Geology

• Milky Way Galaxy

  -          a disc - shape spiral galaxy (barred spiral)

  -          has consumed other galaxies such as Sagittarius Dwarf Galaxy
• Scutum-Centaurus & Perseus – two spiral arms of the milky way
• Canis Major Dwarf Galaxy – closest galaxy to the Milky Way
• Orion-Cygnus Arm – where solar system is located
• Galactic/Cosmic Year – 250 million years to complete one rotation around Milky Way
• “Our position in the Milky Way Galaxy: in one of the arms of the spiral”
• Plutoids

  -          are celestial bodies in orbit around the sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighborhood around their orbit.”

  -          small round things beyond Neptune that orbit the sun and have lots of rocky neighbors. Ex. Pluto and Eris.
• Hydrosphere (makes it a blue planet): contains all of the earth’s solid, liquid, and gaseous water.
• Atmosphere (swirling clouds): contains all of the earth’s air
• Geosphere or Lithosphere: contains all of the cold, hard, solid rock of the planet’s crust.
• Biosphere: contains all of the planet’s living organisms
• The Earth is spherical and oblate because of some evidences like shadow during eclipse, disappearing ships at sea, TV wave transmission
• Eratosthenes

  -          he provides an estimation of the Earth’s size (276 – 195 BC)

  -          assumptions: parallel sun’s rays

  -          spherical shape

  radius = arc length/angle
• Atmosphere’s composition

  -          Nitrogen: 78%

  -          Oxygen: 21%

  -          Other elements
• Atmospheric Circulation

  -          Low latitudes: insolation highest

  -          Warm humid air as clouds in equatorial region

  -          North and south border: cloud-free where air descends

  -          Higher Latitudes: cyclonic systems where warm air interacts with cold air
• Hydrosphere

  -          Total mass of water on earth’s surface: 98% in oceans and 2% in streams, lakes, ground water, glaciers

  -          Covers 71% of earth’s surface

  -          Influence on weather and climate: cold vs warm ocean currents and major source of water for hydrologic cycle
• Geosphere

  -          Mountain Chains (Andes, Alps, Himalayas, North American Cordillera, etc.)

  -          Island Arcs (Philippines, Indonesia, Japan, Marianas, etc.)

  -          Submarine landscape: oceanic ridges, abyssal plains, intraplate volcanoes/guyots (submerged flat-topped volcanoes), transform fault, trench
• Biosphere

  -          Part of the earth where life exists

  -          Set of all life forms

  -          Main factors for distribution: P, T, chemistry
• Systems

  -          provides framework for understanding how each part of the Earth works and why it is changing

  -          a system is a group of interdependent materials that interact to form a united whole and are influenced by related forces.

  -          Materials in a system change in an effort to reach and maintain equilibrium
• Types of Earth Systems

  -          Closed: exchanges only energy with its surroundings (Ex. Earth)

  -          Open: exchanges both heat and matter with surroundings; applies to most earth systems (Ex. River systems, volcanic systems, etc.)
• Equilibrium – a condition in which the net result of the forces acting on a system is zero
• Fundamental Law: Any system tends to run down: to lose energy to the surroundings.
• For spontaneous change to occur, the total energy of a system must decrease. The most stable state is the one with the lowest energy
• Earth Systems

  -          earth is an interacting system of matter and energy, that as part of its functioning produces phenomena like volcanoes, glaciers, mountain ranges, oceans, and continents

  -          the energy that keeps this system going is on one hand the internal heat (from radioactive decay) that drives plate tectonics, and on the other hand solar energy that maintains ocean and atmosphere circulation and helps to drive erosion
• Gaia Hypothesis

  -          proposed by James Lovelock and Lynn Margulis

  -          The biosphere is a self-regulating system that controls its physical and chemical environments
• -          Negative feedback: attainment of equilibrium involves a response that opposes the change; mitigates the impacts of the process.

  -          Example of a negative feedback: solar radiation = global warming that also leads to more white daisies = reflect radiation, lower surface

  -          Positive feedback – the reaction invokes a response that amplifies the change; enhances the impacts of the process
• Major Earth Systems

  -          Hydrologic System

  -          Tectonic System
• Hydrologic System

  -          A complex cycle through which water moves from the oceans, to the atmosphere, over the land, and back to the oceans again.

  -          Water in this system is moving as surface runoff, groundwater, glaciers, ocean waves and current-erodes, transports, and deposits surface rock materials
• Hydrologic Cyle

  -          Precipitation = Runoff + Evapotranspiration + Infiltration (P = R + ET + I)
• Tectonic System

  -          Involves the movement of the lithosphere which broken into a mosaic of separate plates which move independently, separating, colliding, and sliding past one another.

  -          the margins of the plates are sites of considerable geologic activity such as seafloor spreading, continental rifting, mountain building, volcanism, and earthquakes.
• Systems interact! Biosphere, atmosphere, hydrosphere, geosphere interact with each other
• Cosmology

  -          the scientific study of the large-scale properties of the Universe as a whole

  -          uses the scientific method to understand the origin, evolution and ultimate fate of the entire Universe

  -          involves the formation of theories or hypotheses about the universe which make specific predictions for phenomena that can be tested with observations
• Big Bang Cosmology

  -          a broadly accepted theory for the origin and evolution of our universe

  -          postulates that 12 to 14 billion years ago, the portion of the universe we can see today was only a few millimeters across

  -          it expanded from this hot dense state into the vast and much cooler cosmos we currently inhabit

  -          remnants of this hot dense matter still pervade the universe and is visible to microwave detectors as a uniform glow across the entire sky
• 2 Pillars of the Big Bang Model

  -          General Theory of Relativity (Einstein, 1916): A modification of Newton’s Theory of Gravitation and it explains peculiarities of Mercury’s orbit and bending of light by the Sun

  -          Cosmological Principle: Assumes that matter in universe is uniform and isotropic when averaged over large scales
• Big Bang model is supported by 3 important observations: The Expanding Universe, Abundance of light elements (H, He, Li), and Uniform cosmic microwave background radiation (CMB)
• The Expanding Universe - Edwin Hubble's 1929 observation that galaxies were generally receding from us provided the first clue that the Big Bang theory might be right
• Abundance of light elements, H, He, Li - The Big Bang theory predicts that these light elements should have been fused from protons and neutrons in the first few minutes after the Big Bang.
• Uniform cosmic microwave background radiation (CMB) - The early universe should have been very hot. The cosmic microwave background radiation is the remnant heat leftover from the Big Bang
• Big Bang Misconceptions

  -          Big Bang did not occur at a single point in space as an "explosion."

  -          Better: As the simultaneous appearance of space everywhere in the universe. That region of space that is within our present horizon was indeed no bigger than a point in the past.

  -          here is no "center of expansion" - a point from which the universe is expanding away from.

  -          By definition, the universe encompasses all of space and time as we know it, so it is beyond the realm of the Big Bang model to postulate what the universe is expanding into.
• ET Hazards – such as galactic collisions and black holes