Earth’s Origin Earth’s Origin and and

Planetary GeologyPlanetary Geology

I. The SunI. The SunA. The Sun is a _____.

1. A hot gaseous sphere • with a surface temperature of about 5,550o Celsius (approximately

10,000o Fahrenheit) • Interior temperature may be as high as 15,000,000o Celsius

2. Radiates energy into space.

star

B. Size of the SunB. Size of the Sun

1. Size: _______ times Earth’s diameter (1.38 x 106 km)

2. Volume: Could hold more than ________ Earth’s.

1091,300,000

If the Sun was aVolley ball . . .

• Jupiter would be roughly the size of a nickel.

• Earth would be about the size of a pinhead

3. Mass3. Mass

• 745 times greater than the combined mass of all the planets in the Solar System

C. The Source of the Sun’s EnergyC. The Source of the Sun’s Energy

1. ________of light elements into heavier elements by high temperature and pressure in the core.

2. 75% of the Sun’s mass is hydrogen

3. _________ atoms fuse, producing _________ and _________.

Fusion

                          

HydrogenHelium energy

Fusion in the SunFusion in the Sun• Deuterium (2H) and Tritium

(3H) have formed from the collision of protons. – These are isotopes of

hydrogen. – They have extra neutrons in

the nucleus. • The deuterium and tritium

combine to form helium. • The mass of the helium that is

formed and the emitted particle is less than the mass of the hydrogen that started the process.

• The missing mass has been converted to energy and released.

• Estimates indicate that about 4 million metric tons of matter are converted into energy every second.

• But because the Sun is so massive, this process can continue for another five billion years!

Comparing the Sizes of StarsComparing the Sizes of Stars

II. Distances in SpaceII. Distances in Space

A. _________________1. Distance measured to the ________ , the closest star to Earth2. Equal to the average distance between the Sun and Earth (150,000,000 km or 93,000,000 mi.)3. Used for distances within our Solar System.

Sun

Astronomical Unit

B. __________________B. __________________

No . . .

Not this guy (Buzz Lightyear of Toy Story)

The Light YearThe Light Year

Light YearLight Year

1. The distance that a ray of light travels in one year

2. At the speed of light (300,000 km/sec or 186,000 km/sec) light travels about 9.4 trillion kilometers (5.8 trillion miles) in one year

3. Double stars of Alpha Centuri are about 4.3 LY from Earth.

4. The red giant star Betelgeuse is nearly 4. The red giant star Betelgeuse is nearly 490 LY from Earth.490 LY from Earth.

Orion the HunterOrion the Hunter

III. Theories on the Origin III. Theories on the Origin of the Universe and the of the Universe and the

Solar SystemSolar System

A. The ________A. The ________Big BangBig Bang

No, not these guys…No, not these guys…

A. The ________A. The ________1. The entire universe was a

very hot dot, smaller than the diameter of an atom

2.  13.7 billion years old Based on recent research with only

a 1% margin error.)a.  Expanded

faster than the speed of light

b.  Mechanism that initiated the event is still being

researched.

Big BangBig Bang

What is meant by an expanding What is meant by an expanding universe?universe?

• According to the Big Bang model, the point of energy exploded in an incredibly giant and violent event.

• It wasn’t like a bomb exploding. – When a bomb explodes fragments are sent outward

in all directions.

• The Big Bang caused space itself to expand. – As space expanded, particles formed and were

carried away from each other.

Model of an Expanding UniverseModel of an Expanding Universe

• Imagine the universe as being curved like a balloon.– Galaxies are drawn on the balloon. These represent galaxies.

• As the balloon is inflated space between the dots increases. • When seen from any galaxy, the other galaxies are moving away

The Big BangThe Big Bang• Cooling eventually

resulted in the formation of hydrogen, helium, deuterium and lithium atoms

• Stars were born at +200 million years

• Peak of galaxy formation at + 3 billion years

Simplified Timeline of Events after the Big BangSimplified Timeline of Events after the Big Bang

9.1 billion years

B. B. GalaxiesGalaxies

1. A galaxy is a system containing___________ of stars.

2. Space contains several ____________ galaxies

3. Peak of galaxy formation occurred when the universe was about three billion years old.

4. Galaxies glow from the combined light of billions of stars.

billions

billion

Top View

Side View

Types of GalaxiesTypes of Galaxies

Irregular Galaxies –The Magellanic Clouds

EllipticalGalaxy

Barred SpiralGalaxy

Peculiar Galaxies- Abnormal in size and shape

5. ______________5. ______________a. The Home Galaxy to which the Sun belongsa. The Home Galaxy to which the Sun belongs

b. A spiral galaxyc. Diameter: 140,000 light

yearsd. Greatest thickness:

20,000 light years.e. Sun: About 23,000 light

years from the galaxy’s center.

f. Approximately 100 billion stars.

g. Belongs to a small cluster of 40 galaxies know as the _____________

The Milky WayThe Milky Way

140,000 LY

Local Group

C.C. Origin of the Solar System (____________ Theory)Origin of the Solar System (____________ Theory)

1. Planets formed at the ___________ as the Sun and from the same nebular material.

a. The Sun, Earth and the Moon are all about

_________________.

Solar NebulaSolar Nebula

same time

4.6 billion yrs old

b. Mercury, our Moon, and the moons of the outer planets are scarred with __________.

c. This suggests they were bombarded with objects in the past.

craters

Jupiter’s Moon IoJupiter’s Moon Io

Jupiter’s CallistoJupiter’s Callisto

• The most cratered object in the Solar System

The Solar NebulaThe Solar Nebula• Solar system born 4.6 billion

years ago• A few light-years in diameter• Composed mostly of gaseous

– Hydrogen (71%)– Helium (27%)– Traces of other gases

• Microscopic dust– Mixture of silicates, iron compounds, carbon compounds and water ice

• Collapse may have been triggered by a nearby exploding star or a collision with another cloud

Formation of the Solar SystemFormation of the Solar System

Solar Nebula TheorySolar Nebula Theory

• Gravitational attraction between the particles in the interstellar gas cloud (nebula) cause it to collapse inward.

• Could have been caused by:

– Nearby exploding star– Collision with another

cloud.

Solar Nebula TheorySolar Nebula Theory

• The rotation of the cloud caused it to flatten.

– Formed a rotating disk.

– The bulge in the center became the Sun.

AccretionAccretion

• Particles in the disk began to stick together, possible assisted by static electric forces.– The particles grew in size as the combined (a

process called “accretion.”)– Composition of particles depended on where they

were in the disk.

Inner Part Near the SunInner Part Near the Sun

• Too warm for water-ice to condense• Solid particles were silicate and iron-rich matter.

Outer Part of DiskOuter Part of Disk (at about the distance of Jupiter from the Sun)(at about the distance of Jupiter from the Sun)

• Cold enough for water-ice to form• Particles silicate and iron-rich material and frozen water.• These particles grew much larger than the particles in the inner part of the

cloud.

Planetismals FormedPlanetismals Formed

• If collisions between particles were not too violent they stuck together.

• Smaller particles gradually grew until they were several kilometers wide.

• These small, planet-like bodies are called planetesmals.

Formation of PlanetsFormation of Planets

• Planetesmals began to collide and grow (accretion)

– If they were not completed destroyed, they merged.

– Their orbits became nearly circular.

• Mass increased due to accretion.

Outer (Jovian) PlanetsOuter (Jovian) Planets

• Grew larger – Water-ice could form– Water-ice was about 10 times more abundant than silicon and

iron-rich compounds.– With larger mass, these planets could attract more material.

• Gas could be attracted and retained due to the large gravity.– Extremely large hydrogen-rich atmospheres surround Earth-

sized rocky bodies (original materials of the planets)– Called gas giants because of huge gaseous atmospheres.

Our Solar SystemOur Solar System

• 8 planets• 172 known moons (satellites) as of October 2008• a tremendous number of asteroids

– most orbit the Sun between the orbits of Mars and Jupiter• Millions of comets and meteorites• Interplanetary dust and gases

Elliptical OrbitsElliptical Orbits

• The shape the orbits of all planets are ellipses• Ellipses have two focal points, unlike the circle

which has one central focus– The Sun is located at one focus and the other is

empty

Eccentricity of an EllipseEccentricity of an Ellipse

• The degree of departure from a perfectly circular orbit.• Related to the lengths of the:

– Major Axis: Longest axis through the foci– Minor Axis: Shorter axis

Circle

Eccentricity of an EllipseEccentricity of an Ellipse

• Eccentricity increases as the lengths of the two axes become more unequal.– At extreme eccentricity the two axes are equal– A circular orbit has no eccentricity

Circle

Earth’s Elliptical OrbitEarth’s Elliptical Orbit

• Earth’s orbit is a nearly circular ellipse

Earth’s Elliptical OrbitEarth’s Elliptical Orbit

• Earth’s orbit is a nearly circular ellipse

Earth’s Elliptical OrbitEarth’s Elliptical Orbit

• Earth’s orbit is a nearly circular ellipse

Earth’s Elliptical OrbitEarth’s Elliptical Orbit

• Earth’s orbit is a nearly circular ellipse

Earth’s Elliptical OrbitEarth’s Elliptical Orbit

• The effect of Earth’s elliptical orbit on season is very small, varying by only a few percentage points

• The longer period (7 days) between the March Equinox and the September equinox tends to compensate.

Solar System ConfigurationSolar System Configuration

X

Solar System ConfigurationSolar System Configuration

Pluto is no longer considered a planet!

Pluto’s Been Demoted!Pluto’s Been Demoted!

• On August 24, 2006 the International Astronomical Union redefined the definition of a planet as:– “a celestial body that is in orbit around the sun– has sufficient mass for its self-gravity to

overcome rigid body forces so that it assumes a nearly round shape,

– and has cleared the neighborhood around its orbit.”

Pluto is now considered a “Dwarf Planet”Pluto is now considered a “Dwarf Planet”

• Pluto lost its status as a planet because it’s highly eccentric orbit crosses over the orbit of Neptune.– As such it hasn’t “cleared the

neighborhood around its orbit.

• A dwarf planet like Pluto is– Any other round object that

• Has not “cleared the neighborhood around its orbit• Is not a satellite

4. ________________4. ________________

a. Closer to the Sun and most lighter elements driven off.

b. Small, rocky, and densec. Mercury, Venus, Earth, Marsd. No atmosphere. (Originally)e. Numerous impacts of objects

from space (meteors, comets)

Terrestrial PlanetsTerrestrial Planets

Earth’s DifferentiationEarth’s Differentiation

• Differentiation = segregated into layers of differing composition and density

• Early Earth was probably uniform

• Molten iron and nickel sank to form the core

• Lighter silicates flowed up to form mantle and crust

Earth’s Interior LayersEarth’s Interior Layers

• Crust - 5-90 km thick– continental and

oceanic

• Mantle– composed largely of

peridotite– dark, dense

igneous rock – rich in iron and

magnesium

• Core– iron and a small

amount of nickel

Earth’s Interior LayersEarth’s Interior Layers

• Lithosphere– solid upper

mantle and crust

• Asthenosphere– part of upper

mantle– behaves plastically

and slowly flows

– broken into plates that move over the asthenosphere

• Shortly after accretion, Earth was – a rapidly rotating, hot, barren, waterless planet– bombarded by comets and meteorites– with no continents, intense cosmic radiation – and widespread volcanism

Hot, Barren, Waterless Early EarthHot, Barren, Waterless Early Earth

• about 4.6 billion years ago

                                

1. ________________________: Atmosphere evolved from the release of water from volcanoes.

 

Volcanic Outgassing

f. Origin of Earth’s Atmospheref. Origin of Earth’s Atmosphere

• Earth’s very early atmosphere was probably composed of ___________and _________,

• the most abundant gases in the universe• If so, it would have quickly been lost into space

– because Earth’s gravity is insufficient to retain them– because Earth had no magnetic field until its core

formed• Without a magnetic field,

– the solar wind would have swept away any atmospheric gases

2. Earth’s Primordial Atmosphere2. Earth’s Primordial Atmosphere

hydrogen helium

• Once a core-generated magnetic field – protected the gases

released during volcanism• called outgassing

– they began to accumulate to form a new atmosphere

• Water vapor – is the most common

volcanic gas today– but volcanoes also emit – carbon dioxide, sulfur

dioxide,– carbon monoxide, sulfur,

hydrogen, chlorine, and nitrogen

OutgassingOutgassing

g. ___________g. ___________

• Some meteorites contain water which likely was released into the impact when the vaporized upon impact with Earth’s surface.

MeteoritesMeteorites

CometsComets

• A new class of comets, “main belt comets” may have formed within the orbit of Jupiter– Contain “Heavy” water (HDO) which has equal parts Hydrogen,

Oxygen, and Deuterium (an isotope of H with extra neutron)

• Earth’s oceans contain HDO• Comet impacts might have contributed significant water

to the formation of Earth’s atmosphere and the oceans.

Hydrogen Deuterium

h.  Origin of Earth’s Oceans:h.  Origin of Earth’s Oceans:

Release of water from precipitation over millions of years early in Earth history.

Forming the Earth - Moon SystemForming the Earth - Moon System• Impact by Mars-sized or larger planetesimal

with young Earth– 4.6 to 4.4 billion

years ago

– Ejected a large quantity of hot material,

– and formed the Moon

The Asteroid BeltThe Asteroid Belt

AsteroidsAsteroids

Asteroid ImpactsAsteroid Impacts

Asteroid ImpactsAsteroid Impacts

Meteorite ImpactMeteorite Impact

Barringer Crater, AZBarringer Crater, AZ

• Width: 1 mi (1.2 km)• Depth: 570 ft (175 m)• Created by the impact of a 50 m wide iron meteor 50,000 yrs. ago

Also Known as “Meteor Crater”Also Known as “Meteor Crater”

• Width: 1 mi (1.2 km)• Depth: 570 ft (175 m)

Chicxulub – An Extinction EventChicxulub – An Extinction Event

j. ____________j. ____________

• Larger mass– Able to attract and retain gas by their own gravity– Most likely slightly larger than Earth-sized bodies of ice and rock

surrounded by huge hydrogen-rich atmospheres.

Gas Giants

JupiterJupiter

At last count, Jupiter has 63 moons.

Jupiter’s Moon EuropaJupiter’s Moon Europa

SaturnSaturn

Saturn’s StructureSaturn’s Structure

Saturn’s MoonsSaturn’s Moons

• At last count, Saturn has 60 confirmed natural satellites.

Uranus – The “U” PlanetUranus – The “U” Planet

NeptuneNeptune

The Kuiper Belt and Oort CloudThe Kuiper Belt and Oort Cloud

• Kuiper (pronounced “Ki-Per”) Belt objects are believed to be the remnants of the Solar System’s early accretional phase. Objects between 30 AU and 50 AU include

– dwarf planets (Trans-Neptunian Objects) – Short period comets

The Oort CloudThe Oort Cloud

• The Oort cloud contains long-period comets, most likely a result of the sling-shot effect of the gas giant planets

Pluto, The Dwarf PlanetPluto, The Dwarf Planet

SednaSedna

Sedna and its moon

Sedna’s Location

Trans-Neptunian Object 2003UBTrans-Neptunian Object 2003UB313313 (“Xena”) (“Xena”)

III. Earth’s AgeIII. Earth’s Age

A. Oldest Earth Materials1. Oldest _________________ on Earth (as of 2002)

a. 4.03 billion years old

b. From northwestern Canada

2. Oldest known _________________ (found in 2001)a. Zircon crystal from Australia

b. 4.4 billion years old

detrital mineral

rock found on Earth

B. Estimates of Earth’s AgeB. Estimates of Earth’s Age

1. 4.6 billion years2. Based on isotopic dating of _____________and _________________.3. According to current theories on formation of the Solar System, the sun,

planets, and other objects in the Solar System formed _______________.4. Even though no rocks as old as Earth have been found, the age has been

inferred from dating meteorites and Moon rocks because it’s probable that they and Earth formed ______________________.

Allende CV3 meteorite4.56 x 106 yrs

meteorites Moon rocks

at the same time

at the same time