ORIGINS

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ORIGINS

• Oceans Continents
• Crust
• Earth
• Solar System
• Universe

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The Universe

• Planets
• Stars
• Galaxies
• Clouds of Dust Gas
• Interstellar Space

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Clouds of dust and gas in Eagle Nebula (Hubble
Picture)
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View of Galaxies in deep space from Hubble space
telescope
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Sombrero Galaxy
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Andromeda Galaxy
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Milky Way Galaxy
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Scientific Method

• Observations or experiments
• Hypotheses
• Testing
• Theories (Scientific Truths)

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Origin of Universe

• Evidence
• All galaxies in universe appear to be moving away
  from one another (Red Shift in Starlight)
• The greater their distance the faster they are
  receding
• The temperature of interstellar space is not 0o K
  but 2.7o K
• Big Bang Theory

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Origin of Solar System

• Evidence
• Astronomical observations of stars beyond solar
  system
• Observations of structure
• composition of solar system
• Internal structure and composition of Earth

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Star Formation in a Dust and Gas Cloud in Scorpius
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Sun during eclipse
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Solar Spectrum
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The Sun

• Sun makes up 99.9 of Solar System
• Sun is mainly made of
• Hydrogen (element 1, simplest and most abundant
  element in universe)
• Helium (element 2, second most abundant)
• Solar energy produced by nuclear fusion
• 4 Hydrogen nuclei 2 Helium nuclei energy

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The Solar System

• With exception of Pluto, all planets occupy
  sub-circular orbits
• All orbit in the same plane (ecliptic) and in
  same direction
• Nearly all rotate in same direction about axes
  that are nearly perpendicular to ecliptic

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The Planets

• Inner Planets
• Mercury, Venus, Earth, Mars
• Small, dense, rocky.
• Few moons

• Outer Planets
• Jupiter, Saturn, Uranus, Neptune
• Large, low density, icy.
• Many moons
• Pluto

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Solar System and Outer Planets
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Internal structure of Earth

• Atmosphere lt1 g/cm3
• Hydrosphere 1 g/cm3
• Crust 2.7-2.9 g/cm3
• Mantle 3.3-5.6 g/cm3
• Core 10-14 g/cm3
• A Differentiated Planet

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Nebular Theory

• Star systems are formed by the gravitational
  collapse of diffuse clouds of dust and gas
  (nebulae)
• Cold clouds of dust and gas (mainly hydrogen) are
  most abundant constituents of universe
• Gravitational collapse always leads to rising
  temperatures.

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Planet Earth

• Rising temperatures lead to partial melting
• Light melting fractions rise
• Heavy melting fractions sink
• Result - a layered structure with core, mantle,
  crust, ocean and atmosphere

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Crust Two Types

• BASALTIC CRUST 2.9 g/cm3
• (3-5mls thick)
• Iron, magnesium, silica rock (mafic rock)
• GRANITIC CRUST 2.7 g/cm3
• (10-40mls thick)
• Aluminum, silica rock (felsic rock)
• Crust rigid and brittle generates earthquakes

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Isostacy

• The floating balance that exists between dense
  plastic mantle and light brittle crust

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Elevation of Earths Surface

• Composition
• Density
• Temperature

Thickness
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