Transcript Cell Physiology

Oceanography, An Invitation to Marine Science | 9e
Tom Garrison
1
The Origin of the Ocean
© 2016 Cengage Learning. All Rights Reserved.
Key Concepts
• Science is a systematic process of asking
questions about the observable world by
gathering and then studying information
• The universe’s observable mass consists
mostly of hydrogen atoms
– The heavy elements we see around us were
constructed in stars
• Earth is density stratified
– Earth’s first solid surface formed about 4.6
billion years ago
© 2016 Cengage Learning. All Rights Reserved.
Key Concepts (cont’d.)
• Life probably originated in the ocean
shortly after it formed
• Water, even liquid water, appears to be
present in other places in our solar system
© 2016 Cengage Learning. All Rights Reserved.
1.1 Earth Is an Ocean World
•
•
•
•
Oceanography – story of the ocean
Liquid water can exist on Earth
Ocean – body of saline water
Single world ocean – Earth’s oceans are
connected
© 2016 Cengage Learning. All Rights Reserved.
1.2 Marine Scientists Use the Logic of
Science to Study the Ocean
• Science – systematic process of asking
questions, gathering and interpreting data
• Hypothesis – speculation that can be
tested
• Experiment – test that simplifies
observation in nature
• Theory – statement that explains
observations
• Scientific method – process
© 2016 Cengage Learning. All Rights Reserved.
A Logical Series of Steps Can Represent
the Procedure of Science
© 2016 Cengage Learning. All Rights Reserved.
1.3 Stars Form Seas
• The big bang occurred about 13.7 billion
years ago
• Stars formed early in the history of the
universe
– About a million years after the big bang
temperatures were cool enough for atoms
– About a billion years after the big bang stars
and galaxies could form
© 2016 Cengage Learning. All Rights Reserved.
Stars and Galaxies
• Stars and planets are contained within
galaxies
– We live in the Milky Way galaxy
– Stars – spheres of incandescent gases
– Star and family of planets – solar system
• Stars make heavy elements from lighter
ones:
– By fusing hydrogen into helium
– From dying stars – supernovae
© 2016 Cengage Learning. All Rights Reserved.
The Dispersion of Heavy Elements
© 2016 Cengage Learning. All Rights Reserved.
Solar Systems
• Solar systems form by accretion
– Particles clump together to form larger
masses
– Heavier elements are concentrated closer to
the sun
– Lighter elements make up the outer planets
© 2016 Cengage Learning. All Rights Reserved.
1.4 Earth, Ocean, and Atmosphere
Accumulated in Layers Sorted by Density
• Density stratification – gravity pulls heavier
elements towards the center of an object,
lighter elements rise to the outside
• The first surface formed about 4.6 billion
years ago
• Earth’s moon formed from a collision of
Earth and another planetary body
– About 4.4 billion years ago
© 2016 Cengage Learning. All Rights Reserved.
A Representation of the Formation of Earth
© 2016 Cengage Learning. All Rights Reserved.
Lighter
matter and
silicates
Iron
© 2016 Cengage Learning. All Rights Reserved.
Stepped Art
Earth’s First Atmosphere
• Earth’s first atmosphere was stripped
away by radiation from the sun
• Vapors came from inside the planet –
outgassing
• Water vapor existed in the atmosphere
– Eventually cooled to form clouds and
precipitated to the surface
• Early ocean and atmosphere different from
today
© 2016 Cengage Learning. All Rights Reserved.
1.5 Life Probably Originated in the Ocean
• Biosynthesis – formation of living
organisms from simple organic building
blocks
– Unlikely to occur today
– Conditions on the young Earth were
sufficiently different
• Oldest fossils 3.4 to 3.5 billion years old
– Remains of bacteria-like organisms
© 2016 Cengage Learning. All Rights Reserved.
One of the Oldest Fossils Ever Discovered
© 2016 Cengage Learning. All Rights Reserved.
1.6 What Will Be Earth’s Future?
• The sun will begin to die in around 5 billion
years
– Red giant phase will engulf the inner planets
in solar atmosphere
– Earth will be recycled
© 2016 Cengage Learning. All Rights Reserved.
1.7 Are There Other Ocean Worlds?
• Water is not scarce in the solar system
• Jupiter and Mars contain ice
• Liquid water exists on Jupiter’s moons,
Europa and Ganymede, underneath crusts
of ice
• Liquid water could exist on Saturn’s moon
Enceladus
© 2016 Cengage Learning. All Rights Reserved.
Is There Evidence of Water on Other
Planets?
• Mars may have had an ocean in the
distant past
– Evidence for water erosion on the surface
– Water could have frozen beneath the surface
as the planet lost its atmosphere
• Saturn’s moon, Titan, has a liquid ocean of
hydrocarbons
• Water could exist on extrasolar planets
© 2016 Cengage Learning. All Rights Reserved.
Evidence of a Once-Wet Mars
© 2016 Cengage Learning. All Rights Reserved.
Chapter In Perspective
• We study our planet using the scientific
method
• Atoms that make up Earth and the solar
system were formed in stars
• Earth formed from accretion 4.6 billion
years ago and became density stratified
• Life probably originated in the ocean
• No other planet in the solar system has a
liquid ocean on the surface
© 2016 Cengage Learning. All Rights Reserved.
Some Questions from Students
• Could life have formed on other planets in
our solar system?
• If so, would life on these planets resemble
life on Earth?
© 2016 Cengage Learning. All Rights Reserved.