Download Dwarf Planet

Earth’s Origin
and
Planetary Geology
I. The Sun
A. The Sun is a _____.
star
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.
B. Size of the Sun
If the Sun was a
Volley ball . . .
• Jupiter would be
roughly the size
of a nickel.
• Earth would be
about the size of
a pinhead
109 times Earth’s diameter (1.38 x 106 km)
1. Size: _______
1,300,000
2. Volume: Could hold more than ________
Earth’s.
3. Mass
• 745 times greater than the combined mass of all the
planets in the Solar System
C. The Source of the Sun’s Energy
Fusion light elements into heavier
1. ________of
elements by high temperature and
pressure in the core.
2. 75% of the Sun’s mass is hydrogen
Hydrogen atoms fuse, producing
3. _________
energy
_________
and _________.
Helium
Fusion 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 Stars
II. Distances in Space
A. _________________
Astronomical Unit
1. Distance measured
Sun
to the ________
, the
closest star to Earth
2. 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.
The Light Year
B. __________________
No . . .
Not this guy (Buzz Lightyear of Toy Story)
Light 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
490 LY from Earth.
Orion the Hunter
III. Theories on the Origin of the Universe
and the Solar System
Bang
A. The Big
________
No, not these guys…
A. The Big
________
Bang
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.
What is meant by an expanding
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 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 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 Bang
9.1 billion years
B. Galaxies
Top View
1.
2.
3.
Side View
4.
A galaxy is a system
containing
___________
billions of stars.
Space contains several
billion galaxies
____________
Peak of galaxy
formation occurred
when the universe was
about three billion years
old.
Galaxies glow from the
combined light of
billions of stars.
Types of Galaxies
Peculiar GalaxiesAbnormal in size and shape
Barred Spiral
Galaxy
Elliptical
Galaxy
Irregular Galaxies –
The Magellanic Clouds
The Milky Way
5. ______________
a. The Home Galaxy to which the Sun belongs
b. A spiral galaxy
c. Diameter: 140,000 light
years
d. 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
_____________
Local Group
140,000 LY
C.
Origin of the Solar System (____________
Solar Nebula Theory)
1.
Planets formed at the
___________
as the
same time
Sun and from the
same nebular
material.
a. The Sun, Earth and the
Moon are all about
4.6 billion yrs old
_________________.
b. Mercury, our Moon, and the moons of the outer planets
craters
are scarred with __________.
c. This suggests they were bombarded with objects in the
past.
Jupiter’s Moon Io
Jupiter’s Callisto
• The most cratered object in the Solar System
The 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 System
Solar 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 Theory
•
The rotation of
the cloud
caused it to
flatten.
–
–
Formed a
rotating disk.
The bulge in
the center
became the
Sun.
Accretion
• 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 Sun
•
•
Too warm for water-ice to condense
Solid particles were silicate and iron-rich matter.
Outer Part of Disk
(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 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 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) 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 Earthsized rocky bodies (original materials of the planets)
Called gas giants because of huge gaseous atmospheres.
Our 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 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 Ellipse
Circle
• 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
Eccentricity of an Ellipse
Circle
• 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
Earth’s Elliptical Orbit
• Earth’s orbit is a nearly circular ellipse
Earth’s Elliptical Orbit
• Earth’s orbit is a nearly circular ellipse
Earth’s Elliptical Orbit
• Earth’s orbit is a nearly circular ellipse
Earth’s Elliptical Orbit
• Earth’s orbit is a nearly circular ellipse
Earth’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 Configuration
X
Solar System Configuration
Pluto is no longer considered a planet!
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 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
Planets
4. Terrestrial
________________
a. Closer to the Sun and most
lighter elements driven off.
b. Small, rocky, and dense
c. Mercury, Venus, Earth, Mars
d. No atmosphere. (Originally)
e. Numerous impacts of objects
from space (meteors, comets)
Earth’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 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 Layers
• Lithosphere
– solid upper
mantle and crust
– broken into
plates that
move over the
asthenosphere
• Asthenosphere
– part of upper
mantle
– behaves
plastically and
slowly flows
Hot, Barren, Waterless Early Earth
• about 4.6 billion years ago
• 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
f. Origin of Earth’s Atmosphere
Volcanic Outgassing
1. ________________________:
Atmosphere
evolved from the release of water from volcanoes.
2. Earth’s Primordial Atmosphere
• Earth’s very early atmosphere was probably composed of
hydrogen
helium
___________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
Outgassing
• 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
g. ___________
Meteorites
• Some meteorites contain water which likely was
released into the impact when the vaporized upon
impact with Earth’s surface.
Comets
• 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)
Hydrogen
Deuterium
• Earth’s oceans contain HDO
• Comet impacts might have contributed significant water
to the formation of Earth’s atmosphere and the oceans.
h. Origin of Earth’s Oceans:
Release of water from precipitation over millions
of years early in Earth history.
Forming 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 Belt
Asteroids
Asteroid Impacts
Asteroid Impacts
Meteorite Impact
Barringer 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”
• Width: 1 mi (1.2 km)
• Depth: 570 ft (175 m)
Chicxulub – An Extinction Event
Gas Giants
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.
Jupiter
At last count, Jupiter has 63 moons.
Jupiter’s Moon Europa
Saturn
Saturn’s Structure
Saturn’s Moons
• At last count, Saturn has 60 confirmed natural
satellites.
Uranus – The “U” Planet
Neptune
The 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 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 Planet
Sedna
Sedna and its moon
Sedna’s Location
Trans-Neptunian Object 2003UB313 (“Xena”)
III. Earth’s Age
A. Oldest Earth Materials
rock found on Earth on Earth (as of 2002)
1. Oldest _________________
a. 4.03 billion years old
b. From northwestern Canada
2. Oldest known _________________
(found in 2001)
detrital mineral
a. Zircon crystal from Australia
b. 4.4 billion years old
B. Estimates of Earth’s Age
Allende CV3 meteorite
4.56 x 106 yrs
1.
2.
3.
4.
4.6 billion years
Based on isotopic dating of _____________and
_________________.
meteorites
Moon rocks
According to current theories on formation of the Solar System, the sun,
at the same time
planets, and other objects in the Solar System formed _______________.
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 ______________________.
at the same time