Chapter 5
The Universe and Solar System
The universe consists of all matter,
energy, and space that have
existed since the beginning of
time.
What makes up the universe?
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Stars, planets, satellites, asteroids, comets,
meteoroids, interstellar dust and gas
Stars are clustered together in large groups
known as galaxies.
Galaxies are classified into groups based on their
shape.
Spiral Galaxiesa. Shaped like a flat disk or pinwheel
b. Bright, bulging central core which
contains densely packed older stars.
Elliptical Galaxiesa. Range from spherical to elliptical in
shape
b. Contain older stars and do not develop
new stars
Irregular Galaxiesa.
b.
Oddly shaped
Sometimes resemble an explosion frozen
in time
Milky Way Galaxya.
b.
c.
Spiral galaxy
Contains 200-400 billion stars
Our solar system is located inside it
Astronomical Unit
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Distances in space are so huge they are
difficult to understand.
Distances are usually measured relative to
the average distance between our planet
and the sun.
Distance between the sun and earth is 1
A.U.
Light-year
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Expresses distances to the stars
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It is the distance light travels in one year
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One light-year is about 9.46 trillion km
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Our nearest neighboring star is 4.3 light-years
away!!!
Earth to Sun Distance
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http://www.astrotom.com/getting_started/earthsun_distance.htm
Solar System Live
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http://www.fourmilab.ch/cgi-bin/Solar
Big Bang Theory
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Approximately 15 billion years ago the universe
was created
During this explosive event all matter and
energy in the universe came into being
All matter and energy were once concentrated
into a very small, dense object, about the size of
an atom
Big Bang Theory
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This small object suddenly expanded
outward, creating the beginning of space
and time.
As the mixture of matter continued
expanding outward and cooling, large
quantities of radiation were emitted into
space.
Big Bang Theory
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Over time, simple atomic particles
combined to form light elements like
hydrogen and helium.
Eventually with the evolution of stars,
heavier elements were formed.
Big Bang Video
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http://teachertube.com/viewVideo.php?vid
eo_id=48256&title=The_birth_of_the_uni
verse_big_bang_and_beyond#
http://www.history.com/video.do?name=T
he_Universe&bcpid=1398218663&bclid=1
475274665&bctid=1475165841
Big Bang Theory
The main evidence which supports this theory is
that scientists believe:
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the universe is expanding based on the outward
movements of stars and
the background cosmic radiation that exists
galaxies are moving apart at speeds proportional
to their distances (red shift-blue shift)
Evidence for Expansion of Universe
Color spectrum- ROY G BIV
When the source of light is moving away
from the observer at a high rate of speed
the color lines shift toward the red end of
the spectrum
Red Shift
Red Shift
Red Shift
The more distant a galaxy is:
1. The greater the red shift of its spectral
lines and therefore
2. The greater its expansion velocity
Distance of Galaxies and Red Shift
Blue Shift
As a star moves toward the Earth its
wavelengths compress and the lines of its
spectrum shift into the blue area.
Red Shift/Blue Shift & Sound
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Similar to the Doppler Effect
Red Shift/Blue Shift
Evidence Supporting the Big Bang
Theory
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The universe is uniformly expanding outward in
all directions.
Galaxies are moving apart at speeds
proportional to their distances.
Background radiation is found throughout space
in amounts that would be expected from a 15billion-year-old event.
Alternative Theories
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The Oscillating Universe
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The Steady State Universe
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Intelligent Design
Pulsating or Oscillating Universe
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The universe will NOT continue to expand
indefinitely.
Gravitational attraction of all the matter in
the universe will reverse the expansion.
This will cause objects to collapse back
together.
The Steady State Universe
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The universe is unchanging.
It never had a beginning and will never
have an end.
Intelligent Design
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Physical and biological systems observed
in the universe result from purposeful
design.
An intelligent being was the designer.
The universe did not come into being by
chance or by natural processes that
occurred on their own.
Classification of Stars
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Color varies due to the wavelength of light
they emit
Color also indicates a star’s temperature
 Red
light- cool star
 Blue light- very hot star
Brightness
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A star’s brightness (magnitude) can also
vary.
Apparent magnitude- how bright a star
appears to be
Absolute magnitude- how bright a star
really is
H-R Diagram
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Graph that shows the relationship between the
absolute magnitude and the temperature of
stars
Main sequence- majority of stars fall in this band
which ranges from cool dim stars to very hot
bright stars
These stars are stable.
HR diagram
Life Cycle of a Star
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Energy production in stars is caused by a
nuclear reaction.
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Fusion produces the star’s heat and light.
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Stars begin as nebula: a cloud of gas and dust.
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Nebula can break apart into smaller pieces and
become stars.
Life Cycle of a Star
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As some of the small pieces which broke
off from the nebula get close together, the
core temperature starts to increase.
Once the core is hot enough fusion
begins.
The energy formed in the core moves
outward and a new main sequence star is
formed.
Life Cycle of a Star
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As long as hydrogen remains available, the
star continues to produce energy through
fusion.
Once the hydrogen is depleted, the star
collapses and generates a large amount of
heat.
The release of heat causes the star to expand
rapidly and become a red giant or supergiant.
Life Cycle of a Star
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The giant star soon collapses and
explodes with a burst of energy.
During the explosion it loses its outer
layers.
The bright flare-up star is called a nova or
supernova depending on its mass.
Life Cycle of a Star
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The dying star shrinks into a white dwarf
which is a small dim star that is very
dense and hot.
Or the supernova collapses and the pull of
gravity is so strong that nothing can
escape, not even light, resulting in a black
hole.
Our Sun
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Stable, average-sized yellow star in the main
sequence
Hot, bright, gaseous ball that consists mainly of
hydrogen and helium
Surface temperature of about 5500 degrees
Celsius
Nuclear reactions produce heat and light
Light from the sun takes 8 minutes and 20
seconds to reach Earth.
Earth’s Position in the Solar System
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Ptolemy- developed an Earth-centered, or
geocentric, model of the solar system.
His model had the moon, sun, and five
other know planets all revolving around
the Earth.
Earth’s Position in the Solar System
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Copernicus- Proposed a heliocentric, or
sun-centered, model of the solar system
He determined that the sun was at the
center of our solar system and that all the
planets---including Earth---revolved
around the sun.
Gravity
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Every object in the universe exerts a
gravitational pull on every other object.
The greater the masses of two objects,
the greater the gravitational pull.
The farther apart two objects are, the
weaker the gravitational pull
Gravity
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Earth is more massive than the moon;
therefore, Earth has a greater gravitational
force and the moon revolves around the
sun.
The sun is more massive than Mars, so
the sun has a greater gravitational force
and Mars revolves around the sun.
Elliptical Orbits
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Orbit- The path of a body revolving
around another body, such as a planet
around the sun or an artificial satellite
around the Earth.
Law of Ellipses- The orbit of each planet is an
ellipse (an oval).
Kepler’s Laws of Planetary Motion
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1.
2.
3.
Johannes Kepler discovered three laws of how
planets move.
Law of Ellipses- The orbit of each planet is an
ellipse (an oval).
Law of Areas- When a planet is close to the
sun it travels faster than when it is farther
away.
Harmonic Law- Can calculate how long it takes
for an object to go around the sun
Orbits Within Our Solar System
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All objects that revolve around the sun are
influenced by the sun’s gravitational pull.
An object’s closest point to the sun is
called perihelion. Earth’s is during the first
week of January
An object’s farthest point is called
aphelion. Earth’s is during the first week
of July