ASTRONOMERS

Aristotle

• Aristotle was a Greek philosopher and scientist born in the Macedonian city of Stagira, Chalkidice.
• "Aristotle was the first genuine scientist in history ... [and] every scientist is in his debt."

ARISTARCHUS

• He was a Greek astronomer and mathematician.
• Aristarchus contributed by trying to measure the relative distances to the moon and sun.

PTOLEMY

• He lived in the city of Alexandria in the Roman province of Egypt, wrote in Greek, and held Roman citizenship.
• Ptolemy developed a detailed geocentric model that was used for the next 14 centuries.

COPERNICUS

• Nicolaus Copernicus was a Renaissance mathematician and astronomer who formulated a model of the universe that placed the Sun rather than the Earth at its center.
• Copernicus developed the first detailed heliocentric model of the solar system.

KEPLER

• Kepler was a mathematics teacher at a seminary school in Graz, Austria, where he became an associate of Prince Hans Ulrich von Eggenberg.
• Kepler made many discoveries like the planets move in elliptical orbits with the Sun at one focus; and the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc (the “area law”)

GALILEO GALILEI

• Galileo Galilei, often known mononymously as Galileo, was an Italian physicist, mathematician, engineer, and astronomer, who played a major role in the scientific revolution during the Renaissance.
• Galileo made significant improvements to the newly invented telescope.

GEOCENTRIC MODEL

• In astronomy, the Geocentric Model (also known as geocentrism, or the Ptolemaic system) is a description of the cosmos where Earth is at the orbital center of all celestial bodies.

HELIOCENTRIC MODEL

• The heliocentric model is a theory that places the Sun as the center of the universe, and the planets orbiting around it. The heliocentric model replaced geocentrism, which is the belief that the Earth is the center of the universe.

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