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

Planets

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

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

The changing Number of planets in our solar system

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

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

Dwarf planets ceres Pluto Haumea makemake Eris

Planets and dwarf planets

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

Who Killed Pluto?

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

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

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

Formation of earth’s moon

Questions?

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