a catalog describing the position and magnitude of 850 stars. He also recognized the phenomenon known as the procession of the equinoxes.
• 384 - 332 BC - Aristotle, Greek Philosopher and scientist, proposed a mechanical, geocentric model of the cosmic universe with the Earth at rest. This model was used for the next 20 centuries.
• 100 - 170 AD - Ptolemy, Greek astronomer, mathematician and geographer. Author of the Almagest which gives a detailed mathematical model of the geocentric system.
• 1473 - 1543 - Copernicus (Mikołaj Kopernik), Polish astronomer and mathematician, author of the now universally accepted heliocentric model of the solar system which revolutionized man's view of the universe.
• 1514 - 1574 - Rheticus (Goerge Joachim), mathematician, Copernicus' disciple. Deserves credit for obtaining Copernicus' permission to print De Revolutionibus and taking the manuscript to Nuremberg where it was printed.
• 1564 - 1643 - Galileo Galilei, Italian mathematician, astronomer and physicist. Was the first to use the telescope for astronomical observations. A strong proponent of Coperrucanism.
• 1546 - 1601 - Tycho Brache, Danish astronomer, opponent of the Copernican theory, proposed his own geocentric/ heliocentric system. Developed astronomical instruments which increased the measurement accuracy (Copernicus' accuracy, better than 6', Brache's accuracy, usually better than 4' but could be even as good as 1'). His observations of the planets were used to verify the Copernican model.
• 1571 - 1630 - Johannes Kepler, German astronomer and mathematician. Strong proponent of the Copernican theory. Best known for three laws, named after him, which govern the motion of planets along elliptical orbits.
• 1642 - 1727 - Isaac Newton, English physicist and mathematician. Among his numerous discoveries is the theory of gravity which describes the motion of heavenly bodies.