2 Origin of the Oceans Ibrosenhe/Oceanography/2_Origin_of_the_OceansI.… · Introductory...

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Origin of the Oceans I

Our Solar System

Professor Rosenheim EENS/EBIO 223

Introductory Oceanography

Solar System?

To begin our study of the oceans, we must understand why they exist. Fundamental to this question is whether every planet has oceans, and, if not, why Earth does.



Copernicus• Nicholas Copernicus (1473-1543) liked the heliocentric

system of Aristarchus. He recognized that retrograde motion could be explained by the different times it takes the Earth to Orbit the sun compared to the other planets. Because Mars has a much greater Retrograde motionthan other planets it must be closer than Jupiter and Saturn.

• Copernicus offered two major hypotheses– Planets moved in circular orbits around the Sun– The Earth spins on its axis

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Retrograde Motion



Retrograde Motion



Brahe• After Copernicus’s ideas were published in 1543,

there were many skeptics. One was Tycho Brahe(1546-1601). He established an observatory in Denmark to mark detailed measurements of the planets in order to disprove Copernicus. (There were no telescopes at this time). These were the most accurate measurements on the movements of the planets upto date.

• He hired a mathematician Johannes Kepler to do astronomical calculations and after a while he suspected that Copernicus might be correct. He suspected that some force exerted by the Sun which exerted a control on the planets (this force is gravity but it had not been discovered at this time).

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Kepler• Kepler discovered three laws that describes planetary motions.

– The Law of the Ellipse- The orbit of a planet is described by an ellipse, and is not circular.

– The law of equal areas- A line drawn from the planet to the Sun sweeps out equal areas in equal times. A consequence of this is that a planet moves rapidly when close to the Sun and slower the further away it is.

– The law of orbital harmony- For any planet, the square of the orbital period is proportional to the cube of the planet’s distance from the sun. The period of the Earth is 365.24219 days. (Leap year). The extra .24 days means that every 4 years we add an extra day. In addition every 450 years we need to day a further day.



Galileo• Galileo (1564-1641) constructed a small telescope and

with it made observations which sealed the fate of the geocentric universe. – He observed the rotation of planets around Jupiter (i.e. the Earth

could not be center of the universe) and that Venus went throughphases like the moon which meant that it did not orbit around the Earth, but the Sun.

– Galileo also made observations about force. Motion is a result of a force and will only change if other force is applied. Galileo concluded that a force pulls all bodies with the same acceleration.



Newton• Issac Newton (1642-1727) pulled all the pieces

together. He concluded that the Moon moves around the Earth because it exerts a small force on the Moon which causes it to move towards the Earth. The was the force which Kepler thought might be magnetism. The law of gravity states that every body in the Universe attracts every other body.

• F= G M1M2/ R2.

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Time Scales of Formation of the Universe

• Appearance of Space, Time, and Energy from single point– 5.39X10-44s (expansion to 1.6X10-35m)

• Gravity– 10-43s

• Inflation of Universe to 10cm– 10-32s, still 1027K

• Formation of atoms– 800,000y (Temperature = 3000K)



Formation of a Solar System

• Coalescence of dust and particles– Rotation– Heat– Gravity

• Spinning disc of material– Differentiation of particles

• Coalescence of planetesimal objects and asteroids



Formation of a Solar System

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Planetary formation

• During coalescence of planets, each one was developing unique characteristics– Original nebulas had an abundance of

different elements and some molecules– As planets coalesced and cooled,

gases escaped• Smaller planets lost gases first

– Larger planetesimals created more internal heat and trapped it deep in their cores



Planetary Differentiation

• Result is that each of the nine planets has unique characteristics– (bear in mind that

planetary and solar system formation is an on-going process)



Solar System: SunMass(kg): 1.989 e+30

Mass (earths): 332,830

Eq. radius (km): 695,000

Eq. radius (Earth = 1): 108.97

Mean density (g/cm3): 1.410

Rotational Period (Earth days): 25-36

Escape velocity (km/s): 618.2

Luminosity (erg/s): 3.827e+33

Magnitude (Vo): -26.8

Mean Surface Temperature (oC): 6000

Age (billion years): 4.6

Principal Chemistry (%)Hydrogen: 92.1Helium: 7.8Oxygen: 0.061Carbon: 0.03Nitrogen: 0.0084Neon: 0.0076Iron: 0.0037Silicon: 0.0031Magnesium: 0.0024Sulfur: 0.0015

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The Sun



Life Cycle of a Star

• Energy produced by fusion- joining of two small nuclei to form a larger nucleus plus energy– 2H + 2H = He (two Deuteriums fuse to Helium)

• When Hydrogen is spent, helium fuses to heavier elements (carbon, beryllium, oxygen, etc.)– Temperature requirement is high for this type of

fusion• Eventually star explodes (supernova) and

elements are available to rest of universe



Mature Star – Red Giant

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Over-mature Star – Close to Supernova Event



The Planets: MercuryMass(kg): 3.303 e+23

Mass (earths): 5.5271e-2

Eq. radius (km): 2439.7

Eq. radius (Earth = 1): 3.8252e-1


Mean distance from sun (km): 57,910,000

Mean distance from sun (Earth = 1): 0.3871

Rotational Period (Earth days): 58.6462

Orbital Period (days): 87.969

Mean orbital velocity (km/s): 47.88


Maximum Surface Temperature (oC): 427

Minimum Surface Temperature (oC): -173

Atmosphere componentsHeliumSodiumOxygen



The Planets: VenusMass(kg): 4.689e+24

Mass (earths): 0.81476





Mean distance from the sun (Earth = 1): 0.7233

Rotational Period (Earth days): -243.0187




Atmospheric pressure (bars): 92

Atmosphere componentsCarbon dioxide (96%)Nitrogen (3+%)trace amounts of sulfur dioxide, water vapor, carbon monoxide, argon, helium, neon, hydrogen chloride, hydrogen flouride

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The Planets: EarthMass(kg): 5.976e+24

Mass (earths): 1

Eq. radius (km): 6378

Eq. radius (Earth = 1): 1



Mean distance from the sun (Earth = 1): 1

Rotational Period (days): 0.99727

Rotational Period (hours): 23.9345




Atmospheric pressure (bars): 1.013

Atmosphere componentsNitrogen (77%)Oxygen (21%)



Earth’s Peculiarities

• Rotation of Earth causes it to bulge at center (equator)



Important Elements Differentiated during Earth’s Formation

• Elemental radiometric clocks –– Uranium– Thorium

• Radioactively unstable– Parents decay into daughters– If we know the rate of decay and the initial

composition of the daughters, we know the age of a substance

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Formation of Water on Earth

• Hot gases of newly formed compounds escaped the solid earth, trapped by gravity, and condensed when cooled



Important Elements Differentiated during Earth’s Formation

• Water – H2O!– Very important to

• Life• Weather• Habitability of Planet Earth

• Water formed on other planets– What form?– Did it stay?



Life on Mars?

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Life on Mars?



The Planets: MarsMass(kg): 6.421e+23

Mass (earths): 1.0745e-1


Eq. radius (Earth = 1): 5.3264e-1







Minimum Surface Temperature (OC): -140

Mean Surface Temperature (oC): -63

Maximum Surface Temperature (oC): 20


Atmosphere componentsCarbon dioxide (95.32%)Nitrogen (2.7)Argon (1.6)Oxygen (0.2)Carbon Monoxide (0.7)Water, Neon, Krypton, Xenon, Ozone



Did Mars Have Water?

• Mars Rover Program (NASA)

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Did Mars Have Water?

• If so, what happened to it?



The Outer Planets: JupiterMass(kg): 1.9e+27

Mass (earths): 3.1794e2

Eq. radius (km): 71492







Mean Orbital Velocity (km/s): 13.07

Mean Cloud Temperature (oC): -121


Atmosphere componentsHydrogen (90%)Helium (10%)



The Outer Planets: SaturnMass(kg): 5.688e+26



Eq. radius (Earth = 1): 9.4494e0


Mean distance from sun (km): 1,429,400,000



Orbital Period (years): 29.458




Atmosphere componentsHydrogen (87%)Helium (13%)

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Moons of Saturn and Jupiter

Jupiter:63 moonsDiameter of Ganymede = 0.4(Earth)

Saturn:60 moonsRings are gravitationally trapped debris



The Outer Planets: UranusMass(kg): 8.686e+25

Mass (earths): 14.5






Rotational Period (hours): -17.9





Atmosphere componentsHydrogen (83%)Helium (15%)Methane (2%)



The Outer Planets: NeptuneMass(kg): 1.024e+26










Mean Cloud Temperature (oC): -193 to -153

Atmospheric pressure (bars): 1-3

Atmosphere componentsHydrogen (85%)Helium (13%)Methane (2%)

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Pluto – Planet or Not?

• Pluto and moon, Charon, are a binary system

• Other objects in the Kuiper belt are larger

• Recognition based in revolution plane of Neptune



Summary• There is one water planet – Earth• Planetary formation differentiated

elements each planet contains• Earth and Venus are very similar• Mars once had water, evidenced by latest

research• The Outer Gaseous Planets are very

different from the Rocky Inner Planets



Summary

• Scientific Notation!

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