FAMOUS ASTRONOMERS

ARISTOTLE

• Aristotle lived around 384-322 B.C.E
• Greek philosopher
• He thought the earth was in the center of everything.
• Positions of the stars would change as earth moves.

ARISTARCHUS

• Aristarchus lived around 310-230 B.C.E
• He attempted to measure the distance between the moon and the sun.
• He was a Greek Astronomer and mathematician.

PTOLEMY

• Ptolemy lived around 100-170 C.E
• He was an astronomer, geographer, and mathematician
• Lived in Alexandria Egypt
• The planets moved on small circles that in turn moved on larger circles.

COPERNICUS

• Copernicus lived around 1473-1543
• He thought that ptolemy's model of the solar system was to complicated.
• He used wheels-on-wheels
• He changed Ptolemy's model alittle.

KEPLER

• Kepler lived around 1571-1630
• He was a German Mathematician
• He realized that requiring planetary motions to be exactly circular didnt fit the observations perfectly
• Kepler had 3 laws

KEPLER'S FIRST LAW

• Planetary orbits are ellipses with the sun at one focus

KEPLER'S SECOND LAW

• Planets move faster in their orbits when closer to the sun

KEPLER'S THIRD LAW

• The distance of a planet from the sun to the time it takes to go once around its
• .......orbits

GALILEO

• Galileo lived around 1564-1642
• He made significant improvements to the newly invented telescope
• He observed the moons IO, Europa, Callisto. And Ganymede orbiting Jupiter

ISAAC NEWTON

• He lived around 1643-1727
• Newtons law of universal gravitation
• It states that any two bodies in the universe attract each other with a force.

EDWIN HUBBLE

• He lived around 1889-1953
• He found out that space is constantly expanding

GEOCENTRIC

• Having the Earth as the center
• Aristotle created it
• Ptolemy developed a detailed geocentric model

HELICENTRIC

• Earth and the other planets orbit the sun
• Aristarchus reported to have proposed a heliocentric model of the solar system
• Copernicus made a heliocentric model
• Galileo invented a newly telescope