Link to directions: http://www.astrosociety.org/education/publication s/tnl/70/pluto.html#10 Link to images: http://www.astrosociety.org/education/publication s/tnl/70/solarsystemcards.pdf
SURVEY Do you think Pluto should be a planet? YESNO Image: Hubble Space Telescope
Read this article Hubble Observations of Ceres and Pluto http://www.astrosociety.org/education/public ations/tnl/70/pluto.html http://www.astrosociety.org/education/public ations/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
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
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.
Then Uranus was discovered (1781) Total Number of Planets = 7
Then Astraea was discovered (1845) Number of planets = 12 At this point the definition for planet is still “Wandering Star”.
Moon diameter compared to the first 10 asteroids to be discovered
Next came Neptune (1846) Total number of planets = 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. orbitthe Sun planetcomet Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. dwarf planetsasteroids trojanscentaursKuiper belt trans-Neptunian objects  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of its discovery until 1851 it was considered to be a true planet).Ceres The orbits of more than 570,000 objects have been archived at the Minor Planet Center. Minor Planet Center 
Video (4:45 minutes) http://www.universetoday.com/13573/why- pluto-is-no-longer-a-planet/
International Astronomical Union (IAU) Planets Dwarf Planets Small Solar System Bodies
Ceres and Pluto: Dwarf Planets as a New Way of Thinking about an Old Solar System Activity Link:
Definition A planet is a celestial body that 1.Is in orbit around the Sun (or other star if speaking about exoplanets) 2.Has sufficient mass for its self- gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (round) 3.Has cleared the neighborhood around its orbit. 4.Is NOT a satellite Examples
Definition A dwarf planet is a celestial body that 1.Is in orbit around the Sun 2.Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape 3.Has NOT cleared the neighborhood around its orbit 4.Is NOT a satellite Examples: Ceres, Pluto, Eris Click the image to go to Mike Brown’s Dwarf planet page
Definition An asteroid is a celestial body that: 1.Orbits the Sun inside the orbit of Jupiter 2.DOES NOT have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape (IT IS NOT ROUND) 3.HAS NOT cleared the neighborhood around its orbit 4.IS NOT a satellite Examples
Click on the Image to link to the Deep Impact mission page
Definition All other objects, except satellites, orbiting the Sun Examples Most asteroids Most Trans-Neptunian Objects (TNO’s) Comets Other small bodies
Pluto’s changing landscape http://hubblesite.org/news center/archive/releases/201 0/06/video/a/ http://hubblesite.org/news center/archive/releases/201 0/06/video/a/ Pluto is: 1.Dwarf Planet 2.Kuiper Belt Object 3.Trans-Neptunian Object 4.Plutoid Link here to PlutoToday.com http://www.plutotoday.com/
Pluto’s fifth moon! Click on the image to view a short video of the motion of the moons.
Click on the image to visit the NEW HORIZONS mission webpage
Use the Internet to Research Earth Ceres Vesta Pluto 1.www.nineplanets.orgwww.nineplanets.org 2.http://ssd.jpl.nasa.gov/http://ssd.jpl.nasa.gov/
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? EarthCeresVestaPluto 5.52.02.42.0
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.
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.
The more that we learn about our solar system, the more our classification schemes are challenged to include new discoveries. New Horizons IBEXNEAR
Neil Degrasse Tyson on Pluto New York Public Radio (5:10 minutes) http://www.youtube.com/watch?v=4Rwe54vtv UA PBS Movie (The Pluto Files 52:52 minutes) http://www.pbs.org/wgbh/nova/space/pluto- files.html
Allen Stern’s thoughts on Pluto (Planetary Scientist) Nova Podcast (6:30 minutes) http://www.pbs.org/wgbh/nova/space/defense- pluto.html Conclusion for Pluto – NOT A PLANET, NOT EVEN THE LARGEST OF THE DWARF PLANETS, BUT SITS A CLOSE SECOND! http://www.pbs.org/wgbh/nova/space/defense- pluto.html
Mike Brown – CalTech Astrophysicist http://www.youtube.com/ watch?v=C9pXpXAl8m8&f eature=related
Facts and Quizzes Interesting Facts about our Dwarf Planets http://www.youtube.com/watch?feature=endscreen&v=Ho5F EyftFss&NR=1 Quiz on Pluto http://www.space.com/16537-pluto-quiz-dwarf-planet- moons.html Dwarf Planet Quiz 1.http://www.astronomyquiz.info/dwarf-planets-quiz.htmlhttp://www.astronomyquiz.info/dwarf-planets-quiz.html 2.http://www.funtrivia.com/playquiz/quiz3249712533f30.ht mlhttp://www.funtrivia.com/playquiz/quiz3249712533f30.ht ml
QUIZ IMAGE 1 INFORMATION This object has not cleared out its neighborhood orbit.
Image 2 INFORMATION This object is in an orbit around the Sun between the orbits of Mars and Jupiter.
Image 3 INFORMATION This object is in an orbit around the Sun between the orbits of Mars and Jupiter.
Image 4 INFORMATION This object orbits the Sun past Neptune’s average distance from the Sun
Image 5 NFORMATION This object contains more than 90% of the total mass in its path around the sun
Image 6 INFORMATION This object is in an orbit around the Sun between the orbits of Mars and Jupiter.
Image 7 INFORMATION This object would be rounded but its extreme rotation causes it to bulge.
Image 8 INFORMATION This object’s orbit is highly eccentric.
Image 9 INFORMATION This object orbits the Sun at an average distance of.3 AU
Image 10 INFORMATION This object is the most distant of 8 objects in its classification.