Transcript Introduction to the Earth

The Rest of the Universe
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Chapter 9 CPO Science
Where are you?
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The Earth circles the sun
The sun is one of billions of billions of stars.
To measure distances between stars we a
distance measurement called the Light- year
1 light-year is the distance light travels in one
year.
Since light travels at 186,000 miles per second,
A light year is approximately 6 trillion miles
Andromeda
The Cosmic Zoo
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Stars
Planets
Gas Nebulae
Star Clusters
Galaxies
Clusters of Galaxies
Large-scale
structures
Stars
Are formed by the same forces
 Have different
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Size
 Composition
 Temperature
 Color
 Mass
 Brightness
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Composition
Determined with a spectroscope
 by the colors of light it gives off
 The lightest element Hydrogen makes up
60 - 80 % of a star
 Helium is second most
 96-99 % is hydrogen and helium
 rest is other elements 
The Electromagnetic Spectrum
Chemistry from Spectra
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Emission Spectra
Chemistry from Spectra
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Absorption Spectra
Spectroscope
Breaks the light of a star up into its colors
 Called a spectrum
 Kind of spectrum tells scientists
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what the star is made of
 which way and how fast it is moving
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Analyzing Stellar Spectra
Anomalies in positions of absorption
bands
 Normal Spectrum
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• Spectra from stars will have lines
missing
Size
5 main categories
 Medium sized - like our sun
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from 1/10 size of sun to 10 times it’s size
Giant stars- 10 to 100 times bigger than
the sun
 Supergiant stars- 100 to 1000 times bigger
than the sun
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The Red Giant
Size
White dwarfs- smaller than 1/10 the size of
the sun
 Neutron stars - smallest stars - about 16
km in diameter
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Temperature
Blue
Color also
indicates
temperature
White
 hottest surface
50000 °C
Yellow
 coolest -3000°C
Red-orange
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Red
35,000 °C
10,000 °C
6,000 °C
5,000 °C
3,000 °C
Brightness
Magnitude - measure of brightness
 Apparent magnitude - how bright it looks
from earth
 Absolute magnitude - how bright it really is
 Variable stars - brightness changes from
time to time
 Cephid variables - pulsating variableschange both brightness and size
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Hertzsprung-Russell diagram
Found that as temperature increased, so
did absolute magnitude
 90% of stars followed this pattern
 Called main sequence stars
 Other 10% were once main sequence
stars but have changed over time
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Absolute Magnitude
Supergiants
50000
Giants
20000
10000 6600
6000
5000
3000
Star Life Cycles
Stars change over time
 New stars form from nebulae
 Gravity pulls the dust and gas together
 Mostly hydrogen
 Forms a spinning cloud
 Hydrogen atoms hit each other and heat
up
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Star Life Cycle
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When the temperature reaches
15,000,000 °C fusion begins
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Makes a protostar - a new star
What determines the life cycle of the star is
how much mass it starts with.
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Star Birth
The Solar System - Its Origin
and Early Development
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Our solar system,
part of the Milky
Way galaxy,
consists of the Sun,
nine planets, 64
known moons,
many asteroids,
millions of comets
and meteorites, as
well as
interplanetary dust
and gases
Neutron Stars
If the star started out 6 to 30 times the
mass of the sun, the core of the exploding
star becomes a neutron star.
 As massive as the sun, but only 16 km
across.
 Neutron stars spin rapidly and give off
pulses of radio waves
 If these radio waves come in pulses it is
called a pulsar
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Black holes
If the star was bigger than 30 times the
mass of the sun
 The left over core becomes so dense that
light can’t escape its gravity.
 Becomes a black hole.
 Grab any nearby matter and get bigger
 As matter falls in, it gives off x-rays.
 That’s how they find them
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How far are the stars? How big
is the Universe?
We can measure distances to stars by two
methods
 One method – parallax is only good for the
very nearest stars
 The other method – comparison of
magnitudes is more complex, but it can be
used for even the farthest stars and
galaxies.
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Measure the angle to the star
Wait half a year
Measure the angle to the star
Triangle tells distance
Distance to stars
Parallax works only to 100 light-years
 More than 100 light-years they use a
complicated formula based on apparent
and absolute magnitude.
 More than 7 million light-years they use
the red shift
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Doppler Effect
Change in wavelength
caused by the apparent
motion of the source.
 Cars moving by you
 Same things happen to
light
 Light from objects coming
toward you is compressed
looks more blue
 Light from objects away
looks more red
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Using the Doppler Effect to Measure Velocity
Blueshift
Redshift
Animation
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http://lectureonline.cl.msu.edu/~mmp/appli
st/doppler/d.htm
Edwin Hubble at Mt. Wilson
Hubble’s observations at the 100 inch during the
1920’s led him to the conclusion that the universe
is expanding, and that an object’s recession velocity
is proportional to its distance from the observer.
Hubble guiding the Hooker
100 inch telescope in 1923.
The Hooker 100 inch telescope atop Mt. Wilson
near Pasadena, CA. It was the largest telescope in
the world from 1917-1947.
Deep Hubble Space Telescope Image
A deep image of an “empty”
portion of the sky with the
Hubble Space Telescope
reveals that the universe is
filled with galaxies- many just
like our own. The light
we see from the most distant
galaxies has traveled approximately 10 billion years to
reach us.
Hubble’s Law
Nearly all galaxies in the Universe display
RED SHIFT
 The amount of RED SHIFT is related to
the relative distance to the galaxy.
 FARTHER galaxies show GREATER RED
SHIFT
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Example of Red Shift
Normal Spectrum
Shifted Spectrum
Hubble’s Law – What does it
mean?
Is the Earth the center of the Universe
after all and everything is moving away
from us?
 Does it depend on frame of reference?
 Would Hubble’s Law apply if we looked at
the Universe from another location?
 Why is everything moving away?
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Hubble’s Observation/
Hubble’s Insight
All galaxies appear to be moving away
from the center of the Universe because
the Universe is expanding.
 The existence of RED SHIFT and the
pattern that it shows (greater shift for
farther galaxies) is consistent with a
pattern produced by an explosion –
 THE BIG BANG!!
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What was the Big Bang?
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Prior to the Big Bang – there was no Universe
A single super-massive object exploded
Explosion creates Universe
Matter, space and time are created
Explosion was approximately 15 billion years
ago
Currently the best theory to explain the origin of
the Universe
Supported by multiple lines of evidence
News Flash: NASA/CNN report first stars
formed early than once thought
Evidence in support of
Big Bang Theory
Hubble’s Law and pattern of red shift
 Cosmic Background Radiation
 Mathematical models
 Particle physics theory
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Cosmic Microwave Background
Arno Penzias and Robert Wilson were trying to make observations of radio
emissions from a distant supernova and then hoped to make a map of
radio emissions from the Milky Way. They adapted a radio dish previously
used for communication satellites. They were startled to find that no
matter where they pointed the antenna, they measured the same low-level
radio signal. After great efforts to determine that there was nothing wrong
with the antenna, they concluded that the signals were real and a property
of the universe.
Penzias and Wilson, 1965
Arecibo Dish, Puerto Rico
New Insights into the Big Bang
Recent mapping of microwave and
temperature variations suggest that the
Universe may be flat – not spherical!
 Implications?
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The Big Bang 10-35 seconds
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generates space & time, as well as all the matter &
energy universe will ever hold
For small fraction of a sec., the universe is an
infinitely dense, hot fireball
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The Universe Takes Shape -- 10-6 sec.
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universe continues to expand → less dense & cooler.
now basic forces in nature become distinct:
 Gravity & “strong force” (holds nuclei of atoms together),
followed by the weak & electromagnetic forces.
 By end of 1st second, universe consists of particles & energy
-- smash together → form protons & neutrons.
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Formation of Basic Elements -- 3 sec.
nuclei of simple elements hydrogen, helium
and lithium form
 (will be another 300,000 yrs before electrons
are captured into orbits around these nuclei to
form stable atoms).
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The Radiation Era -- 10,000 years
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most of the energy left from the “fireball” is in
the form of radiation - different
wavelengths of light, X rays, radio waves
& ultraviolet rays
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Birth of Stars & Galaxies -- 300 my after BB
(still ~ 12 to 15 by before the present).
 pockets
of gas become more and more dense as a
result of gravitational attraction.
 Stars ignite within these pockets
 groups of stars become the earliest galaxies.
•Birth of the Sun -- 5 Billion Years Before Present (BP)
• Sun forms w/in cloud of gas in spiral arm of Milky Way
Galaxy.
• vast disk of gas & debris swirls around new star → gives
birth to planets, moons, & asteroids .
Looking at the night sky is
literally looking into the
past!!