Nj

Ptolemy: He proposed the Ptolemaic system, where planets move in small circles called epicycles, which are in turn orbiting Earth.

Proposed a model of the universe with nesting spheres, Earth at the center

• Aristotle: He proposed a geocentric model of the universe, with Earth at the center and concentric spheres carrying the planets and stars.

Found evidence for the heliocentric model including phases of Venus and Jupiter's moons

• Galileo Galilei: Using a telescope, Galileo observed the phases of Venus and the moons of Jupiter, providing key evidence supporting the heliocentric model proposed by Copernicus.

Proposed elliptical orbits rather than circular orbits for the planets

• Johannes Kepler: He formulated Kepler’s laws of planetary motion, with the groundbreaking discovery that planets move in elliptical orbits, not circular ones.

Built the best observatory and proposed the geo-heliocentric model of the solar system

• Tycho Brahe: Brahe constructed advanced observatories and proposed a geo-heliocentric model, where the planets orbit the Sun, but the Sun orbits the Earth.