2. “Intro to Astronomy” §Terms You Need To Know! 1. Astronomy- The study of everything outside of the earth’s atmosphere. 2. Celestial Sphere - Imaginary sphere that surrounds Earth, in which all stars, planets and moons are attached to. 3. Zenith Point - The point directly above you in the sky. 4. Nadir Point - The point directly below in the sky. 5. Parallax - When an object is moving, the apparent motion you see when close objects move faster than far away objects.

3. §6. Rotation - An object spinning on its axis. §7. Revolution - One object orbiting around another object. §8. Geocentric Universe - Earth centered universe. §9. Heliocentric Universe - Sun centered universe. §10. AU - The distance from the Earth to the Sun. 93,000,000 million miles “History of Astronomy” §A. Geocentric People: §1. Plato: - Planetary objects moved in “God Paths” - Aristotle was his student.

4. §2. Aristotle: -Said the Earth didn’t move because he did not see parallax with the stars in the sky. B. Heliocentric People: §1. Copernicus: - One of the first people to teach the heliocentric universe model. - The Church let him go because he was working on calendar reform. §2. Tycho Brahe: - Studied the positions of many planets and stars. - Discovered the sky changed when he found a comet in the sky.

5. §3. Kepler: - Helped Tycho Brahe with mathematics. - Discovered the “ 3 Laws of Planetary Motion. §5. Newton: - Invented the telescope. - Discovered moons revolving around Jupiter. §4. Galileo: - Discovered the Laws of Gravity. - Discovered the 3 Laws of Motion. - Proved the heliocentric universe model.