Astronomy contributions

• Created the concept of a Geocentric Universe
• Objects in the heavens are perfect spheres
• Object on Earth naturally want to be at rest

First introduce the idea of a heliocentric model

Geographer who predicted the Earth's circumference to be around 5,000 Stadia which is around 3-15 percent error to modern measurements

• Invented trigonometry
• Made the first star atlas
• Device a scale based on relative brightness for stars

• Created a workable set of equations to predict planetary motion to strengthen the argument of a geocentric model
• Created the idea that planets have mini orbits to explain retrograde motion

• Published "De Devolutionibus Orbium Celestium" on his deathbed
• Explained retrograde motion
• Invented the AU unit

• Documented Mars orbit for 20 years.

• Created the Galilean telescope
• Discovered the moons of Jupiter

• Introduced the idea of orbiting eclipses
• Created 3 laws of planetary motion

• 3 law of motion
• Invented Calculus
• Discovered Gravity