Astronomer Project

ARISTOTLE (384-322 BCE)

• A Greek Philosopher
• Thought earth was the center of all things
• Knew that earth went around the sun
• Proposed the positions of stars changed because earth moves
• Discovered the apparent shift in movements, the "parallax"

Aristarchus (310-230 BCE)

• A Greek astronomer and mathmatition
• Proposed a heliocentric model of the solar system
• The model wasn't wildly accepted
• Attempted to measure distances to the moon and sun
• Was important in the use of observation and geometry

Ptolemy (100-170 CE)

• Wrote a book based on observations dating over 800 years ago
• Developed a detailed geocentric model used for 14 centuries
• Believed that a celestial body traveled at a constant speed in a circle
• In his model the planets turned on "wheels"
• His wheel system is the best model system we've had

Copernicus (1473-1543)

• Developed first detailed heliocentric model
• Adopted Ptolemy's idea that planets travel in perfect circles
• Used the "wheel-on-wheels" system
• His heliocentric model is often seen as a great step in modern astronomy
• Back in his time, data was still seen with only the naked eye, or what they had

Kepler (1571-1630)

• Realized that planetary motions were not a perfect circle
• Tried other paths and found that eclipses were the closest
• Created 3 principals know today as Kepler's Laws
• They state that they travel faster by the sun and the distance it takes
• The first Law states that planetary eclipses are with the sun at one focus

Galileo (1564-1642)

• Approached questions that we today call scientific methods
• Made significant improvements to the newly invented telescope
• Today the moons he observed are called Galilean satellites
• His observations showed that earth wasn't the only thing that orbited
• He also observed Venus and how it went through phases similar to the moon