ASTRONOMERS IN HISTORY

ARISTOTLE

• Was a Greek philosopher
• Thought Earth was the center of all things
• Created a model that had Earth in the center
• Lived from 384-322 BCE

ARISTARCHUS

• A Greek astronomer and mathematician
• Proposed a heliocentric model of solar system
• Attempted to measure the distances to the moon and sun

PTOLEMY

• Astronomer, geographer, mathematician
• His model was accepted for 1400 years
• His model was geocentric
• It allowed prediction of the motion of planets in the future

COPERNICUS

• A polish astronomer
• Aware of the heliocentric model of Aristarchus
• Used a "wheels on wheels" system
• Adopted Aristarchus idea that planetary oaths should be perfect circles
• His model seen as the first step in the development of modern models

KEPLER

• A German mathematician and astronomer that formulated three laws
• known today as Kepler's laws.
• First: planetary orbits are ellipses with the sun at one focus
• Second: planets move faster in their orbits when closer to the sun
• relates distance of planet from sun to the time it takes to go around once

GALILEO

• Created the scientific method
• Made improvement to today's telescope
• Io, Europa, Callisto, Ganymede are known as the Galilean satellites
• Observations showed that Earth not the only thing that could be orbited
• Gave support to the heliocentric model