The document defines planets, dwarf planets, and plutoids. Planets orbit the sun, are round in shape, and have cleared their orbit. Dwarf planets also orbit the sun and are round, but have not cleared their orbit. Plutoids are dwarf planets found beyond Neptune's orbit. Examples are provided of Earth, Pluto, and Ceres to illustrate how they fit or do not fit these categories.

1. Solar Systems 1_ New Definitions... By: Christian Hassler_ Next Slide

2. What is a Planet? As defined by the International Astronomical Union, a planet is a celestial body that… a) Is in orbit around the sun b) has sufficient mass for its self- gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape c) has cleared the neighborhood around its orbit Next Slide

3. For Example... Is Earth a planet? Is it in orbit around the sun? Does it have a nearly round shape? Has it cleared the area around it’s orbit? Yes, Earth is a planet Next Slide

4. What is a dwarf planet? As defined by the International Astronomical Union, a dwarf planet, like a planet must… a) Be in orbit around the sun b) have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape Next Slide

5. What is a dwarf planet? Unlike a planet, a dwarf planet must… c) Have not cleared the area around its orbit d) not be a satellite Satellite: a celestial body that orbits a planet Next Slide

6. For Example... Is the moon a dwarf planet? Is it in orbit around the sun? Does it have a nearly round shape? Has it cleared the area around its orbit? Is it not a satellite? No, the moon is not a dwarf planet Next Slide

7. For Example... Is Pluto a dwarf planet? Is it in orbit around the sun? Does it have a nearly round shape? Has it not cleared the area around its orbit? Is it not a satellite? Yes, Pluto is a dwarf planet Next Slide

8. What is a plutoid? Plutoids are dwarf planets in orbit around the Sun at a semi-major axis greater than that of Neptune ? ? ? This is actually simpler than it sounds… Plutoids are defined the same as dwarf planets, except plutoids are found “outside” of Neptune. These are planets These are dwarf planets Dwarf planets to this side of Neptune are plutoids Plutoids Next Slide

9. For Example... Is Ceres a plutoid? Is it in orbit around the sun? Does it have a nearly round shape? Has it cleared the area around its orbit? Is it not a satellite? No, Ceres is not a plutoid Next Slide Is it in orbit around the Sun at a semi-major axis greater than that of Neptune

10. Review What do planets, dwarf planets and plutoids have in common? They all have not cleared the area around their orbit. They all must orbit the sun Sorry, Try Again Correct! Next Slide Planets, dwarf planets, and plutoids all must orbit the sun, otherwise they would be moons. Select the Correct Answer

11. Review Where must plutoids be located? In the asteroid belt Beyond Neptune Sorry, Try Again Correct! Next Slide Plutoids are dwarf planets in orbit around the Sun at a semi-major axis greater than that of Neptune Select the Correct Answer

12. http://solarsystem.nasa.gov/planets/profile.cfm?Object=Dwarf http://solarsystem.jpl.nasa.gov/planets/index.cfm Credits Thank You for Watching!