Earth Science

• Non-scientific Beliefs about the origin of the universe

  • Narrative From Genesis
  • Rigveda
  • Greek Philosophers
  • Isaac Newton
  • Albert Einstein
  • Rene Descartes
• Genesis


  Describes how God separated light from darkness, and created the sky, land, sun, moon, stars, and every creature in a span of six days. "seven Days creation"
• Rigveda


  Hindu text describing an oscillating universe in which a "cosmic egg" or brahmanda contains the whole universe; sun, moon, planets, and space expanded out of a single concentrated point called "indu", and will eventually collapse again
• Greek Philosophers


  • Anaxagoras - believed in "primordial universe" (soup), proposed that the universe was made up of a substance that could be divided infinitely
  • Leucippus and Democritus - believed in an "Atomic Universe", universe was composed of very small, indivisible, and indestructible atoms
  • Aristotle and Ptolemy - believed in a "geocentric universe", Earth stays motionless while everything revolves around it
  • Nicolaus Copernicus - proposed "sun-centered solar system", motions of celestial objects without putting earth in the center of the universe called "Theory of Heliocentrism"
• Scientists


  • Isaac Newton - believed in a static, steady rate, infinite universe, with matter uniformly distributed and gravitationally balanced but essentially unstable
  • Rene Descartes - believed the universe was filled with elements of different sizes which shifted around each other, with the sun at the center made up of the smallest kind of element
  • Albert Einstein - first suggested the universe had a beginning, and that it ought to be expanding according to the general theory of relativity
• Big Bang Theory


  Most accepted scientific description of the evolution of the universe, 13.7 billion years ago the universe began as a small, extremely hot and dense "fireball" of energy that has been expanding ever since
• Steady State Theory


  Universe is constantly expanding but with fixed average density, with matter constantly being created to form new galaxies and stars as old ones are destroyed
• Oscillating Theory


  Universe undergoes periods of expansion and contraction, with all matter in the universe getting hotter and brighter then eventually collapsing together in a "big crunch", then a new "big bang" occurring to start a new universe
• The solar system formed due to a near collision between a passing rogue star and the sun about 5 billion years ago, according to the Encounter Hypothesis
• Nebular Hypothesis


  The solar system started from a spinning cloud of dust made of light elements, called a nebula, which slowly lost heat and increased in speed, leading to the formation of a flat rotating proto-planetary disk
• Protoplanet Hypothesis


  Sun and planets were created by the combination of matter from a whirling cloud of gas, with smaller particles accumulating and being taken in by the sun's gravity
• The Eight Planets


  • Mercury, Venus, Earth, Mars (terrestrial planets)
  • Jupiter, Saturn, Uranus, Neptune (Jovian/Jupiter-like planets)
• Mercury


  • Smallest terrestrial planet, mostly made up of a rocky crust, very difficult to see because it's so close to the sun
• Venus


  • Earth's sister planet, the Earth and Venus are very close to each other when orbiting the sun, and both relatively young
• Earth


  • Only planet known where life exists, made up of 2/3 water, largest terrestrial planet and fifth largest in the solar system, believed to be about 4-5 billion years old
• Mars


  • Reddish color, can be seen in the night sky, named after the Roman god of war
• Jupiter


  • Largest planet, 11 times bigger than the Earth in diameter, has a "Great Red Spot" which is a raging storm
• Saturn


  • Second largest planet, farthest planet that can be seen without a telescope, mostly made up of hydrogen and helium
• Uranus


  • Only planet that spins on its side, takes 84 years to complete an orbit from the sun, each night and day lasts 42 years
• Neptune


  • Named after the Roman god of the sea, bright blue because of methane gas clouds, most distant from the sun and takes 165 years to complete an orbit
• Layers of the Earth's Atmosphere

  • Troposphere - where weather occurs, temperature decreases with height
  • Stratosphere - where ozone layer is, temperature increases with height
  • Mesosphere - coldest layer, protects from meteors
  • Thermosphere - hottest layer due to absorption of solar energy, auroras occur here
  • Exosphere - final layer, stretches into space, provides protection from meteoroids and space debris
• Earth's Subsystems


  • Atmosphere - gaseous blanket of air
  • Biosphere - all living organisms
  • Geosphere - physical earth, rock, magma, soil
  • Hydrosphere - all water on Earth
  • Lithosphere - solid land and semi-solid land underneath
• Layers of the Earth

  • Core - innermost layer, primarily iron and nickel
  • Mantle - solid rock matter and molten rock
  • Crust - Earth's solid exterior, oceanic and continental
• Mineral


  Naturally occurring, inorganic, solid substance with a definite chemical composition and ordered crystalline structure
• Physical Properties of Minerals

  • Luster - appearance of reflected light
  • Hardness - strength of chemical bonds
  • Streak - color in powdered form
  • Color
  • Crystal Habit - tendency to form characteristic shapes
  • Crystal Form - solid crystalline object with flat faces
  • Cleavage - tendency to break along planes of weakness
  • Fracture - tendency to break irregularly
  • Specific Gravity - density
• Chemical Properties of Minerals

  • Reaction to acids
  • Magnetism
  • Radioactivity
• The Rock Cycle


  • Igneous Rocks - formed from solidification of molten materials
  • Sedimentary Rocks - formed from weathering, erosion, deposition, compaction and cementation
  • Metamorphic Rocks - formed from igneous or sedimentary rocks exposed to high pressure and/or temperature
• Ore


  Naturally-occurring material from which minerals of economic value can be extracted
• Types of Mineral Resources

  • Metallic - ferrous and non-ferrous
  • Non-Metallic
• Types of Ore Deposits

  • Magmatic - concentrated within igneous rock
  • Hydrothermal - concentrated by hot aqueous fluids
  • Sedimentary - concentrated by chemical precipitation
  • Placer - concentrated by gravity separation
  • Residual - accumulated through chemical weathering