1. Warm-Up: May 10, 2016 Write down your answer to each of the following:
What is a planet?
How many planets are there?

2. Planets

3. In the Past…
Any “large enough” object orbiting the sun was considered a planet
What does “large enough” really mean?
In 2006, the international astronomical union answered that question

4. What is a planet? A 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 (nearly round) shape, and
has cleared the neighborhood around its orbit

5. The changing Number of planets in our solar system

6. exoplanets On may 12, 2011, there were 431 discovered exoplanets.

7. Dwarf planet definition
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 (nearly round) shape

8. Dwarf planets
ceres
Pluto
Haumea
makemake
Eris

9. Planets and dwarf planets

10. The Rise and Fall of Pluto
1930: Discovered by Clyde Tombaugh at Lowell Observatory
1990’s: Other Kuiper Belt objects started to be discovered
2005: A Kuiper Belt object larger than Pluto is discovered (later named Eris)
August 24, 2006: The International Astronomical Union (IAU) formally defines “planet,” and demotes Pluto to “dwarf planet” status

11. Who Killed Pluto?

12. Why Pluto Had It Coming It’s too small – smaller than our moon
It has a strange orbit
It crosses Neptune’s orbit
It’s just one of many objects in its area – Kuiper Belt is similar to the asteroid belt

14. Moons A moon is an object that orbits something besides a star
Moons are also called “satellites”
Earth’s moon was likely formed when a mars-sized object collided with earth
The 8 planets in our solar system have over 150 moons

15. Names of moons Earth: Moon Mars: phobos, deimos
Jupiter: Metis, Adrastea, Amalthea, Thebe, Io, Europa, Ganymede, Callisto, Themisto, Leda, Himalia, Lysithea, Elara, Carpo, Euporie, Orthosie, Euanthe, Thyone, Mneme, Harpalyke, Hermippe, Praxidike, Thelxinoe, Helike, Iocaste, Ananke, Eurydome, Arche, Autonoe, Pasithee, Chaldene, Kale, Isonoe, Aitne, Erinome, Taygete, Carme, Sponde, Kalyke, Pasiphae, Eukelade, Megaclite, Sinope, Hegemone, Aoede, Kallichore, Callirrhoe, Cyllene, Kore, Herse, and 12 unnamed
Saturn: Pan, Daphnis, Atlas, Prometheus, Pandora, Epimetheus, Janus, Aegaeon, Mimas, Methone, Anthe, Pallene, Enceladus, Telesto, Tethys, Calypso, Helene, Dione, Polydeuces, Rhea, Titan, Hyperion, Iapetus, Albiorix, Bebhionn, Erriapo, Tarvos, Kiviuq, Ijiraq, Paaliaq, Siarnaq, Tarqeq, Narvi, Bestla, Skathi, Skoll, Hyrokkin, Bergelmir, Farbauti, Kari, Phoebe, Griep, Jarnsaxa, Mundilfari, Suttungr, Hati, Thrymr, Aegir, Fenrir, Surtur, Loge, Ymir, Fornjot, and 10 unnamed
Uranus: Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda, Perdita, Puck, Mab, Miranda, Ariel, Umbriel, Titania, Oberon, Francisco, Caliban, Stephano, Trinculo, Sycorax, Margaret, Prospero, Setebos, Ferdinand
Neptune: Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, Nereid, Halimede, Sao, Laomedeia, Psamanthe, Neso

17. Formation of earth’s moon

18. Questions?

19. Work Time
You have the rest of class to work on the assignment due next class