Transcript Our solar system is believed to have originated in one such cloud

Big Circumstance:
Earth’s early history and why our planet is unique
How It All Began
…Or At Least How We Think It Began
…O.k. it’s a good guess
Universe Originated as a Singularity
The Big Bang splattered radiation in all directions
Expansion and cooling; atomic particles formed
through conversion of energy to mass.
E = mc2 (energy = mass x speed of light 2 )
Simple elements (hydrogen, then helium)
fused to form first stars
Heavier elements produced within giant pressure
cookers (stars)
Evidence for Big Bang
1. Background radiation
(excess radiation picked up by radio telescopes cannot be
accounted for if it is assumed that the universe is static).
2. Red shift in light spectrum galaxies
Light of an object moving toward an observer is shifted to
blue (shorter wavelength, higher frequency)
Light from an object moving away from observer is shifted
to red (longer wavelength, lower frequency)
High frequency,
Short wavelength
Low frequency,
Long wavelength
Light from galaxies tend to be shifted to red end of spectrum
An Analogy: Doppler Effect in Sound
Observer hears an increase in pitch when
the car approaches
(sound waves get scrunched together)
Analogous to blue shift in light
Observer hears an decrease in pitch as
the car moves away
(sound waves go further apart)
Analogous to red shift in light
If a galaxy is getting close to us, it should be blue shifted
If a galaxy is moving away from us, it should be red shifted
An Expanding Universe
The red shift observed in light of distant galaxies suggests that
the universe is expanding (everything is moving away from
everything else) and that this expansion must have resulted
from an incredible event, involving an incredible amount of
energy
Formation of Stars and Galaxies
Stars and galaxies
condensed out of
the matter
produced by the
Big Bang and
continued to move
away from the
initial singularity
(sort of a point of
explosion). This is
still occurring.
Redistribution of heavy elements
Elements heavier than hydrogen are produced within stars
Dispersion of heavy elements into space results from explosion
(supernova) of stars
Later stars are formed from the material of these exploded stars
Solar Nebula Hypothesis
Clumps of gas and dust accumulated,
forming large, irregular, nebulae “clouds.”
Our solar system is believed to have originated
in one such cloud.
Dust and gases settled gravitationally toward
mid-plane of slowly rotating disc.
After some of the matter had collected in centre
of disc, nuclear reactions began, forming the Sun
Remaining gas and dust, moving in circular
bands around Sun collided and accreted to
form planets.
Solar Nebula and Formation of Solar System
The Nine Eight Planets
Pluto
Neptune
Uranus
Saturn
Jovian
planets
Jupiter
Mars
Earth
Venus
Mercury
terrestrial
planets
Early Evolution of Earth
Heating, partial melting of Earth due to:
Impacting of extraterrestrial objects (meteorites)
Radioactive decay of unstable elements
Gravitational migration (sinking) of heavy elements
Evidence of Planetary Bombardment by Other Objects
Obliquity of Axis
Venus “overturned”
Uranus tipped on its side
All planets have at least some tilt
Jovian Planet Interior: Jupiter
Comparison of Atmospheric Components:
Jovian vs. Terrestrial Planets
Venus
Jupiter
Major:
Minor:
Hydrogen (81 %)
Helium (18 %)
Methane and other hydrocarbons
Ammonia
Phosphorus
Water Vapour
Major:
Minor:
Carbon Dioxide (96.5 %)
Nitrogen (3.5 %)
Sulphur Dioxide (0.015 %)
Water
Argon
Carbon Monoxide
Helium
Oxygen
Comparison of Atmospheric Components:
Venus vs. Earth
Venus
Major:
Minor:
Earth
Carbon Dioxide (96.5 %) Major:
Nitrogen (3.5 %)
Sulphur Dioxide (0.015 %)
Water
Minor:
Argon
Carbon Monoxide
Helium
Oxygen
Nitrogen (78 %)
Oxygen (21 %)
Argon (0.9 %)
Water Vapour (0.05 to 2 %)
Carbon Dioxide (0.03 %)
Methane,
Ozone
Rare Inert Gases
Evolution of Earth’s Atmosphere
1. Initial atmosphere much like Jupiter
(rich in Hydrogen and Helium derived from solar nebula)
- burned off by Solar Wind
2. Second atmosphere much like Venus
(dominated by Carbon Dioxide from Earth’s interior)
- “The Big Burp”
3. Third and present atmosphere
(rich in Oxygen)
- modified from second atmosphere due to
rise of anaerobic organisms
Important Implications:
Earth’s overall composition reflects that of the original “stuff”
of the Solar System but has been modified through time
due to:
1. Earth’s position relative to the Sun
2. Size of the Earth
3. Dynamic internal processes of Earth and resulting processes at the
surface (e.g. movement of tectonic plates)
4. Biological processes (e.g. photosynthesis)
Earth is rather unique in its composition – the diversity and
distribution of gaseous, liquid and solid components have
important implications to the influence of Earth materials on
human health and the use of Earth materials in forensic
studies
Also Remember: Earth As A Closed System
Material cycles within the system with no overall loss or gain
(note implications for global environmental change)
And: The Earth’s Four Spheres
Interchange of matter
among all subcomponents
of the Earth system
Note:
Humans are part of the
biosphere and are affected
by, and connected to:
the geosphere
the hydrosphere
the atmosphere
END OF LECTURE