Chapter Outline Earth and Other Planets The Formation of the Solar System Exploring the Solar System Chapter 16 Great Idea: Earth, one of the planets that orbit the Sun, formed 4.5 billion years ago from a great cloud of dust. Clues to the Origin of the Solar System The Formation of the Solar System Solar system Objects gravitationally bound to Sun Deduction of origin Observations Earth Space Clue #1: Planetary Orbits Features of solar system All planets orbit in same direction Orbits in same plane Most rotate in direction of orbit Clue #2: Distribution of Mass Most material within Sun Two types of planets Terrestrial planets Jovian planets Other objects Moons, asteroids, comets
The Nebular Hypothesis Nebular Hypothesis Cloud of dust and gas 99% H and He Collapse of nebula Planetary orbits Clumping of matter Planetesimals Temperature Basic Planet Categories Terrestrial planets Mercury Venus Earth Mars Jovian planets Jupiter Saturn Uranus Neptune Some Conclusions Planets formed at same time as Sun Planetary and satellite/ring systems are similar to remnants of dusty disks such as that seen about stars being born Planet composition dependent upon where it formed in solar system Nebular Condensation (protoplanet) Model Most remnant heat from collapse retained near center After sun ignites, remaining dust reaches an equilibrium temperature Different densities of the planets are explained by condensation temperatures Nebular dust temperature increases to center of nebula Nebular Condensation Physics Energy absorbed per unit area from Sun = energy emitted as thermal radiator Solar Flux = Lum (Sun) / 4 x distance 2 Flux emitted = constant x T 4 [Stefan-Boltzmann] Concluding from above yields T = constant / distance 0.5 Nebular Condensation Chemistry Molecule Freezing Point Distance from Center H 2 10 K >100 AU H 2 O 273 K >10 AU CH 4 35 K >35 AU NH 3 190 K >8 AU FeSO 4 700 K >1 AU SiO 4 1000 K >0.5 AU
Nebular Condensation Summary Solid Particles collide, stick together, sink toward center Terrestrials -> rocky Jovians -> rocky core + ices + light gases Coolest, most massive collect H and He More collisions -> heating and differentiating of interior Remnants flushed by solar wind Evolution of atmospheres The most abundant chemical element in the solar nebula A Uranium B Iron C Hydrogen D Helium E Lithium Pictorial View of Origins Pictorial View Continued HST Pictorial Evidence HST Pictorial Evidence
As a planetary system and its star forms the temperature in the core of the nebula A Decreases in time B Increases in time C Remains the same over time D Cannot be determined As a planetary system and its star forms the rate of rotation of the nebula A Decreases in time B Increases in time C Remains the same over time D Cannot be determined The Formation of Earth Planetesimals Combined (accretion) to form earth Great bombardment Meteors Growth of planet 20 metric tons per day Differentiation Differentiation Heat from collisions Dense material sank to center Lighter material rose to surface Structure Core Mantle Crust Crust and Us Earth s Interior - How We Know It
Which of the diagram represents the mantle of the Earth? A B C D E None of the above. Which of the diagram represents the outer core of the Earth? A B C D E None of the above. Energy transport from one region to another by the movement of material as in the mantle of the Earth is known as A chaos. B radiance. C conduction. D differentiation. E convection. The existence of earthquake shadow zones indicates that there is an abrupt change between the properties of the mantle and those of the core. Specifically, the transverse wave shadow zone shows that the outer core must be A solid. B liquid or semi-liquid. C gaseous. D similar to crustal material. E impossible to determine. The Formation of the Moon Large object (asteroid close to size of Mars) impacted earth Parts of mantle blown into orbit Moon formed from this material Planetary Idiosyncracies Cratering Mercury, Mars, Moon Few on Earth weathering Rotation Venus Earth s axis Uranus
The Evolution of Planetary Atmospheres Earth s atmosphere Early Outgassing Atmosphere was N 2, CO 2, H 2, & H 2 O Gravitational escape Living organisms All our observations of the Sun and planets have been made from the surface of the Earth. A True B False All planets and most of their moons orbit in the same direction around the Sun A True B False Almost all planets and moons rotate on their axes in the same direction as the planets orbit the Sun. A True B False What is the shape of our solar system? A spherical (like a ball) B flat (like a dish) C tubular (like a hot dog) The mass in our solar system is evenly distributed. A True B False
The Inner Solar System Exploring the Solar System Mercury, Venus, Mars Mercury and Venus too hot for life Mars Exploration Multiple missions Found evidence of water The Outer Solar System Jupiter, Saturn, Uranus, Neptune Layered structure No solid surface Jupiter Comet Shoemaker-Levy Galileo spacecraft Saturn Cassini spacecraft Moons and Rings Jupiter s Moons Io, Europa, Ganymede, Callisto and about 60 others Saturn s Moons Titan, Mimas, Hyperion and about 60 others Rings Ice and rock - more ice in Saturn s rings Pluto Pluto Outermost planet.3% of earth s mass Three moons Charon, Nix, Hydra Formation Captured comet or asteroid What about density? Still open to question Asteroids, Comets, and Meteors Asteroids Small rocky bodies Orbit sun Most in belt between Mars and Jupiter Comets Dirty snowballs Orbit outside Pluto Oortcloud Kuiperbelt Halley s Comet Stardust and Deep Impact missions Meteoroids, Meteors, and Meteorites Meteor showers Original solar system material
Planetary Summary Mercury Venus Earth Mars Jupiter Saturn Planet Mass (Earth=1) 0.06 0.82 1.00 0.11 318 95 Density (g/cm 3 ) 5.4 5.2 5.5 3.9 1.3 0.7 Major Constituents Rock, Iron Rock, Iron Rock, Iron Rock, Iron H, He H, He Mercury, Venus, Earth, and Mars are called: A galaxial objects B standard planetoids C Jovian planets D terrestrial planets Uranus Neptune 14 17 1.3 1.7 Ices, H, He Ices, H, He Jupiter, Saturn, Uranus, and Neptune are called: A galaxial objects B standard planetoids C Jovian planets D terrestrial planets The asteroid belt is located: A between the Sun and Mercury B between Mercury and Venus C between Mars and Jupiter D outside of our solar system Distinctive features of the solar system such as the rotation of the Sun, orbits of the planets, and the distribution of mass into one large central object and lots of much smaller orbiting bodies is explained by: A the Hubble theory B the nebular hypothesis C the Trefil and Hazen gambit D the relativity theory What are the Jovian planets composed of? A hydrogen and helium B rocky substances C element 119 (Jo) D iron (Fe)
Scientists estimated that the mass of the Earth has grown by about what mass each day? A 20 kg B 20,000 kg C 2 million kg D it is not growing at all Which elements is the mantle rich in? A H, O and C B P, S, Mn and Cl C O, Si, Mg and Fe D transuranic elements such as Np and Pu Outgassing and gravitation escape are processes by which: A planets form an atmosphere B space travel may become possible C solar systems form planets D string theory can be applied Have you ever seen a meteor or meteorite? A yes B no C don t know what these are Should future missions to the planets carry people or should they only carry machines? A yes B no