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http:// www.youtube.com/watch?v=BYcTN8H7ysw. Good Planets are hard to find. Classifying Objects in the Solar System. Activity 1: Sorting the Solar System. Link to directions: http://www.astrosociety.org/education/publications/tnl/70/pluto.html#10 Link to images:

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  1. http://www.youtube.com/watch?v=BYcTN8H7ysw Good Planets are hard to find

  2. Classifying Objects in the Solar System

  3. Activity 1: Sorting the Solar System Link to directions: http://www.astrosociety.org/education/publications/tnl/70/pluto.html#10 Link to images: http://www.astrosociety.org/education/publications/tnl/70/solarsystemcards.pdf

  4. SURVEY Do you think Pluto should be a planet? Image: Hubble Space Telescope

  5. Read this article Hubble Observations of Ceres and Pluto • http://www.astrosociety.org/education/publications/tnl/70/pluto.html There is a handout that goes with this article titled: Hubble Observations of Ceres and Pluto. You can find it in the folder titled Classifying Objects in the Solar System

  6. The Original Definition of a Planet Planet is derived from the Greek word αστήρ πλανήτης (Wandering Star) This was anything that wandered in the sky differently that the fixed stars

  7. How many planets are there? Geocentric Model (Early Greek) Total Number of Planets = 7 Heliocentric Model (1550) Total number of Planets = 6 Due to Reclassification of Earth, Moon and Sun This was all that could be seen by the unaided eye.

  8. Then Uranus was discovered (1781) Total Number of Planets = 7

  9. Total number of planets = 11

  10. Then Astraea was discovered (1845) Number of planets = 12 At this point the definition for planet is still “Wandering Star”.

  11. Moon diameter compared to the first 10 asteroids to be discovered

  12. Next came Neptune (1846) Total number of planets = 13

  13. Reclassification of 1851 • 1851 – 15 asteroids • A minor planet is an astronomical object in direct orbit around the Sun that is neither a dominant planet nor originally classified as a comet. • Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects.[1] • The first minor planet discovered was Ceres in 1801 (although from the time of its discovery until 1851 it was considered to be a true planet). • The orbits of more than 570,000 objects have been archived at the Minor Planet Center.[2]

  14. How are the planets spaced out? Use your Pocket Solar System to roughly describe how the planets in our solar system are spaced out? Does the spacing seem to follow a pattern?

  15. Just worth a note: Titus-Bode Law

  16. What is a Planet???

  17. Why Pluto is No Longer a Planet? Video (4:45 minutes) http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/

  18. International Astronomical Union (IAU) • Planets • Dwarf Planets • Small Solar System Bodies RESOLUTION B5

  19. Ceres and Pluto: Dwarf Planets as a New Way of Thinking about an Old Solar System Activity Link:

  20. Planets ~ There are 8 Definition Examples A planet is a celestial body that • Is in orbit around the Sun (or other star if speaking about exoplanets) • Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (round) • Has cleared the neighborhood around its orbit. • Is NOT a satellite

  21. Dwarf Planets Definition Examples: Ceres, Pluto, Eris A dwarf planet is a celestial body that • Is in orbit around the Sun • Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape • Has NOT cleared the neighborhood around its orbit • Is NOT a satellite Click the image to go to Mike Brown’s Dwarf planet page

  22. Notable Dwarfs Eris by Hubble Eris Orbit

  23. Eris Orbit Eccentricity and Inclination Eris Discovery (3 frames over 3 hours)

  24. Notable Dwarfs Haumea Sedna

  25. Asteroids Definition An asteroid is a celestial body that: Examples • Orbits the Sun inside the orbit of Jupiter • DOES NOThave sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (IT IS NOT ROUND) • HAS NOT cleared the neighborhood around its orbit • IS NOT a satellite

  26. Comparison of Astroids

  27. Mars and asteroids: size comparisons

  28. Click on the image to visit the NEAR mission webpage

  29. Dwarf Planet or Asteroid? Ceres Vesta

  30. Click on the image to visit the DAWN mission website

  31. Trans-Neptunian Objects (TNO’s) any objects in the Solar System that orbits the Sun at a greater average distance than Neptune. TNO’s are

  32. Plutoids A Plutoid (or ice dwarf)is • trans-Neptunian object • dwarf planet: that is, a body orbiting beyond Neptune that is large enough to be rounded in shape.

  33. Comets

  34. Stardust

  35. Click on the Image to link to the Deep Impact mission page

  36. Small Solar System Bodies Definition Examples Most asteroids Most Trans-Neptunian Objects (TNO’s) Comets Other small bodies • All other objects, except satellites, orbiting the Sun

  37. So What is Pluto? Pluto’s changing landscape Pluto is: Dwarf Planet Kuiper Belt Object Trans-Neptunian Object Plutoid Link here to PlutoToday.com http://www.plutotoday.com/ • http://hubblesite.org/newscenter/archive/releases/2010/06/video/a/

  38. Pluto’s fifth moon! Click on the image to view a short video of the motion of the moons.

  39. Click on the image to visit the NEW HORIZONS mission webpage

  40. Originally You thought a Planet must have… LAYERS WATER Magnetic Fields Orbits Atmospheres SURFACE Size or Shape Core Location Moons GRAVITY

  41. Use the Internet to Research Earth Ceres Vesta Pluto www.nineplanets.org http://ssd.jpl.nasa.gov/

  42. One Comparison Earth has a relatively high density compared to the other three objects The Earth is a planet and the other three are not, maybe density should be considered when classifying planets/non planets. Question: How does density affect the other characteristics of a planet?

  43. Should Pluto be a Planet???

  44. Conclusions The International Astronomical Union has chosen one characteristic (the extent to which a body has cleared its orbital neighborhood of other bodies) as the distinguishing characteristic of a planet versus a dwarf planet, there are many other characteristics to consider.

  45. Conclusions Many planetary scientists would rather see a definition that focused more on characteristics of the body itself rather than where it is or what is near it.

  46. New Horizons The more that we learn about our solar system, the more our classification schemes are challenged to include new discoveries. NEAR IBEX

  47. Neil Degrasse Tyson on Pluto New York Public Radio (5:10 minutes) http://www.youtube.com/watch?v=4Rwe54vtvUA PBS Movie (The Pluto Files 52:52 minutes) http://www.pbs.org/wgbh/nova/space/pluto-files.html

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