ASTRONOMERS

ARISTOTLE

• Greek philosopher
• (384-322 BCE)
• Observed the earth is round

ARISTARCHUS

• (312-230 BC)
• Tried to measure distance to moon and sun
• Professed a sun centered view of the solar system
• He was dismissed by Aristotle

CLAUDIUS PTOLEMY

• (100-170 AD)
• Geocentric model
• Tried to explain the retrograde motion of planets
• He used motions for planets
• They appeared to move backwards in the sky

NICOLAUS COPERNICUS

• (1473-1543)
• Developed the first detailed heliocentric model of solar system
• He used the "wheels on wheels" system
• Adopted Ptolemys idea that the planetary paths should be perfect circles

JOHANNES KEPLER

• (1571-1630)
• He formatted three principles which are known for keplers laws
• He realized that requiring planetary motions didn't fit observations
• He was a German mathematician and astronomer

GALILEO GALILEI

• (1564-1642)
• He approached questions in the fashion called scientific method
• He observed the moons in Io, Europa, Callisto, and Ganymede orbiting Jupiter
• He also observed that Venus went through phases similar to the phases of earths moon
• Was an Italian mathematician, physicist, and astronomer

ISAAC NEWTON

• English physicist and mathematician
• (1643-1727)
• Discovered gravity
• Most influential scientist of all time

EDWIN HUBBLE

• American astronomer
• (1889-1953)
• Created the Hubble space telescope

GEOCENTRIC SOLAR SYSTEM

• The earth is in the center with the other plants orbiting it

HELIOCENTRIC

• The model of the solar system where the sun is in the middle