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Bit of Administration …. • Reading – BSNV Chaps. 9 and 15 • No Mathieu office hours today (Monday)! • Additional observations for Lab 2, through April 5 – Due April 7 in lecture or April 9 at Mathieu office • 12-week exam in two weeks - April 12, 7:15 pm – Review session, Sunday, April 11, 6:30 pm The Solar System • A Sense of Scale Around Earth Around Europe 0.1 Distance to Moon Distance to North America The Solar System • A Sense of Scale The Solar System • A Sense of Scale The Solar System • Inventory • Sun 99.85% by mass • Planets 0.1 % by mass • Satellites and Rings • Asteroids • Comets • Meteroids • Dust • Solar Wind (ionized gas) The Solar System • Inventory - “Sedna” The Solar System • General Characteristics of Major Planets - Dynamical • Nearly circular orbits (Mercury and Mars most eccentric) The Solar System • General Characteristics of Major Planets - Dynamical • Nearly circular orbits (Mercury and Mars most eccentric) • All orbit within 10o of Earth’s orbital plane The Solar System • General Characteristics of Major Planets - Dynamical • Nearly circular orbits (Mercury and Mars most eccentric) • All orbit within 10o of Earth’s orbital plane • All revolve in the same direction • All rotate in the same direction (except Venus) The Solar System • General Characteristics of Major Planets - Radius The Solar System • General Characteristics of Major Planets - Age • Earth - Oldest rocks 3.9 billion yr (4.5 billion yr inferred) • Moon - 4.5 billion yr • Meteorites - 4.6 billion yr • Sun - 4.6 billion (theoretical) • Universe - 12 billion yr The Solar System • General Characteristics of Major Planets - Physical Properties Location Size Mass Density Appearance Composition Terrestrial 7 Giant Satellites Jovian Inner Small (104 km) 0.1 - 1.0 MEarth 5 gm cm-3 Rock with craters, volcanos Heavy elements Outer Small (4000 km) 0.01 MEarth 2-3 gm cm-3 Rock, ice with craters, volcanos Heavy elements, ices Outer Large (105 km) 15 - 300 MEarth 1 gm cm-3 Gaseous, with rock cores Hydrogen, helium Notes: 1) Densities: Rock = 3 gm cm-3, Water = 1 gm cm-3 2) Composition of Sun and Universe by numbers of atoms: all else Jupiter94% H, 6% He, 2%Saturn Uranus Mercury Io Venus Europa Earth Ganymede Nepture Mars Callisto The Formation of the Solar System The Formation of the Solar System • Interstellar Clouds By Mass • 73% Molecular Hydrogen • 25%Atomic Helium • 2% Dust (Metals) ConcepTest! The Taurus clouds are thought to be rather cold, with temperatures of perhaps 30 K. If you wanted to test this hypothesis by looking for light emitted by the Taurus clouds, in what wavelength would you want to observe? A) X-ray B) Ultraviolet C) Optical D) Infrared E) Radio The Formation of the Solar System • Dense Molecular Cores (“Bok Globules”) • ≈ 1 Mo • ≈ 50,000 AU • ≈ 10 oK The Formation of the Solar System The Formation of the Solar System • Protoplanetary Disks • ≈ 0.01 Mo • ≈ 100 AU • ≈ 3000 -> 10 oK The Formation of the Solar System The Formation of the Solar System • Condensation Sequence • Condensation Temperature Temperature at which Solid T > 50 oK Gas T > 200 oK T > 1000 oK Hydrogen (H) Helium (He) Gas Gas Gas H20, Methane (CH4) CO2, Ammonia (NH3) Ice Gas Gas Iron (Fe), Silicon (Si) Metal Compounds Rock Rock Gas The Formation of the Solar System • Condensation Sequence M 1000 K No Grains V Rock Grains E M J 200 K Rock, Ice Grains The Formation of the Solar System The Formation of the Solar System • Grain Collisions ==> Planetesimals (100 km) random 100 km The Formation of the Solar System • Planetesimal Accretion ==> Rocky Planets and Jovian Cores gravity The Formation of the Solar System • Gas Accumulation ==> H and He onto Jovian Cores gravity Protomoons ConcepTest! Most comets have orbits that take them well beyond Jupiter. You would expect their composition to be: A) Rocks and heavy elements only B) Rocks and ices only C) Rocks, ices, and hydrogen and helium The Formation of the Solar System The Formation of the Solar System • Dispersal of Hydrogen and Helium Gas • Solar Wind? • Jets?