THE PRIMORDIAL EARTH Hadean and Archean Eons

THE PRIMORDIAL EARTHHadean and Archean Eons

Solar System

Includes:

SunPlanetsMoonsAsteroidsComets


Terrestrial or Inner Planets

Mercury



Venus



Earth

Small Dense (4 - 5.5 g/cm3) Rocky and include Metals

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 densestMantle surrounds core. Surface temperature ranges

between roughly -50 and +60 °C.




Mars


Asteroid Belt

Between Mars and Jupiter

Likely a broken up planet orplanetesimal


Jovian or Outer Planets

Jupiter

Large Low density (0.7 - 1.5 g/cm3) Gaseous


Outer Planets

Saturn


Outer Planets

Uranus


Outer Planets

Neptune


Outer Planets

Pluto



Sun

The Sun is a star

Composition70% hydrogen 27% helium3% heavier elements

Temperature>20,000,000 ºC at interior

Energy comes from fusion of Hydrogen to form Helium


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


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)

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 EARTHHadean and Archean EonsOrigin 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 EARTHHadean and Archean EonOrigin 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 EARTHHadean and Archean EonOrigin of the Moon

THE PRIMORDIAL EARTHHadean and Archean EonsOrigin of the Universe

Big Bang TheoryEvidence: 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.)


Red shift:Light is shifted toward the red (or long wavelength) end of the spectrum.

Colors of the spectrum

R O Y G B I V 1. Red 2. Orange 3. Yellow 4. Green 5. Blue 6. Indigo

7. Violet



Red = long wavelengthsBlue = short wavelengths Microwaves and radio waves are longer than visible Ultraviolet and X-rays are shorter than visible.


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).


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.


Away from you

Towards you

At rest


Big Bang TheoryEvidence: 2. Observed temperature of the universe today

(background microwave radiation) 3 degrees above absolute zero


Big Bang TheoryEvidence: 3. Present abundances

of hydrogen and helium.


THE PRIMORDIAL EARTHHadean and Archean EonsFormation of the Solar System

The Solar Nebula Hypothesis

Documents

THE PRIMORDIAL EARTH Hadean and Archean Eons