Transcript Oceanography Chapter 1 – “Origins”

Bell Work
9/8/2011
Chapter 2 in the Oceanography textbook is
entitled “Origins”. What might we be
studying the “origins” of in this chapter?
Oceans
Solar System
Earth
Moon
Universe
Atmosphere
Origins – Oceanography
Chapter 2
Part 1: Origin of Universe & Galaxies
Big Bang Theory
• Event that occurred approximately 14 billion years ago.
• All mass & energy was concentrated at a geometric point.
• The Big Bang marks the beginning of space and time.
Evidence Supporting the Big Bang
Theory
1.
2.
3.
4.
Expansion of the universe.
Cosmic Background Radiation.
Nucleosynthesis of light elements.
Formation of galaxies.
ELECTRO-MAGNETIC
SPECTRUM
Smallest wavelength
Largest wavelength
What we see with our eyes
Looking at the Crab Nebula with
the EM Spectrum
UV
MW
IR
RADIO
X-RAY
VISIBLE
Expansion of Universe
Red Shifted = moving away
Blue Shifted = moving
towards
90% of all stars & galaxies
observed are moving away from
the Milky Way
Cosmic Background Radiation
• Ancient universe had small variations in
temperature.
• Over 14 billion years, gravity magnified these
small differences into clusters of galaxies
today.
A sky map of cosmic
background radiation
(microwave) taken by
NASA’s satellite called
COBE.
Scale & Structure in Universe
Universe is composed of voids and galaxy clusters. Voids
could be millions of light years across.
Nucleosynthesis of Light Elements
• Hydrogen atoms:
– the most common form of
matter in the universe.
• Atoms have mass. Clump
together under gravity.
• Formation of elements:
– He through Fe (iron) inside
stars (nuclear fusion)
– Heavier elements in supernova explosion (Fe &
beyond)
Formation of Large-Scale Structures
Galaxies, like our Milky Way, are
composed of stars, dust, gas and
debris held together by gravity.
Galaxies
The Milky Way is approx. 100,000 light years in diameter.
Our solar system is located on an outer spiral arm 27,000
light years from the galactic bulge. A black hole may be
found within the bulge of the galaxy.
Types of Galaxies
Irregular Galaxy
Spiral Galaxy
Elliptical Galaxy (globular
cluster)
More Types of Galaxies
Part 2: Origin Stars (Life Cycle of a
Star)
Life Cycle of a Star
Life Cycle of a Star
Step 1: All stars are born in nebulae.
• Nebulae are clouds
of dust & gas within
galaxies.
• Nebulae are
concentrated in the
arms of spiral
galaxies.
Types of Nebulae
Supernova Nebula
Dark Nebula
Proto-stars
• Proto-stars grow as
hydrogen & helium gas
are pulled together by
gravity.
• Proto-stars are not hot
enough for fusion to
occur.
Artists rendition of a
protostar
As material continues to collect,
the protostar gets hotter and hotter
and hotter until . . . . . .
Gamma & Xrays
Nuclear fusion begins and blows off the
remaining gas (our first atmosphere)!
Stage 2: Main Sequence Star
Our sun is a main sequence star (stable).
It is a yellow dwarf star. Nuclear fusion of
hydrogen gas into helium gas powers our
Sun.
Equation of Fusion
e = mc2
4 H + 2e-
1 He + 2  + photons
This is the nuclear reaction that happens inside stars
and gives off massive radiation. All elements up to
iron form inside stars, the remaining elements form
during a supernova explosion.
Bell Work
9-11-12
What event in a star’s life cycle changes a
proto-star into a main sequence star?
Nuclear Fusion occurs when the
core temperature = 10 million
degrees Kelvin
Stage 3: Red Giant Stage
• Hydrogen in the
core is used up
and fusion no
longer balances
gravity.
• Star expands and
collapses.
• Gravity wins!
Red Giant Stage - Unstable
Stage 4 – Nova Stage
Stage 5: White Dwarf Stage
• All fuel is used up.
• Dim, faint with high
temperature.
• Some Sun-like stars
become white dwarfs
made of carbon.
• Some white-dwarfs
flare up to a nova.
Bell Work
9-12-12
Where do the following elements form?
Hydrogen . . . Big Bang
Helium to iron . . . Inside stars
Elements heavier than iron . . .
Supernova explosion
Types of Stars
Cool &
Bright
Hot &
Bright
Dying stars
Our sun
Dead stars
Hot &
Dim
Cool &
Dim
HR Diagram
Bell Work
9-13-12
Besides having life and abundant liquid
water, what makes Earth different from
the other terrestrial planets?
Large moon
Magnetic field
High Density
Plate Tectonics (volcanoes)
Part 3: Origin of the Solar System
Condensation Theory
•The condensation theory
explains how stars &
planets are believed to be
formed.
•Condensation theory is
based on the observation
of stars and planets at
different stages of
development.
•Scientists have inferred a
sequence in which these
stages occur.
Origin of Our Solar System
Metals (Fe, Mg,
Al, Mn) & Rock
(Si, K, Ca) – high
melting points
Gases like methane
(CH4) and ammonia
and solids like ice –
low melting points
5 billion years
ago:
A solar nebula +
shock wave &
heavy atoms from
a supernova=
formation of solar
system.
Formation of Planets
Terrestrial
planets
Planet formation
Gas planets
•New planets formed by a
process called accretion,
the clumping of small
particles into large masses.
•Accretion lasted about 30
to 50 million years.
•As the sun began nuclear
fusion, solar radiation
swept past the inner
planets clearing excess
particles and stopping the
accretion process.
Our Solar System
• Eight planets, asteroid
belt, and icy bodies
revolve around a star
(our sun) in a plane.
• Planet composition:
– Inner 4 planets are
terrestrial (rock/metal)
– Outer 4 are gas giants
(gas/ice)
• Beyond Neptune are icy
bodies (including Pluto)
and asteroids.
Terrestrial Planets
Terrestrial planets are
small, dense, and
composed of rock.
Venus is the hottest planet in
the solar system due to runaway greenhouse effect.
Mercury is a small,
hot planet made
mostly of iron.
More Terrestrial Planets
Mars is a dead planet with
little atmosphere & evidence
of liquid water on it’s surface.
Terrestrial
planets have few
or no moons and
no rings.
Gas Planets
Gas Planets are large, with low
density, and composed of methane
& ammonia gas.
More Gas Planets
Uranus & Neptune get their
blue color from methane gas.
Gas planets have lots of moons, rings, and no
craters.
Moons of Gas Planets
Europa
Moons of Gas Planets
Titan
Lakes of liquid methane
Bell Work
8-27-13
What process was responsible for
planet building?
Accretion!!
Part 4: Origin of the Earth,
Atmosphere & Oceans
Formation of Earth’s Crust
Moon Formation
4.6 billion years ago Earth’s crust
was partially melted by:
• asteroid impacts
• gravitational compression
• decay of radioactive elements
Moon’s importance!! Added large amount
of material & radioactive heat to Earth’s
mass. Kept our core molten = magnetic
field.
Formation of Earth’s Crust
Density stratification of the
Earth:
• dense material like iron &
nickel sank to form the
core
Rocky crust
Fe & Ni core
Layered or stratified Earth
• light material like silicates
(SiO2) magnesium, and
aluminum forming the
crust.
Also called the “Iron
Catastrophe”
Formation of the Ancient Atmosphere
Burp!!
SO
H2
O
2
CO
2
Earth's interior was heated primarily from decay of
radioactive elements causing volcanism. Volcanic
eruptions spewed gases from Earth's interior into the
atmosphere, a process called out-gassing. Most of
the gas was carbon dioxide and water vapor.
Formation of Modern Atmosphere
Other
1%
O2
21%
N2
O2
Other
About 3.5 billion years
ago the primitive
atmosphere changed:
CO2 dissolved into young
ocean to form carbonic
acid & combining with
crustal rocks.
N2
78%
Oxygen Revolution
2 billion years ago Earth’s first
ever revolution!! Oxygen began
to accumulate in the atmosphere
with the evolution of plants!!
Burp
O 2!
Stromatalites – blue-green algae
Ancient
Modern
Formation of Ocean Floor
• Two types of Earth’s crust:
– Ocean Crust (basalt)
– Continental Crust (granite)
• Ocean crust is more dense and thinner.
• The tectonic processes formed the sea floor.
Formation of the
Ocean
Forming about 4.2 billion
years ago, the oceans water
originated from:
• Volcanic out-gassing
continued until the
atmosphere contained
~40% water vapor.
• Additional water may have
come from comets.
Earth cooled, water condensed
and formed the oceans.
Out-gassing continues today.
Volcanic out-gassing
from volcanically
active areas like
Yellowstone &
Mammoth Lakes