1. Astrology vs. Astronomy Which one is science? astro - star -logy – study of -nomy – arrangement, law

2. Calendars – based on astronomical movements Day – Earth’s rotation (spinning) Month – moon orbits Earth (approx.) Year – Earth revolves around sun

3. Early Astronomers Ptolemy – thought Earth was center of the universe geo centric

4. Copernicus -determined that the Sun is the center of the solar system

5. Tycho Brahe – made very precise observations. Thought moon and sun revolved around Earth, but other planets around the sun.

6. Johannes Kepler Used Brahe data to determine that the planets revolve around the sun in elliptical orbits. The sun is not in the exact center.

8. Isaac Newton -described the force of gravity which depends on the mass of the objects and the distance between them -explained observations of other astronomers

13. Artificial Satellites Military Weather Communication