ASTRONOMERS

ARISTOTLE

• Thought the earth was the center of all things
• He though the earth went around the sun
• He was a Greek philosopher

ARISTARCHUS

• Greek astronomer and mathematician
• Proposed a heliocentric model of the solar system
• Attempted to measure the distance from earth to the sun

PTOLEMY

• Astronomer, mathematician, and geographer.
• He wrote a book based on observations of the planets.
• Developed a geocentric model that was used for 14 years

COPERNICIOUS

• He adopted Ptolemys idea that planetary paths should be perfect circles
• He used a wheels on wheels system
• His model fit better than Ptolemys.

KEPLER

• German mathematician and astronomer
• Realized that the planets motions weren't perfect circles
• He found 3 principals which are today known as Kepler's laws

GALILEO GALILEI

• He made significant improvements to the telescope
• He observed the moon, lo, Europa, Callisto, and Ganymede
• His observations showed that earth wasn't the only thing that orbited.