Aristotle writes Metaphysics and Prior Analytics. Founded the school called the Lyceum

Ptolemy writes the Almagest, a comprehensive treatise on the movements of the stars and planets. Developes the Ptolemaic System, Earth is at the center of the universe. Catalogues 48 constellations.

Copernicus publishes De Revolutionibus Orbium Coelestium ("On the Revolutions of the Heavenly Spheres"). Introduces the heliocentric solar system model.

Discovers the Galilean moons of Jupiter. Publishes "Dialogue Concerning the Two Chief World Systems", it supports the Copernican heliocentric model of the solar system.

Writes The First Law: Planets move in ellipses with the Sun at one focus. Publishes "Astronomia Nova" with the First Law, and the Second Law: The radius vector describes equal areas in equal times. Discovers The Third Law: The squares of the periodic times are to each other as the cubes of the mean distances. Publishes "Harmonices Mundi".

Discovers Saturn's moons: Iapetus, Rhea, Tethys and Dinoe. Cassini and Richer use the parallax method to determine the distance of Mars from Earth. Discovers a division in Saturn's rings called the Cassini Division.

Proposed that a thin, flat ring circled Saturn, discovered the moon Titan. Makes the first known drawing of the Orion Nebula. proposes a wave theory for light.

Publishes "Philosophiæ Naturalis Principia Mathematica", contains his 3 laws of motion and the universal law of gravitation.

Formulates his special theory of relativity, the laws of physics are the same everywhere, the speed of light is constant. Formulates his famous equation: E=mc^{2,} where E is energy, m is mass and c is the speed of light. Publishes the theory of general relativity. Receives the Noble Prize.

Proposes a galaxy classification sysetm. Four classes: spirals, barred spirals, ellipticals and irregulars. Discovers that the universe is expanding at an astronomical rate, known as Hubble's Law.

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