ARISTOTLE

• 384-322 BCE
• He thought Earth was the center of all things

ARISTARCHUS

• 310-230 BCE
• He proposed a heliocentric model of the solar system
• He tried to measure the distance to moon and sun

PTOLEMY

• 100-170 CE
• He believed that a celestial body didn't travel in a in circle
• Retrograde motion

NICOLAUS COPERNICUS

• 1473-1543
• Data had changed since the time of Ptolemy
• So he made a better version of the geocentric model(geocentric)
• Circular orbits

JOHANENAS KEPLER

• 1571-1630
• He formulated the Kepler laws
• His law states that planetary orbits are ellipses with the sun at one focus
• Kepler telescope

GALILEO GALILEI

• 1564-1642
• He made improvements to to the newly invented telescope
• He also observed moons that are now known as the Galilean satellites

ISAAC NEWTON

• 1643-1727
• He first scientists to describe of gravity behaves
• He formulated the law of universal gravitation

EDWIN HUBBLE

• 1889-1953
• He said that there were more galaxies then the milky ways

GEOCENTRIC MODEL

HELIOCENTRIC MODEL