ASTRONOMY

ARISTOTLE

• 384-322 BCE
• Believed the center of all things was the earth.
• Created a model of the moon, sun, planets, and stars surrounding the Earth.
• Produced the idea of a parallax in space.
• Said that the earth was round in his geocentric model.

ARISTOTLE MODEL

ARISTARCHUS

• About 310-230 BCE
• Created a not widely accepted model of the solar system .
• Attempted to measure the distance to the moon and sun using geomery.
• His Heliocentric Model of the earth was an extension of Aristotle's Model.

GEOMETRIC WAY ARISTARCHUS USED TO MEASURE THE DISTANCE

PTOLEMY

• About 100-170 CB
• Author of Almagest, a book on observations of planets.
• Created a geometric model of space.
• His model expressed a "wheels on wheels" (retrograde motion) system.
• In this system planets moved on smaller circle which moved on larger ones.

PTOLEMAIC MODEL (GEOCENTRIC)

• Model that uses the earth as the center.

COPERNICUS

• 1473-1543
• Changed Ptolemy's model of the solar system.
• Created a new model in which the sun was the center of everything.
• The heliocentric model of copernicus was the first step of the modern solar systems.

COPERNICAN MODEL (HELIOCENTRIC)

• Model in which earth and other planets orbit the sun.

KEPLER

• 1571-1630
• Created three principals called the Kepler's Laws.
• 1. The path of the planets around the sun is elliptical in shape, with the center of the sun being located at one focus.
• 2. Planets move faster in their orbit when closer to the sun.
• 3. Relates to the distance of a planet from the sun to the time it takes to go around its orbit.

ELLIPSES: KEPLER'S FIRST LAW

GALILEO

• 1564-1642
• Made many improvements to the newly constructed telescope.
• He used his improved telescope to study planets and moons (Galilean Satellites).
• His observations showed other planets or objects, besides earth, could be orbited.
• He also found that Venus was similar to the earth's moon.

GALILEO TELESCOPE

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