Transcript Slide 1
THE PRIMORDIAL EARTH Hadean and Archean Eons Solar System Includes: Sun Planets Moons Asteroids Comets THE PRIMORDIAL EARTH Hadean and Archean Eons Terrestrial or Inner Planets Mercury THE PRIMORDIAL EARTH Hadean and Archean Eons Terrestrial or Inner Planets Venus THE PRIMORDIAL EARTH Hadean and Archean Eons Terrestrial or Inner Planets Earth Small Dense (4 - 5.5 g/cm3) Rocky and include Metals THE PRIMORDIAL EARTH Hadean and Archean Eons Diameter ± 13,000 km (8000 mi) Oceans cover > 71% of surface Atmosphere: 78% nitrogen 21% oxygen Average density = 5.5 g/cm3 Crust density = 2.5 - 3.0 g/cm3 Core is densest Mantle surrounds core. Surface temperature ranges between roughly -50 and +60 °C. THE PRIMORDIAL EARTH Hadean and Archean Eons Terrestrial or Inner Planets Mars THE PRIMORDIAL EARTH Hadean and Archean Eons Asteroid Belt Between Mars and Jupiter Likely a broken up planet or planetesimal THE PRIMORDIAL EARTH Hadean and Archean Eons Jovian or Outer Planets Jupiter Large Low density (0.7 - 1.5 g/cm3) Gaseous THE PRIMORDIAL EARTH Hadean and Archean Eons Outer Planets Saturn THE PRIMORDIAL EARTH Hadean and Archean Eons Outer Planets Uranus THE PRIMORDIAL EARTH Hadean and Archean Eons Outer Planets Neptune THE PRIMORDIAL EARTH Hadean and Archean Eons Outer Planets Pluto THE PRIMORDIAL EARTH Hadean and Archean Eons THE PRIMORDIAL EARTH Hadean and Archean Eons Sun The Sun is a star Composition 70% hydrogen 27% helium 3% heavier elements Temperature >20,000,000 ºC at interior Energy comes from fusion of Hydrogen to form Helium THE PRIMORDIAL EARTH Hadean and Archean Eons Sun Sun's energy is the force behind many geologic processes on Earth: Evaporation of water to produce clouds which causes precipitation which causes erosion Uneven heating of the Earth's atmosphere causes winds and ocean currents Variations in heat from sun may trigger continental glaciations Sun and moon influence tides THE PRIMORDIAL EARTH Hadean and Archean Eons Moon The Moon is a satellite Diameter ± 1700 km Density ± 3.3 g/cm3 Rotates on its axis at same rate as it revolves around Earth, which results in same side of Moon always facing Earth. Far side of moon is more densely cratered Dominant rock type is anorthosite (related to gabbro) THE PRIMORDIAL EARTH Hadean and Archean Eons Geology of the Moon Lunar highlands Light-colored Rough topography Highly cratered More than 4.2 billion years old (Hadean in age) Maria (once thought to be seas) Singular = Mare, plural= Maria Large, dark areas Covered with basaltic lava flows Age of basalt is 3.8 to 3.2 billion years THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Moon Moon may have formed as a result of an impact of another body with Earth about 4.4 billion years ago. Debris from the impact thrown into orbit around Earth and aggregated to form the Moon. THE PRIMORDIAL EARTH Hadean and Archean Eon Origin of the Moon Heat from impacts led to melting and differentiation (or segregation of materials of different density; low density materials rose and high density materials sank). 1. Low density alumino-silicates rose to surface to form a crust 2. Higher density iron-rich minerals sank to form the lunar mantle, and possibly a small core 3. Basaltic lava flows of the maria erupted following large impacts somewhat later. THE PRIMORDIAL EARTH Hadean and Archean Eon Origin of the Moon THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Big Bang Theory Evidence: 1. The galaxies are rapidly moving apart (Hubble's Law); indicates that galaxies were closer together in the past (This was discovered in 1929 by Edwin P. Hubble; In 1914, W.M. Slipher first noted the red shift.) THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Red shift: Light is shifted toward the red (or long wavelength) end of the spectrum. Colors of the spectrum ROY G BIV 1. 2. 3. 4. 5. 6. Red Orange Yellow Green Blue Indigo 7. Violet THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Red = long wavelengths Blue = short wavelengths Microwaves and radio waves are longer than visible Ultraviolet and X-rays are shorter than visible. THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe The spectrum of a star reveals: •The star's composition (by means of absorption lines; various elements in the star's atmosphere absorb parts of the light of the spectrum) and •Whether it is moving toward or away from the Earth (and at what speed). THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Light reaching us from distant receding galaxies has its absorption lines shifted toward the red end of the spectrum. This indicates that the galaxy is moving away from the Earth. So, the red shift indicates that the universe is expanding. A similar phenomen, except related to sound, is the Doppler Effect. At rest Away from you Towards you THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Big Bang Theory Evidence: 2. Observed temperature of the universe today (background microwave radiation) 3 degrees above absolute zero THE PRIMORDIAL EARTH Hadean and Archean Eons Origin of the Universe Big Bang Theory Evidence: 3. Present abundances of hydrogen and helium. THE PRIMORDIAL EARTH Hadean and Archean Eons Formation of the Solar System The Solar Nebula Hypothesis