Cosmic - Science A 2 Z

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Transcript Cosmic - Science A 2 Z

Cosmic Influences
On Earth
Big Bang
• Estimated to have
occurred 13.7 ± 0.13
billion years
– WMAP (Wilkinson
Microwave Anisotrophy
(variation in
temperature) Probe
– Mapping Universe
• Big Bang – 3.47min
Concepts in Cosmology
• Big Bang Theory:
– Leads to a point of common
origin for all matter
– This point of common origin is
where everything came into
being in a single instant
– Because time and space
originated in the Big Bang,
it did not occur in any
specific location of space
– Every point in the universe
was there when the Big
Bang occurred, and
therefore, every point in the
universe is where the Big
Bang happened
– The cosmic microwave
background radiation is the
echo of the Big Bang.
Concepts in Cosmology
• Big Bang Theory: (cont)
– As the universe expanded, the
wave stretched-out, much like
a phone cord is stretched as
you walk away from the base
– The stretched-out wave would
be very long and have very low
– Two scientists, A. Penzias and
R. Wilson, discovered this
radiation, experimental
verification of the Big Bang.
2 billion years after the big bang
Concepts in Cosmology
• Future of the Universe
– Big Crunch: If universe is
greater than the critical density,
collective gravity of all the
matter in the universe will stop
expanding and begin to
– Expanding Universe: If
universe less than the critical
density (current scientific
theory), then universe will
expand forever.
• Our universe is
estimated to have 125
– 500 billion galaxies
• The average number
of stars per galaxy is
given as 200 billion
• Error???
• Big 2.10 min
Two Inch Universe
• If the Solar System is
shrunk to 2 inches in
diameter, then
– The nearest star is 2
football fields away
– The nearest star known
to have planets is 6
football fields away
– The Milky Way galaxy
is the size of North
Milky Way
• Starting with ours –
the Milky Way
• In a plane, the center
found in the
Sagittarius Arm
• Silly name???
– Nyx, goddess of the
night sky, dripped milk
• SS in MW
Our Solar System
• Medium size sun
• 8 planets
4 rocky inner planets
4 gas giants
5 dwarf planets
Asteroid Belt between last
rocky and first gas giant
– Kuiper Belt, of which Pluto
is a large member
– Oort Cloud
Theories of Life
• SETI (Search for Extra-Terrestrial Intelligence)
– Life, including intelligent
life, is found everywhere in
our galaxy as well as other
• Rare Earth Hypothesis
– Most solar systems not
suitable for life, but only in
narrow habitable zones
Drake’s Equation
• R* = 10/year (10 stars
formed per year, on the
average over the life of the
• fp = 0.5 (half of all stars
formed will have planets)
• ne = 2 (stars with planets
will have 2 planets
capable of supporting life)
• fl = 1 (100% of these
planets will develop life)
• fi = 0.01 (1% of which will
be intelligent life)
• fc = 0.01 (1% of which
will be able to
• L = 10,000 years (which
will last 10,000 years)
• N = 10 × 0.5 × 2 × 1 ×
0.01 × 0.01 × 10,000 = 10,
or the number of advanced
Drake’s Equation
• Huge assumptions –
which will greatly
change the estimated
number of intelligent
civilizations in a
• Range from 2.31 to
Habitable Zone
• Where do we look?
– Not too hot
– Not too cold
– Just right
Habitable Zones
• Greatest diversity and
density of life found
on our planet as we
approach the equator
Habitable Zones
• Only life known is
– Possible Mars
– Possible satellites
around Jupiter or
• However, are those too
• Possible when sun
Habitable Zones
• Not only on Earth and
in our solar system,
but also in our galaxy
– Too close to the center
of the galaxy, too much
– Too far out on an arm,
not enough radiation
• The only confirmation of
life is on Earth
• Distance to the farthest
reaches of our observable
universe is 46.5 billion
light years
• Billions of galaxies with
billions of stars
• Far fetched to think we are
alone, but technologically
intelligent life?????
Back to Earth
• What cosmic
influences can impact
(literally) the Earth?
• Meteors
• Asteroids
• Comets
• Sun
• Moon
• Earth
Asteroid Belt
• Total mass smaller
than our moon (but
much of the mass lost)
• 26 large and millions
of small asteroids
• Ceres largest, now
classified as a minor
Oort Cloud
• Outer reaches of our
solar system from
Kuiper Belt to
• Billions of comets
• Medium yellow star
• ~10 billion life span
• Primarily hydrogen
with some helium
• Converts ~8 tons of
matter per second to
E = mc2
Size 1
Size 2
Energy Output
• Sun produces so much
energy, that one second is
equivalent to the the
current energy used by
world for 500,000 years
• Most of the energy is xray, ultraviolet, visible,
and infrared plus
subatomic and charged
• From Newton to
• Spacetime and Gravity
Earth in Space
• Earth protected by
magnetic fields
– Generated in outer
liquid iron/nickel core
• Earth protected by
– Screens gamma rays,
x-rays and most
ultraviolet rays
Energy to Earth
What day is this?
Spring Equinox
Summer Solstice
Fall Equinox
Winter Solstice
Seasons 5.53 min
Solar Incidence of Angle
• Light travels in a
straight line
• The curvature of the
Earth forms the
Incidence of Angle
• The same amount of
energy is spread over a
larger area
Solar Radiation
• Solar radiation
– X-ray – blocked by
– Ultraviolet – mostly
blocked by atmosphere
– Visible – permeates,
partially blocked by
– infrared – permeates
• Albedo is the fraction of solar
energy reflected from the Earth
back into space
– a measure of the reflectivity of
the earth's surface
• Light soils, heavily vegetated
areas have a high albedo
• Dark soils, open areas have a
low albedo
• Ice, especially with snow on
top of it, has a high albedo
• Water is much more
absorbent and less reflective,
and has a low albedo
Human Activity
• All organisms change
their environment –
not just humans
• Impact relating to
lowering the albedo:
– Pollution on ice and
– Asphalt and cities
– Clear cut or slash and
Seasons and Sunlight
• What is the solar angle of
incidence for the equator for the
globe on the left?
A. 90°
B. 66.5°
C. 47°
D. 43°
• The globe on the left represents:
A. Summer Solstice
B. Winter Solstice
C. Equinox and cannot tell if
it is the spring or fall
Not enough information
Seasons and Sunlight
• What is the solar angle of
incidence for the equator for the
globe on the right?
A. 90°
B. 66.5°
C. 47°
D. 43°
• The globe on the right represents:
A. Summer Solstice
B. Winter Solstice
C. Equinox and cannot tell if
it is the spring or fall
Not enough information
Direction of Rotation
If you are looking
down at the North
Pole, does the earth
A. Counterclockwise
B. Clockwise
• 100,000 year cycle
• Winter in North at
Perihelion, and therefore
shorter than summer
• Low eccentricity of 0.005
• High eccentricity of 0.058
• Mean eccentricity of 0.028
• Present eccentricity 0.017
• Moving towards low
centricity - warming
Tilt of the Axis
41,000 year cycle
Minimum tilt is 21.1º
Maximum tilt is 24.5º
Currently at 23.5º
Tilt is decreasing cooling
• Wobble like a top
• Completes the wobble
every ~21,000 years
• Other “north stars,
Thuban in Draco and
Vega in Lyra
• Top 10 sec
• Both 33 sec
Milankovitch Cycles
• These three cycles, in
combination, can alter
– Eccentricity
– Obliquity
– Precession
• Milankovitch 2.38 min