ASTRONOMERS

ARISTOTLE

• Lived 384-322 BCE
• Believed the Earth was surround by everything.
• Believed in a shift called parallax

ARISTARCHUS

• Lived 310-230 BCE
• Made a heliocentric model of the solar system
• Attempted to measure the relative distances of the moon and sun

PTOLEMY

• Lived 100-170 CE
• Made a geocentric model of the universe
• Believed planets moved in small circles
• Believed the celestial body moved at a constant speed in a perfect circle

COPERNICUS

• Lived 1473-1543
• Made first detailed heliocentric model
• Believed planets moved in small circles

KEPLER

• Lived 1571-1630
• Realized planets do not move perfectly circular
• Created three Kepler laws

KEPLERS FIRST LAW

• There are elliptical orbits for planets
• Each planet orbits the sun in an eclipse with the sun

KEPLERS SECOND LAW

• In aphelion a planet moves slower
• In perihelion a planet moves faster

KEPLERS THIRD LAW

• The the orbital period is proportional to a planets distance to the sun
• Law is true for each planet

GALILEO

• Made improvements to the telescope
• Found Earth was not the only subject that could orbit
• Found Venus went through phases similar to earths moon.

ISAAC NEWTON

• Lived 1643-1727
• Popular for work on forces
• Created Newtons Laws

HUBBLE

• Lived 1859-1953
• Determined the universe is expanding
• Law that determined the universe was expanding later became Hubble's Law