SOLAR SYSTEM GENESIS & EARTH

• WHERE THE HECK ARE WE?
• Our solar system located in a spiral galaxy called the Milky Way. Completes one rotation every 240 million years.
• Our star is located about 26,000 light years (the distance a photon of light can travel in one year's time [186,000 mi/sec] = 5,865,696 x 106 miles) from the galaxy edge.
• ALCHEMY LIVES!!
• Hydrogen (70%) is fused into Helium (27%)
• Heavier elements existing as gases in the center (Temp > 20 million ^oC).
• Sun converts 596 million mt of H into 532 million mt He each second!!
• ALCHEMY @ HIGHER T & P
• Capable of producing all known elements using the "Lego-block" model of chemistry
• Nuclear fusion at:
• 1-200 million ^oK; pressure > 1000 gm/cm³ then Helium is transformed to Carbon, Oxygen, Neon
• 2-5 billion ^oK results in the formation of Nickel & Iron
• 18^th CENTURY INSIGHT
• Theory must account for basic Newtonian fact that there is a physical order.
• Titius-Bode (1772) recognized mathematical order to the solar system.
• A rough rule that predicts the spacing of the planets in the Solar System as a mathematical expression.
• The law relates the mean distances of the planets from the sun to a simple mathematic progression of numbers.
• The Philosopher's Angle
• Kant (1775) - Laplace (1815) Nebular Theory
• Gravitational instability, Accretion & Condensation
• PROBLEM with Angular Momentum
• Leclercq's Catastrophic Theory
• Meteorite impact of the sun resulted in:
• Distribution of chemical elements into space
• Underwent condensation
• Planet formation.
• Problems
• Successful Nebular Theory
• Nebular formation
• Material ejected from supernovas; distinct elemental composition homogenized during rotation
• Distribution of planetary bodies
• Condensation of heated elements after incandescence
• Composition of terrestrial and jovian planets.
• Successful Nebular Hypothesis II
• Protoplanet evolution via accretion
• Dissipation of gases
• Solar wind drove lighter elements outward
• Angular momentum
• Ionized gases interacting with sun's magnetic field and/or convection currents
• Cold Accretion Model
• Planet originally unsorted mass (homogenous) of metals and silicates
• Differentiation due to internal heating.
• Partial melting due to
• Accretionary heat,
• Depth-temperature relationship
• Heat generated via radioactive decay
• Lighter elements (silicates) rise to crust
• Hot Accretion Model
• Planetary materials accreted hot (> 1000 ^oC).
• Heterogenous materials differentiated during accretion
• Hotter elements crystallizing first forming the core,
• Silicates forming later forming the crust.
• Early Atmospheric Development
• Accretionary matter contained volatiles.
• Hydrogen, nitrogen, and carbon; some contain water.
• Outgassing resulted in early atmosphere (1st marine sediments at 3,800 MY BP).
• Evidence Supporting Oxygenless Atmosphere
• Near Absence of Carbonate Rocks (CaCO₃)
• Carbonic acid prevents carbonate rock formation
• Absence of Hematite (oxidized Iron)
• Abundant Pyrite
• Unoxidized Carbon (dark-colored rocks)
• Unoxidized Uraninite
• Banded Iron Formations (BIF's Fe₂O₃)

GE142