Origin of Solar System & Origin of Solar System & EarthEarth

Chapter 2

What does this have to do with What does this have to do with oceanography?oceanography?

Where does water come from?Where does water come from? Why do we have oceans?Why do we have oceans? Why do we have life as we know it?Why do we have life as we know it? Elemental compositionElemental composition Present day configuration relative to originsPresent day configuration relative to origins Hydrological cycleHydrological cycle Dissolved gases/Ocean and AtmosphereDissolved gases/Ocean and Atmosphere

TimeTime

Importance of time scalesImportance of time scales Forces at work in the pastForces at work in the past Forces at work todayForces at work today How can we measure age of the earthHow can we measure age of the earth

How old is Earth?How old is Earth?

Biblical scholars of 19Biblical scholars of 19thth century (Bishop Ussher) – century (Bishop Ussher) – 6000 years (started at 4004 BC)6000 years (started at 4004 BC)

Classical Greeks – infinite – history endlessly Classical Greeks – infinite – history endlessly repeats itselfrepeats itself

Mayans believed earth recycled on a 3000 year Mayans believed earth recycled on a 3000 year time scaletime scale

Han Chinese thought earth was recreated every Han Chinese thought earth was recreated every 23,639,040 years 23,639,040 years

The age we now except may change but is The age we now except may change but is consistent with current theoryconsistent with current theory

More recent effortsMore recent efforts

Lord Kelvin - 80 million years old – based on Lord Kelvin - 80 million years old – based on cooling of molten Earthcooling of molten Earth

Darwin - really old based on time for natural Darwin - really old based on time for natural selection (biological argument)selection (biological argument)

Hutton – really old based on Hutton – really old based on uniformitarianism (processes in the past uniformitarianism (processes in the past taking place at rates comparable to today) taking place at rates comparable to today) (geological argument)(geological argument)

Earth’s ageEarth’s age

Earth is about 4.5 (or 4.6) BY oldEarth is about 4.5 (or 4.6) BY old First 700 MY Earth was a spinning cloud of First 700 MY Earth was a spinning cloud of

gas, dust and planetoidsgas, dust and planetoids These condensed and settled to solidify into These condensed and settled to solidify into

a series of planetsa series of planets Since that time, geological history and Since that time, geological history and

evolution commenced.evolution commenced.

The Big Bang TheoryThe Big Bang Theory Currently the dominant theoryCurrently the dominant theory First iteration proposed by Georges LemaFirst iteration proposed by Georges Lemaîître in tre in

1927. He observed the red shift in distant nebulas 1927. He observed the red shift in distant nebulas and invoked relativity.and invoked relativity.

Hubble found experimental evidence (1929) – Hubble found experimental evidence (1929) – galaxies are moving away from us with speeds galaxies are moving away from us with speeds proportional to their distance.proportional to their distance.

Theory suggested because it explains the Theory suggested because it explains the expansion & predicts the existence of cosmic expansion & predicts the existence of cosmic radiation (leftover photons) & nucleosynthesisradiation (leftover photons) & nucleosynthesis

1964 cosmic radiation discovered (Arno Penzias & 1964 cosmic radiation discovered (Arno Penzias & Robert Wilson who won the Nobel Prize)Robert Wilson who won the Nobel Prize)

Big Bang – what is it?Big Bang – what is it?

All mass and energy concentrated at a geometric All mass and energy concentrated at a geometric pointpoint

~14 or 15 BY ago~14 or 15 BY ago Beginning of space and timeBeginning of space and time Expansion/cooling of universe beganExpansion/cooling of universe began Protons and neutrons formProtons and neutrons form Cooling initiated the formation of atoms Cooling initiated the formation of atoms

((nucleosynthesisnucleosynthesis) – first mostly H (the most ) – first mostly H (the most abundant form of matter in the universe)abundant form of matter in the universe)

Formation of galaxy and starsFormation of galaxy and stars

Galaxy – rotating aggregation of stars, dust, gas Galaxy – rotating aggregation of stars, dust, gas and debris held together by gravityand debris held together by gravity

Stars are massive spheres of incandescent gasesStars are massive spheres of incandescent gases 100’s of billions of galaxies in the universe and 100’s of billions of galaxies in the universe and

100’s of billions of stars in the galaxies100’s of billions of stars in the galaxies Sun is a starSun is a star Sun plus its family of planets is our solar systemSun plus its family of planets is our solar system Our solar system formed about 5 BY agoOur solar system formed about 5 BY ago

Our galaxy is out in a spiral armOur galaxy is out in a spiral arm Our solar system orbits the galaxy’s coreOur solar system orbits the galaxy’s core

– (230 million year orbit at 280 km/s)(230 million year orbit at 280 km/s)

StarsStars

Stars form in nebulae, large diffuse clouds of dust Stars form in nebulae, large diffuse clouds of dust and gas.and gas.

Condensation theory – spinning nebula starts to Condensation theory – spinning nebula starts to shrink and heat under its own gravityshrink and heat under its own gravity

Protostar – condensed gasesProtostar – condensed gases At temperature of ~10 million degrees C, nuclear At temperature of ~10 million degrees C, nuclear

fusion begins (H’s fuse to form He) which releases fusion begins (H’s fuse to form He) which releases energy and stops shrinkageenergy and stops shrinkage

Star is stable once fusion reactions begin (form Star is stable once fusion reactions begin (form atoms as heavy as C and O)atoms as heavy as C and O)

Beginning of the endBeginning of the end

Star starts consuming heavier atoms Star starts consuming heavier atoms increasing energy output and swelling to a increasing energy output and swelling to a “red giant”“red giant”

Incinerates planet and throws off matter Incinerates planet and throws off matter including heavy elementsincluding heavy elements

More massive stars get hotter and consume More massive stars get hotter and consume H at higher rates and make heavier atoms H at higher rates and make heavier atoms (e.g., Fe)(e.g., Fe)

The endThe end

H is consumedH is consumed Core collapses on itselfCore collapses on itself Internal temperatures sore so can no longer Internal temperatures sore so can no longer

contractcontract Cataclysmic expansion called a supernova (30 Cataclysmic expansion called a supernova (30

sec)sec) Mass is accelerated outwardMass is accelerated outward Forces holding apart atomic nuclei are overcomeForces holding apart atomic nuclei are overcome Heavier atoms formedHeavier atoms formed

Our Solar SystemOur Solar System

Our solar nebula was struck by a supernovaOur solar nebula was struck by a supernova Caused our condensing nebula to spinCaused our condensing nebula to spin Introduced heavy atoms to seed the formation of Introduced heavy atoms to seed the formation of

planetsplanets 5 BY ago, the solar nebula was 75% H, 23% He 5 BY ago, the solar nebula was 75% H, 23% He

and 2% other materialand 2% other material Center became protosunCenter became protosun Outer material became planets – smaller bodies Outer material became planets – smaller bodies

that orbit a star but do not shine by their own lightthat orbit a star but do not shine by their own light

PlanetsPlanets Grew by accretion – big clumps use gravitational pull to accrete Grew by accretion – big clumps use gravitational pull to accrete

condensing mattercondensing matter Near sun, first materials to solidify had higher boiling points (metals Near sun, first materials to solidify had higher boiling points (metals

and rocky minerals) – Mercury is mostly Fe, Ni. Inner rocky planets.and rocky minerals) – Mercury is mostly Fe, Ni. Inner rocky planets. Next Mg, Si, HNext Mg, Si, H22O and OO and O22 condensed (plus some Fe and Ni). Middle condensed (plus some Fe and Ni). Middle

planets (e.g., Earth).planets (e.g., Earth). CHCH44 and NH and NH33 in frigid outer zones. Outer gassy planets (Jupiter, in frigid outer zones. Outer gassy planets (Jupiter,

Saturn, Uranus and Neptune).Saturn, Uranus and Neptune).

Stabilization of solar systemStabilization of solar system Protosun became star (sun) and nuclear fusion Protosun became star (sun) and nuclear fusion

beganbegan Solar wind (radiation) at the start of those Solar wind (radiation) at the start of those

reactions cleared excess particles and ended reactions cleared excess particles and ended rapid accretion of inner planets.rapid accretion of inner planets.

Early EarthEarly Earth Homogeneous throughout during initial accretion of cold particlesHomogeneous throughout during initial accretion of cold particles Surface heated by impacts (asteroids, comets and debris)Surface heated by impacts (asteroids, comets and debris) Heat, gravitational compression, radioactive decay caused partial melting.Heat, gravitational compression, radioactive decay caused partial melting. Density stratification.Density stratification.

Gravity pulled heavy Gravity pulled heavy

elements to interior.elements to interior. Friction during this Friction during this

produced more heat.produced more heat. Lighter minerals (Si, Lighter minerals (Si,

Mg, Al and O-bonded Mg, Al and O-bonded

compounds) migrated to compounds) migrated to

surface forming Earth’s surface forming Earth’s

crust.crust.

LaterLater

Earth began to cool (first surface 4.6 BY Earth began to cool (first surface 4.6 BY ago)ago)

Impact of planetary body (4.5 BY ago – Impact of planetary body (4.5 BY ago – metallic core fell into earth’s core and rocky metallic core fell into earth’s core and rocky mantle was ejected, condensed and formed mantle was ejected, condensed and formed our moon.our moon.

New atmosphere formed by outgassingNew atmosphere formed by outgassing Hot vapor condensed to clouds (water)Hot vapor condensed to clouds (water) Comet impacts added additional waterComet impacts added additional water

Formation of liquid waterFormation of liquid water

Outgassing & cooling to form boiling rain (20 million Outgassing & cooling to form boiling rain (20 million years)years)

Additional cooling – water collected in basinsAdditional cooling – water collected in basins Water plus COWater plus CO22 made carbonic acid which dissolved made carbonic acid which dissolved

rocks (contributed salts)rocks (contributed salts) More water from comets (~ meters in diameter)More water from comets (~ meters in diameter) Carbonaceous chondrites?Carbonaceous chondrites? Later, addition of OLater, addition of O22 caused oxidation reactions. caused oxidation reactions. Most of the ocean in place by 4 BY agoMost of the ocean in place by 4 BY ago

– (new water is 0.1 km(new water is 0.1 km33/yr)/yr)– Unclear whether there were always continentsUnclear whether there were always continents

Gases expelled (outgassed) from volcanos formed new Earth atmosphere.

•Composed mostly of CO2

and water vapor. •Clouds reflected about 60% of sunlight. •Clouds trapped lots of energy as well.

Water began accumulating in liquid form about 4.0 BYA forming earliest terrestrial oceans.

Widespread volcanic activity released H2 and smaller quantities of CO2, Cl2, N2 and

H2 which produced a water vapor atmosphere that also contained carbon dioxide

(CO2), methane (CH4) and ammonia (NH3).

As Earth cooled, the water vapor (1) condensed and (2) fell to Earth's surface. There it accumulated to (3) form the oceans.

Volume of Earth's mantle is 1027 cm3 (ave. density of 4.5 g/cm3).

Total mass for mantle is 4.5 X 1027 g.

Water of oceans has mass of 1.4 X 1024 g.

Mantle lost 0.031% of mass as water to have produced oceans.

Water from comets -measure about 9 m (30 ft) in diameter. -enter atmosphere at rate of about 20/second.

At the observed rate of occurrence, Earth would receive 0.0025 mm of water per year. Four billion years of such bombardment would give enough water to fill the oceans to their present volume.

Recorded by ultraviolet photometer aboard the satellite Dynamic Explorer 1. The dark spot or 'hole', thought to be caused by the vaporization of cometlike balls of ice, is shown in the inset. The dark holes in the atmosphere were 48 km across and existed for up to 3 minutes. Because of the absorption spectra of these dark spots, they can be explained only by the comet-like balls of ice breaking up and vaporizing 1600-3200 km above Earths surface.

Current Ocean StatisticsCurrent Ocean Statistics

97.5 % of water on earth is in the ocean97.5 % of water on earth is in the ocean 2.5 % of water is on land (primarily as ice)2.5 % of water is on land (primarily as ice) 0.01% is surface0.01% is surface

and atm water!and atm water!

More statsMore stats

Total area of oceans now is 71% of Earth’s Total area of oceans now is 71% of Earth’s surfacesurface

Avg depth is 3800 mAvg depth is 3800 m Mean sphere depth is 2430 m Mean sphere depth is 2430 m

– depth at which amount of surface above and depth at which amount of surface above and below that depth are equalbelow that depth are equal

Avg temperature is 4Avg temperature is 4ooC (= 39C (= 39ooF; cold)F; cold) Volume 1.4 billion kmVolume 1.4 billion km33

Early AtmosphereEarly Atmosphere 4.5 to 3.5 BY ago. Rich in CO4.5 to 3.5 BY ago. Rich in CO22, N, N22, H, H22O and some CHO and some CH44 and NH and NH33.. 3.5 BY ago began shift toward today’s atmosphere (mostly O3.5 BY ago began shift toward today’s atmosphere (mostly O22 and CO and CO22)) Chemical weathering: COChemical weathering: CO22 dissolves in SW to make carbonic acid (acid dissolves in SW to make carbonic acid (acid

dissolved rocks releasing minerals) & photochemical reactions with dissolved rocks releasing minerals) & photochemical reactions with atmospheric Hatmospheric H22OO

About 2 BY ago, getAbout 2 BY ago, get

introduction of Ointroduction of O22 into into

atmosphere (after atmosphere (after oxidation reactions).oxidation reactions). Current atmCurrent atm

- 21% O- 21% O22

- 78% N- 78% N22

- 0.04% CO- 0.04% CO22

~0.9% Argon~0.9% Argon

Origin of LifeOrigin of Life

~ 3.5 BY ago~ 3.5 BY ago Definition – self-replication?Definition – self-replication?

– Capable of growing more complex; obtains energy by Capable of growing more complex; obtains energy by breaking down chemical compoundsbreaking down chemical compounds

Water is ideal medium for life (retains heat, moderates Water is ideal medium for life (retains heat, moderates temperature, dissolves chemicals, transports nutrients)temperature, dissolves chemicals, transports nutrients)

Source of building blocksSource of building blocks– Primordial soup (mixture of HPrimordial soup (mixture of H22Ovapor, NHOvapor, NH33, CH, CH44 and H) and H)– Extraterrestrial – meteorites & cometsExtraterrestrial – meteorites & comets

Carbonaceous chondrites have C in the form of organic compounds Carbonaceous chondrites have C in the form of organic compounds including amino acidsincluding amino acids

Becoming an organismBecoming an organism

Need building blocks plus energyNeed building blocks plus energy Surface pools – biosynthesisSurface pools – biosynthesis

– Concentration of organic matter on surfaces of Concentration of organic matter on surfaces of clay minerals or bubbles; energy from sunlightclay minerals or bubbles; energy from sunlight

Deep oceanDeep ocean– Geothermal energy supplied by hydrothermal Geothermal energy supplied by hydrothermal

vents and Hvents and H22SS

Oldest known fossil (3.5 BY) from NW AustraliaOldest known fossil (3.5 BY) from NW Australia Life altered the atmosphereLife altered the atmosphere First bacteria – anaerobicFirst bacteria – anaerobic Green algae – evolved from Green algae – evolved from cyanobacteriacyanobacteria

– Photosynthesis Photosynthesis

uses COuses CO22 and and

evolves Oevolves O22

Stromatolites – Stromatolites – clusters of algaeclusters of algae

Oscillatoria today

First fossil life – bacteria-like forms (>3.8 BY ago).

•Earliest forms were heterotrophs (organic compounds). •Autotrophs eventually evolved (Oxidized inorganic compounds through chemosynthesis).

Fossil algae 2 billion years old (left) and living algae (right). Note the similarities in appearance. Interspersed among the living algae are chains of rod-shaped bacteria.

Photosynthesis:

6H2O + 6CO2 + Sunlight <---> C6H12O6 + 6O2

Two billion year old fossilized stromatolites from the shores of Great Slave Lake, North-West Territories, Canada.

Fate of early atmosphereFate of early atmosphere

Green plants produced OGreen plants produced O22 and removed CO and removed CO22

C from air became locked up in sedimentary C from air became locked up in sedimentary rocks and dissolved into the oceansrocks and dissolved into the oceans

NHNH33 and CH and CH44 reacted with atmospheric O reacted with atmospheric O22

NN22 was released from reactions of NH was released from reactions of NH33 with O with O22 and from denitrifying bacteria.and from denitrifying bacteria.

OO22 built up forming ozone (filtering out UV rays built up forming ozone (filtering out UV rays and allowing more evolution)and allowing more evolution)

Timeline (since big bang)Timeline (since big bang)

1010-35-35 sec ABB (The Big Bang) sec ABB (The Big Bang)– The universe is an infinitely dense, hot fireball.The universe is an infinitely dense, hot fireball.

1010-6-6 sec ABB (1 millionth of a second) sec ABB (1 millionth of a second)– Universe forms: Expansion slows down; universe cools Universe forms: Expansion slows down; universe cools

and becomes less denseand becomes less dense– The most basic forces in nature become distinct: first The most basic forces in nature become distinct: first

gravity, then the strong force, which holds nuclei of atoms gravity, then the strong force, which holds nuclei of atoms together, followed by the weak and electromagnetic together, followed by the weak and electromagnetic forces. By the first second, the universe is made up of forces. By the first second, the universe is made up of fundamental particles and energy: quarks, electrons, fundamental particles and energy: quarks, electrons, photons, neutrinos and less familiar types. These photons, neutrinos and less familiar types. These particles smash together to form protons and neutrons.particles smash together to form protons and neutrons.

3 sec ABB3 sec ABB– Formation of basic elementsFormation of basic elements– Protons and neutrons come together to form the nuclei of Protons and neutrons come together to form the nuclei of

simple elements: hydrogen (1 proton), helium (2 protons) simple elements: hydrogen (1 proton), helium (2 protons) and lithium (3 protons) (1, 2 and 3 in periodic table). It will and lithium (3 protons) (1, 2 and 3 in periodic table). It will take another 300,000 years for electrons to be captured take another 300,000 years for electrons to be captured into orbits around these nuclei to form stable atoms. into orbits around these nuclei to form stable atoms.

10,000 yr ABB10,000 yr ABB– Radiation EraRadiation Era– The first major era in the history of the universe is one in The first major era in the history of the universe is one in

which most of the energy is in the form of radiation -- which most of the energy is in the form of radiation -- different wavelengths of light, X rays, radio waves and different wavelengths of light, X rays, radio waves and ultraviolet rays. This energy is the remnant of the ultraviolet rays. This energy is the remnant of the primordial fireball, and as the universe expands, the waves primordial fireball, and as the universe expands, the waves of radiation are stretched and diluted until today, they of radiation are stretched and diluted until today, they make up the faint glow of microwaves which bathe the make up the faint glow of microwaves which bathe the entire universe. entire universe.

300,000 yr ABB300,000 yr ABB– Matter dominatesMatter dominates– The energy in matter and the energy in radiation are The energy in matter and the energy in radiation are

equal. As universe expands, waves of light are equal. As universe expands, waves of light are stretched to lower and lower energy, while the matter stretched to lower and lower energy, while the matter travels onward largely unaffected. Neutral atoms are travels onward largely unaffected. Neutral atoms are formed as electrons link up with hydrogen and helium formed as electrons link up with hydrogen and helium nuclei. Microwave background radiation gives us a nuclei. Microwave background radiation gives us a direct picture of how matter was distributed at this early direct picture of how matter was distributed at this early time. time.

300 MY ABB300 MY ABB– Birth of stars and galaxies.Birth of stars and galaxies.– Gravity amplifies slight irregularities in the density of the Gravity amplifies slight irregularities in the density of the

primordial gas. Even as the universe continues to primordial gas. Even as the universe continues to expand rapidly, pockets of gas become more and more expand rapidly, pockets of gas become more and more dense. Stars ignite within these pockets, and groups of dense. Stars ignite within these pockets, and groups of stars become the earliest galaxies. (Still perhaps 12 to stars become the earliest galaxies. (Still perhaps 12 to 15 billion years before the present). 15 billion years before the present).

5 BY ago Birth of the Sun5 BY ago Birth of the Sun– The sun forms within a cloud of gas in a spiral arm of the Milky Way The sun forms within a cloud of gas in a spiral arm of the Milky Way

Galaxy. A vast disk of gas and debris that swirls around this new star Galaxy. A vast disk of gas and debris that swirls around this new star gives birth to planets, moons, and asteroids . Earth is the third planet out.gives birth to planets, moons, and asteroids . Earth is the third planet out.

– The image on the left, from the Hubble Space Telescope, shows a The image on the left, from the Hubble Space Telescope, shows a newborn star in the Orion Nebula surrounded by a disk of dust and newborn star in the Orion Nebula surrounded by a disk of dust and gas that may one day collapse into planets, moons and asteroids. gas that may one day collapse into planets, moons and asteroids.

3.8 BY ago Earliest Life3.8 BY ago Earliest Life– The Earth has cooled and an atmosphere develops. Microscopic living The Earth has cooled and an atmosphere develops. Microscopic living

cells, neither plants nor animals, begin to evolve and flourish in earth's cells, neither plants nor animals, begin to evolve and flourish in earth's many volcanic environments. many volcanic environments.

700 MY ago Primitive Animals appear700 MY ago Primitive Animals appear– These are mostly flatworms, jellyfish and algae. By 570 million years These are mostly flatworms, jellyfish and algae. By 570 million years

before the present, large numbers of creatures with hard shells before the present, large numbers of creatures with hard shells suddenly appear. suddenly appear.

200 MY ago Mammals appear200 MY ago Mammals appear– The first mammals evolved from a class of reptiles that evolved The first mammals evolved from a class of reptiles that evolved

mammalian traits, such as a segmented jaw and a series of bones that mammalian traits, such as a segmented jaw and a series of bones that make up the inner ear. make up the inner ear.

65 MY ago Dinosaurs become extinct65 MY ago Dinosaurs become extinct– An asteroid or comet slams into the northern part of the Yucatan Peninsula An asteroid or comet slams into the northern part of the Yucatan Peninsula

in Mexico. This world-wide cataclysm brings to an end the long age of the in Mexico. This world-wide cataclysm brings to an end the long age of the dinosaurs, and allows mammals to diversify and expand their ranges. dinosaurs, and allows mammals to diversify and expand their ranges.

600,000 yr ago 600,000 yr ago Homo sapiensHomo sapiens evolve evolve– Our earliest ancestors evolve in Africa from a line of creatures that Our earliest ancestors evolve in Africa from a line of creatures that

descended from apes. descended from apes.

170,000 yr ago Supernova 1987a explodes170,000 yr ago Supernova 1987a explodes– A star explodes in a dwarf galaxy known as the Large Magellanic A star explodes in a dwarf galaxy known as the Large Magellanic

Cloud that lies just beyond the Milky Way. The star, known in modern Cloud that lies just beyond the Milky Way. The star, known in modern times as Sanduleak 69-202, is a blue supergiant 25 times more times as Sanduleak 69-202, is a blue supergiant 25 times more massive than our Sun. Such explosions distribute all the common massive than our Sun. Such explosions distribute all the common elements such as Oxygen, Carbon, Nitrogen, Calcium and Iron into elements such as Oxygen, Carbon, Nitrogen, Calcium and Iron into interstellar space where they enrich clouds of Hydrogen and Helium interstellar space where they enrich clouds of Hydrogen and Helium that are about to form new stars. They also create the heavier that are about to form new stars. They also create the heavier elements (such as gold, silver, lead, and uranium) and distribute elements (such as gold, silver, lead, and uranium) and distribute these as well. Their remnants generate the cosmic rays which lead to these as well. Their remnants generate the cosmic rays which lead to mutation and evolution in living cells. These supernovae, then, are mutation and evolution in living cells. These supernovae, then, are key to the evolution of the Universe and to life itself.key to the evolution of the Universe and to life itself.

1054 Crab Supernova appears1054 Crab Supernova appears– A new star in the constellation Taurus outshines Venus. Chinese, A new star in the constellation Taurus outshines Venus. Chinese,

Japanese, and Native American observers record the appearance Japanese, and Native American observers record the appearance of a supernova. It is not, however, recorded in Europe, most likely of a supernova. It is not, however, recorded in Europe, most likely as a consequence of lack of study of nature during the Dark Ages. as a consequence of lack of study of nature during the Dark Ages. The remnants of this explosion are visible today as the Crab The remnants of this explosion are visible today as the Crab Nebula. Within the nebula, astronomers have found a pulsar, the Nebula. Within the nebula, astronomers have found a pulsar, the ultra-dense remains of a star that blew up. ultra-dense remains of a star that blew up.

1609 Galileo builds first telescope1609 Galileo builds first telescope– Five years after the appearance of the great supernova of 1604, Five years after the appearance of the great supernova of 1604,

Galileo builds his first telescope. He sees the moons of Jupiter, Galileo builds his first telescope. He sees the moons of Jupiter, Saturn's rings, the phases of Venus, and the stars in the Milky Way. Saturn's rings, the phases of Venus, and the stars in the Milky Way.

1665 Newton describes gravity1665 Newton describes gravity At the age of 23, young Isaac Newton realizes that At the age of 23, young Isaac Newton realizes that

gravitational force accounts for falling bodies on earth as well gravitational force accounts for falling bodies on earth as well as the motion of the moon and the planets in orbit. This is a as the motion of the moon and the planets in orbit. This is a revolutionary step in the history of thought, as it extends the revolutionary step in the history of thought, as it extends the influence of earthly behavior to the realm of the heavens. One influence of earthly behavior to the realm of the heavens. One set of laws, discovered and tested on our planet, will be seen set of laws, discovered and tested on our planet, will be seen to govern the entire universe. to govern the entire universe.

1905 Einstein’s Theory of Relativity1905 Einstein’s Theory of RelativityRelativity recognizes the speed Relativity recognizes the speed

of light as the of light as the absolute speed limit in the absolute speed limit in the universe and, as such, universe and, as such, unites the previously separate unites the previously separate concepts of space concepts of space and time into a unified and time into a unified spacetime. Eleven years spacetime. Eleven years later, his General later, his General Theory of Relativity replaces Theory of Relativity replaces Newton's model of Newton's model of gravity with one in which the gravity with one in which the gravitational force is gravitational force is interpreted as the response interpreted as the response of bodies to distortions of bodies to distortions in spacetime which matter in spacetime which matter itself creates. itself creates. Predictions of black holes and an Predictions of black holes and an expanding expanding Universe are immediate Universe are immediate consequences of this consequences of this revolutionary theory which revolutionary theory which remains unchallenged remains unchallenged today as our description of today as our description of the cosmos. the cosmos.

1929 Hubble discovers universe is expanding1929 Hubble discovers universe is expanding– Edwin Hubble discovers that the universe is expanding. The astronomer Edwin Hubble discovers that the universe is expanding. The astronomer

Edwin Hubble uses the new 100-inch telescope on Mt. Wilson in Southern Edwin Hubble uses the new 100-inch telescope on Mt. Wilson in Southern California to discover that the farther away a galaxy is, the more its light California to discover that the farther away a galaxy is, the more its light is shifted to the red. And the redder a galaxy's light, the faster it is moving is shifted to the red. And the redder a galaxy's light, the faster it is moving away from us. By describing this "Doppler shift," Hubble proves that the away from us. By describing this "Doppler shift," Hubble proves that the universe is not static, but is expanding in all directions. He also discovers universe is not static, but is expanding in all directions. He also discovers that galaxies are much further away than anyone had thought. that galaxies are much further away than anyone had thought.

1960 Quasars discovered1960 Quasars discovered– Allan Sandage and Thomas Matthews find sources of intense radio Allan Sandage and Thomas Matthews find sources of intense radio

energy, calling them Quasi Stellar Radio Sources. Four years later, energy, calling them Quasi Stellar Radio Sources. Four years later, Maarten Schmidt would discover that these sources lie at the edge of Maarten Schmidt would discover that these sources lie at the edge of the visible universe. In recent years, astronomers have realized that the visible universe. In recent years, astronomers have realized that they are gigantic black holes at the centers of young galaxies into they are gigantic black holes at the centers of young galaxies into which matter is heated to high temperatures and glows brightly as it which matter is heated to high temperatures and glows brightly as it rushes in. rushes in.

1964 Microwave radiation discovered1964 Microwave radiation discovered– Scientists at the Bell Telephone Laboratories discovered microwave Scientists at the Bell Telephone Laboratories discovered microwave

radiation that bathes the earth from all directions in space. This radiation that bathes the earth from all directions in space. This radiation is the afterglow of the Big Bang.radiation is the afterglow of the Big Bang.

1967 Discovery of Pulsars1967 Discovery of Pulsars– A graduate student, Jocelyn Bell, and her professor, A graduate student, Jocelyn Bell, and her professor,

Anthony Hewish, discover intense pulsating sources of Anthony Hewish, discover intense pulsating sources of radio energy, known as pulsars. Pulsars were the first radio energy, known as pulsars. Pulsars were the first known examples of neutron stars, extremely dense known examples of neutron stars, extremely dense objects that form in the wake of some supernovae. The objects that form in the wake of some supernovae. The crab pulsar, is the remnant of the bright supernova crab pulsar, is the remnant of the bright supernova recorded by Native Americans and cultures around the recorded by Native Americans and cultures around the world in the year 1054 A.D.world in the year 1054 A.D.

1987 Light from supernova 1987 reaches Earth1987 Light from supernova 1987 reaches Earth– The light from this supernova reaches earth, 170,000 The light from this supernova reaches earth, 170,000

years after is parent star exploded. Underground sensors years after is parent star exploded. Underground sensors in the United States and Japan first detect a wave of in the United States and Japan first detect a wave of subatomic particles known as neutrinos from the subatomic particles known as neutrinos from the explosion. Astronomers rush to telescopes in the explosion. Astronomers rush to telescopes in the southern hemisphere to study the progress of the southern hemisphere to study the progress of the explosion and perfect models describing the violent explosion and perfect models describing the violent deaths of large stars. deaths of large stars.

1990 Hubble launched1990 Hubble launched– The twelve-ton telescope, equipped with a 94-inch mirror, is The twelve-ton telescope, equipped with a 94-inch mirror, is

sent into orbit by astronauts aboard the space shuttle sent into orbit by astronauts aboard the space shuttle Discovery. Within two months, a flaw in its mirror is Discovery. Within two months, a flaw in its mirror is discovered, placing in jeopardy the largest investment ever in discovered, placing in jeopardy the largest investment ever in astronomy. astronomy.

1990 Big Bang confirmed1990 Big Bang confirmed– Astronomers use the new Cosmic Background Explorer Astronomers use the new Cosmic Background Explorer

satellite (COBE) to take a detailed spectrum of the satellite (COBE) to take a detailed spectrum of the microwave background radiation. These studies showed that microwave background radiation. These studies showed that the radiation is in nearly perfect agreement with the Big Bang the radiation is in nearly perfect agreement with the Big Bang theory. Two years later, scientists used the same instrument theory. Two years later, scientists used the same instrument to discover minute variations in the background radiation: the to discover minute variations in the background radiation: the earliest known evidence of structure in the universe.earliest known evidence of structure in the universe.

1993 Hubble optics repaired1993 Hubble optics repaired– Hubble's greatest legacy so far: detailed images of galaxies Hubble's greatest legacy so far: detailed images of galaxies

near the limits of the visible universe. near the limits of the visible universe.

FutureFuture 100 Trillion100 Trillion

– Astronomers assume that the universe will gradually wither Astronomers assume that the universe will gradually wither away, provided it keeps on expanding and does not recollapse away, provided it keeps on expanding and does not recollapse under the pull of its own gravity. During the Stelliferous Era, under the pull of its own gravity. During the Stelliferous Era, from 10,000 years to 100 trillion years after the Big Bang, most from 10,000 years to 100 trillion years after the Big Bang, most of the energy generated by the universe is in the form of stars of the energy generated by the universe is in the form of stars burning hydrogen and other elements in their cores. burning hydrogen and other elements in their cores.

10103737 yrs yrs– Most of the mass that we can currently see in the universe is Most of the mass that we can currently see in the universe is

locked up in degenerate stars, those that have blown up and locked up in degenerate stars, those that have blown up and collapsed into black holes and neutron stars, or have withered collapsed into black holes and neutron stars, or have withered into white dwarfs. Energy in this era is generated through into white dwarfs. Energy in this era is generated through proton decay and particle annihilation.proton decay and particle annihilation.

10103838 to 10 to 10100100 The Black Hole Era The Black Hole Era– After the epoch of proton decay, the only stellar-like

objects remaining are black holes of widely disparate masses, which are actively evaporating during this era.

1010100100 Dark Era Begins Dark Era Begins– At this late time, protons have decayed and black holes At this late time, protons have decayed and black holes

have evaporated.Only the waste products from these have evaporated.Only the waste products from these processes remain: mostly photons of colossal processes remain: mostly photons of colossal wavelength, neutrinos, electrons, and positrons. For all wavelength, neutrinos, electrons, and positrons. For all intents and purposes, the universe as we know it has intents and purposes, the universe as we know it has dissipated.dissipated.

From: PBS Online From: PBS Online (http://www.pbs.org/deepspace/timeline/)(http://www.pbs.org/deepspace/timeline/)

Aging the Earth & Solar SystemAging the Earth & Solar System

Dating meteorites, chunks of rock and metal, Dating meteorites, chunks of rock and metal, formed about the same time as the sun and formed about the same time as the sun and planets and from the same cloud.planets and from the same cloud.– Carbonaceous chondrites are a class of meteorites Carbonaceous chondrites are a class of meteorites

believed to be the most primitive in the solar system believed to be the most primitive in the solar system (silicate minerals, water and carbon)(silicate minerals, water and carbon)

Dating moon rocks and oldest rocks found on Dating moon rocks and oldest rocks found on Earth (about 3.8 BY old)Earth (about 3.8 BY old)

Rate of expansion (2002, astronomers had very Rate of expansion (2002, astronomers had very accurate measurements and calculated accurate measurements and calculated backwards to an age of 13-14 BY old).backwards to an age of 13-14 BY old).

How do we age things?How do we age things?

Isotopic decayIsotopic decay Radioisotopes are unstable and decay to form Radioisotopes are unstable and decay to form

daughter products which form next to parent daughter products which form next to parent nuclide.nuclide.

Know the ratio of daughter to parent in Know the ratio of daughter to parent in undisturbed sample and the rate of conversion undisturbed sample and the rate of conversion (e.g., decay rate or half-life) allows computation of (e.g., decay rate or half-life) allows computation of ageage

This has been done with several isotope pairs to This has been done with several isotope pairs to arrive at age of solar systemarrive at age of solar system

IsotopesIsotopes

The ordinary isotope of hydrogen, H, is known as Protium, the other The ordinary isotope of hydrogen, H, is known as Protium, the other two isotopes are Deuterium (a proton and a neutron; stable) and two isotopes are Deuterium (a proton and a neutron; stable) and Tritium (a protron and two neutrons; unstable). Hydrogen is the only Tritium (a protron and two neutrons; unstable). Hydrogen is the only element whose isotopes have been given different names. element whose isotopes have been given different names.

Radioactive decay – spontaneous disintegration of unstable nucleiRadioactive decay – spontaneous disintegration of unstable nuclei For low atomic number elements stable is about 1:1 neutrons:protons For low atomic number elements stable is about 1:1 neutrons:protons

in the nuclei. For higher atomic number elements, the ratio is about in the nuclei. For higher atomic number elements, the ratio is about 1.6:1.1.6:1.

Heavy nuclides (atomic number > 82) have no stable configuration.Heavy nuclides (atomic number > 82) have no stable configuration. Different types of decayDifferent types of decay FYI: FYI: Fusion of hydrogen into helium provides the energy of the Fusion of hydrogen into helium provides the energy of the

hydrogen bombhydrogen bomb

Some isotopesSome isotopesParent isotopeParent isotope Daughter IsotopeDaughter Isotope Half LifeHalf Life

238238UU 206206PbPb 4.47 x 104.47 x 1099 years years

235235UU 207207PbPb 7.04 x 107.04 x 1088 yrs yrs

232232ThTh 208208PbPb 1.40 x 101.40 x 101010 yrs yrs

8787RbRb 8787SrSr 4.88 x 104.88 x 101010 yrs yrs

4040KK 4040ArAr 1.25 x 101.25 x 1099 yrs yrs

3939ArAr 3939KK 269 yrs269 yrs

1414CC 1414NN 5,730 yrs5,730 yrs

147147SmSm 147147NdNd 1.06 x 101.06 x 101111 yrs yrs*daughters are smaller and contain fewer protons, neutrons & electrons

Doppler shiftingDoppler shifting

Wavelengths emitted by objects moving away are Wavelengths emitted by objects moving away are shifted to lower frequency (towards reds)shifted to lower frequency (towards reds)

Wavelengths emitted by objects moving towards Wavelengths emitted by objects moving towards us are shifted to higher frequency.us are shifted to higher frequency.

Example of sound – pitch of fire engine is higher Example of sound – pitch of fire engine is higher as truck moves towards you and lower as it moves as truck moves towards you and lower as it moves away)away)

For galaxies outside our group, the redshift is For galaxies outside our group, the redshift is known as hubble expansion (after Edwin Hubble known as hubble expansion (after Edwin Hubble who discovered this phenomenon in 1929).who discovered this phenomenon in 1929).

Another way to look at timeAnother way to look at time 0-7 No record (no baby pics)0-7 No record (no baby pics) 8-12 First rocks formed that are preserved today8-12 First rocks formed that are preserved today 1212 First living cell appearedFirst living cell appeared 22-23 Oxygen appeared22-23 Oxygen appeared 31 Atmosphere becomes oxygenated31 Atmosphere becomes oxygenated 40 First fossils formed (earlier records are dubious)40 First fossils formed (earlier records are dubious) 41 First vertebrates41 First vertebrates 41.7 First land plants41.7 First land plants 43 First reptiles43 First reptiles 4545 First flowering plants First flowering plants 45.6 Mammals, birds, insects became dominant45.6 Mammals, birds, insects became dominant 25 days ago25 days ago First human ancestorsFirst human ancestors 0.5 hours ago Civilization began0.5 hours ago Civilization began 1 min ago Industrial revolution began1 min ago Industrial revolution began

Geologic Time – Appendix IIGeologic Time – Appendix II

Emerging fieldEmerging field ExobiologyExobiology

– Carbonaceous chondritesCarbonaceous chondrites– Primordial soupPrimordial soup

– Reducing environmentsReducing environments– polymerizationpolymerization

Composition of a cellComposition of a cell– 59% H59% H– 24% O24% O– 11% C11% C– 4% N4% N– 2% Others (P, S, etc)2% Others (P, S, etc)

Composition of a cellComposition of a cell– 50% protein50% protein– 15% nucleic acid15% nucleic acid– 15% carbohydrates15% carbohydrates– 10% lipids10% lipids– 10% other10% other

Take home pointsTake home points Earth is ~4.5 BY oldEarth is ~4.5 BY old Big bang – expansion and formation of stars/planets from nebulaeBig bang – expansion and formation of stars/planets from nebulae How starts and planets form – condensation theoryHow starts and planets form – condensation theory Origin and formation of atomsOrigin and formation of atoms Changes in the early atmosphere – how it formed, how it changed Changes in the early atmosphere – how it formed, how it changed

and main causes for that changeand main causes for that change Oxygen in the atmosphereOxygen in the atmosphere Origin of water (planetary outgassing, comets, meteorites)Origin of water (planetary outgassing, comets, meteorites) Sources of heat in the early earth – is the earth heating or cooling?Sources of heat in the early earth – is the earth heating or cooling? Dating the earth – how do we do it? What do we date?Dating the earth – how do we do it? What do we date? Early ocean acidic because of high concentration of carbon dioxideEarly ocean acidic because of high concentration of carbon dioxide

Take home (cont)Take home (cont)

Life originated ~ 3.8 BY agoLife originated ~ 3.8 BY ago– Sources of building blocks and energy for lifeSources of building blocks and energy for life– Early environmentsEarly environments

Where is the water on earth (reservoirs)Where is the water on earth (reservoirs) Building blocks for life – where do the C compounds and Building blocks for life – where do the C compounds and

energy come fromenergy come from Miller-Urey experiments (synthesis of organic compounds Miller-Urey experiments (synthesis of organic compounds

from chemical soup and energy)from chemical soup and energy)