Bell Ringer 9/8

1. Bell Ringer 9/8 • OPINION QUESTION – How do you believe the solar system was formed?

2. Chapter 28 Formation of the Solar System

3. Big Bang Theory • Theory that universe began as a point and has been expanding ever since

4. Solar System • Theories rely on observation and data from probes sent into space • Theories explain • Shape of solar system • Differences between planets • Nature of planetary surface

5. Stars & Planets form from interstellar clouds, which exist in space between the stars http://www.astrographics.com/GalleryPrints/Display/GP0069.jpg

6. Orion Cloud http://www.daviddarling.info/images/interstellar_cloud.jpg

7. Triangulum.nebula http://upload.wikimedia.org/wikipedia/commons/thumb/7/74/Triangulum.nebula.full.jpg/563px-Triangulum.nebula.full.jpg

8. Interstellar Clouds • Consist mostly of hydrogen and helium gas with small amounts of other elements and dust • Dust makes clouds look dark by blocking light • Dust also reflect starlight and makes clouds look bright

9. How astronomers believe solar system formed • Density of interstellar gas is low • Gravity slowly draws matter together until the matter is concentrated enough to form stars and planets

10. Interstellar Cloud • Collapse of cloud begins slowly but gradually gets faster • Cloud becomes more dense at center • If rotating, the cloud spins faster as it contracts, due to centripetal force. • (DEMONSTRATION)

11. Interstellar Cloud • Interstellar cloud that formed our solar system collapsed into a rotating disk of dust and gas • Concentrated matter at the center acquired enough mass to form the Sun • Remaining matter gradually condensed to form planets

12. Interstellar Cloud • Temperature varied greatly with location • Different elements and compounds condensing, affected distribution of elements on the planets • Depending on their distance from the Sun

13. Planetesimals • Space objects built of solid particles that can form planets through collisions

14. Large Planets • First to develop was Jupiter • Increased in size through the merging of icy planetesimals that contained mostly lighter elements • Saturn and the other gas giants formed same way • Not as large because Jupiter collected so much material

15. Inner Planets • Planets that formed near the young Sun • Composed primarily of elements that resist vaporization (didn’t become gassy) • Rocky and dense

16. Debris • Material that remained after the formation of the planets and satellites • Some became icy objects known as comets • Others formed rocky planetesimals known as asteroids • Thousands of asteroids have been detected in the asteroid belt, which lies between Mars and Jupiter.

17. In-Class Assignment/Homework

18. Bell Ringer 9/9 • Explain in your own words how scientists believe our sun formed

19. 28.1 B Models of Solar System

20. Aristotle • 3rd century BC • Geocentric: Earth-centered solar system • did not explain retrograde (backward) motion of planets

21. Aristotle

22. Ptolemy • 3rd century AD • Planets revolve around Earth in circles • epicycles to explain retrograde motion

23. Ptolemy

24. Retrograde motion • The apparent backward movement of a planet • The changing angles of view from Earth create the apparent retrograde motion of Mars.

25. a Danish astronomer Made accurate observations of the planets’ positions Tycho Brahe http://honolulu.hawaii.edu/distance/sci122/Programs/p10/Brahe.jpg

26. Nicolaus Copernicus http://www.cgirb.com/images/copernicus.jpg

27. Copernicus • 16th century • Heliocentric: sun-centered model • Earth and planets orbit the sun in the same direction, but at diff. speeds and distances

28. Copernicus • Solves problem of retrograde motion • 1700’s Galileo proves this with telescope

29. In-Class Assignment/Homework • Ancient Astronomers WKT

30. Bell Ringer 9/10 • Who said our solar system was geocentric? • Who said it was heliocentric?

31. Kepler • 17th century • Used observations of his teacher, Brahe, to explain planetary motion.

32. Johannes Kepler http://www.nasa.gov/images/content/65879main_kepler-portrait-330-427.jpg

33. Kepler • Each planet orbits the Sun in a shape called an ellipse, rather than a circle • An ellipse is an oval shape that is centered on two points. http://ca.geocities.com/web_sketches/ellipse_notes/ellipse_arc_length/ellipse_eccentric_angle.gif

34. Kepler’s 1st Law • Law of ellipses : planets orbit the sun not in a circle, but in an ellipse. • Astronomical unit: average distance between the sun and the earth.

35. Kepler’s 2nd Law • Law of equal areas: Earth moves fastest when closest to the sun • Line from the center of a planet sweeps through equal areas in equal periods of time.

36. Kepler’s 3rd Law • Law of periods: Relationship between distance from the sun and the orbit period. • Orbit period: the time required for the planet to make one revolution around the sun.

37. Galileo Galilei http://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Galileo.arp.300pix.jpg/300px-Galileo.arp.300pix.jpg

38. Galileo • First person to use a telescope to observe the sky • Discovered that four moons orbit the planet Jupiter • Proved that not all celestial bodies orbit Earth and Earth was not necessarily the center of the solar system

39. Isaac Newton

40. Isaac Newton • Inertia: objects want to move in a straight line at constant speed until acted upon by an outside force • Gravity: force that pulls them out of that straight line

41. In-Class Assignment/Homework • WKT 87 – Kepler’s La • #3 = Major axis – line that runs along diameter of ellipse, Semimajor axis – average distance between sun and the planet • #4 = Eccentricity – shape of the planet’s elliptical orbit