Earth and Other Planets 3 November 2015 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.

Chapter Outline The Formation of the Solar System Exploring the Solar System The Earth

The Formation of the Solar System

Clues to the Origin of the 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 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 distance2 Flux emitted = constant x T4 [Stefan-Boltzmann] Concluding from above yields T = constant / distance0.5

Nebular Condensation Chemistry

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

iClicker Question 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

iClicker Question 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

iClicker Question 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 Great bombardment Combined (accretion) to form earth Great bombardment Meteors Growth of planet 20 metric tons per day

Differentiation Differentiation Structure 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

iClicker Question Which of the diagram represents the mantle of the Earth? A B C D E None of the above.

iClicker Question Which of the diagram represents the outer core of the Earth? A B C D E None of the above.

iClicker Question 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.

iClicker Question 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 N2, CO2, H2, & H2O Gravitational escape Living organisms

iClicker Question All our observations of the Sun and planets have been made from the surface of the Earth. A True B False

iClicker Question All planets and most of their moons orbit in the same direction around the Sun A True B False

iClicker Question Almost all planets and moons rotate on their axes in the same direction as the planets orbit the Sun. A True B False

iClicker Question What is the shape of our solar system? A spherical (like a ball) B flat (like a dish) C tubular (like a hot dog)

iClicker Question The mass in our solar system is evenly distributed. A True B False

Exploring the Solar System

The Inner Solar System Mercury, Venus, Mars Mars Exploration Mercury and Venus too hot for life Mars Exploration Multiple missions Found evidence of water

The Outer Solar System Jupiter, Saturn, Uranus, Neptune Jupiter Saturn Layered structure No solid surface Jupiter Comet Shoemaker-Levy 9 Galileo spacecraft Saturn Cassini spacecraft

The Outer Solar System II

Moons and Rings Jupiter’s Moons Saturn’s Moons Rings Io, Europa, Ganymede, Callisto and 63 others known Saturn’s Moons Titan, Mimas, Hyperion and about 59 (61?) others Rings Ice and rock - more ice in Saturn’s rings Moons and Rings

Dwarf Planet Pluto Surprises It has moons Original moon discovered 1978 Charon (KAIR’ en) Now more 2005 discovery of 2 additional moons Named Nix and Hydra 2011 #4 is P4 (Kerberos) July 7, 2012 #5 is P5 (Styx)

Pluto’s Interior to Surface Old -> New Model partially hydrated rock core water ice layer II predominant water ice layer I Model 2 organics layer predominantly water ice layer

The Launch of New Horizons Pluto Mission 17 Jan 2006 http://www.youtube.com/watch?v=KNJNaIoa5Hk

Io’s Volcanoes from New Horizons

Pluto

Pluto’s Methane (frozen)

Charon

Pluto

Pluto Atmosphere Detection

Pluto and Charon

Carbon Monoxide (Frozen)

Solar Wind at Pluto

Pluto “Heart” Region

Pluto Mountain Range

Nix and Hydra

Pluto, True Color

Asteroids, Comets, and Meteors Small rocky bodies Orbit sun Most in belt between Mars and Jupiter Comets Dirty snowballs Orbit outside Pluto Oort cloud Kuiper belt Halley’s Comet Stardust and Deep Impact missions Meteoroids, Meteors, and Meteorites Meteor showers Original solar system material

Planetary Summary

iClicker Question Mercury, Venus, Earth, and Mars are called: A galaxial objects B standard planetoids C Jovian planets D terrestrial planets E dwarf planets

iClicker Question Jupiter, Saturn, Uranus, and Neptune are called: A galactic objects B standard planetoids C Jovian planets D terrestrial planets E dwarf planets

iClicker Question 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

iClicker Question 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

iClicker Question What are the Jovian planets primarily composed of? A rocky substances B element 119 (Jo) C hydrogen and helium D iron (Fe) E silicon (Si)

iClicker Question Outgassing and gravitational 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

iClicker Poll Question Have you ever seen a meteor or meteorite? A yes B no C don’t know what these are

iClicker Poll Question Should future missions to the planets carry people or robots? A People only B Robots only C People and robots D Neither, missions to planets are a waste of money