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Earth and Other Planets
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 Formation of the Solar System
Clues to the Origin of the Solar System
• Solar system– Objects gravitationally bound to Sun
• Deduction of origin– Observations
• Earth• Space
The Solar System
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
Mass in the Solar System
The Planets and Their Characteristics
The Nebular Hypothesis
• Nebular Hypothesis– Cloud of dust and gas– 99% H and He
• Collapse of nebula– Planetary orbits– Clumping of matter– Planetesimals – Temperature
The Stages in Solar System Formation
The Inner Planets –Small and Rocky
Jupiter – Gas Giant Planet
The Science of Life
• Gravity and bones
The Formation of Earth
• Planetesimals– Combined to form earth
• Great bombardment– Meteors– Growth of planet
• 20 metric tons per day
Artists Impression of the Earth’s Great Bombardment
Disk around a Young Star
Differentiation
• Differentiation– Heat from collisions– Dense material sank to center– Lighter material rose to surface
• Structure– Core– Mantle– Crust
The Principal Layers of the Earth
Technology
• Producing world-record high pressures
The Formation of the Moon
• Big splash– Large object impacted earth– Parts of mantle blown into orbit– Moon formed from this material
Formation of the Earth’s Moon
Planetary Idiosyncrasies
• Cratering– Mercury, Mars, Moon– None on earth
• Weathering
• Rotation– Venus – Earth’s axis– Uranus
The Science of Life
• When could life begin?• Effect of collisions
The Evolution of Planetary Atmospheres
• Earth’s atmosphere– Early– Outgassing
• Atmosphere was N2, CO2, H2, and H2O
– Gravitational escape– Living organisms
Exploring the Solar System
The Inner Solar System
• Mercury, Venus, Mars– Mercury and Venus too hot for life
• Mars exploration– Multiple missions– Found evidence of water
Surface of Mars
The Phoenix Lander on Mars
Science of Life
• Why look for life on Mars?
• Source of science fiction
• Current views
The Outer Solar System
• Jupiter, Saturn, Uranus, Neptune– Layered structure– No solid surface
• Jupiter– Comet Shoemaker-Levy– Galileo spacecraft
• Saturn– Cassini spacecraft
Theoretical View of the Interior of Jupiter
Comet Shoemaker-Levy Impacted Jupiter in 1994
Saturn with Its Rings and Moons
Moons and Rings of the Outer Planets
• Moons– Io– Europa– Titan
• Rings– Ice and rock
Artist’s Conception of the Oceans of Europa
Pluto and the Kuiper Belt
• Pluto– .3% of Earth’s mass– Orbit tilted out of plane of other planets– Three moons– Formation
• Captured comet or asteroid• Still open to question
– Plutoid designation in 2008
Pluto and Its Moon, Charon
Science in the Making
• The discovery of Pluto• Xena
– Orbits sun every 560 years– One moon– Larger than Pluto
Science in the Making
• The Voyager Satellites• Discoveries
Asteroids
• Asteroids– Small rocky bodies– Orbit sun– Most in belt between Mars and Jupiter
Comets
• Comets– Dirty snowballs
• Orbit outside Pluto• Oort cloud• Kuiper belt
– Halley’s Comet– Stardust and Deep Impact missions
Comet’s Tail
Meteors
• Meteoroids, meteors, and meteorites– Meteor showers– Original solar system material
Major Meteor Showers
Science in the Making
• Discovering new planetary systems• Use the Doppler effect• Search for transits
Changes in Redshift or Blueshift of Light
Planet in Front of a Star
Kepler Satellite