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Chapter 12
Space Exploration
Section 12.1
page 428
Explaining the Early Universe
GALAXY – collection of stars, planets, gas
and dust held together by gravity
-Edwin Hubble was the
UNIVERSE
first astronomer to
identify other
GALAXY – Milky Way
galaxies besides
the milky way.
SOLAR
SYSTEM
Measuring Distances in Our Universe
• The distance to most stars from Earth are millions of
AUs therefore:
-distances within our Universe are measured in light
years
1 light year = distance light will
travel in 1 year
= 9.5 trillion km
Speed of light = 300, 000 km/s
Hubble’s Proposal
• Edwin Hubble noticed that galaxies were not
staying still but they were moving away from
each other (based on red shift analysis)
• He proposed that the Universe is expanding,
and galaxies are moving away
from each other
•
•
The further away the Galaxy, the
faster it is moving
THEORIES OF THE ORIGIN OF THE
UNIVERSE
THE BIG BANG THEORY
• Since there is evidence that our Universe is
Expanding, it must have started somewhere!
• ~13.7 billion years ago there was a massive
explosion and very high temperatures ~ 1 billion
°C were reached
• Very Rapid Expansion of a tiny volume of space
• Open Universe – one that will Expand
forever. First described by Georges Lemaitre
in 1927.
THE OSCILLATING THEORY
• Closed Universe – one that will expand so far
and is then drawn back by gravitational
forces, all the matter will meet again in a “Big
Crunch”
– This theory says the Universe goes through a
series of bangs and crunches in an ongoing cycle
– Currently still expanding from the most recent
explosion
THEORIES OF THE ORIGIN OF THE
SOLAR SYSTEM
STELLAR COLLISION THEORY
• This Theory says that Our Solar
System was created from the spin
off of colliding stars!
NEBULAR HYPOTHESIS
Nebulae(Nebula)- clouds of Hydrogen
gas and dust between stars
- When pulled together by gravity, stars form
if hot enough
- A nearby exploding star could have caused a
shock wave which started the process
-As the cloud begins to collapse it starts to
rotate
-4.5 billion years ago, the Sun became
an active star and the leftover
material combined to form 8 planets,
and other smaller bodies such as
moons, asteroids, and comets.
-Not all the planets formed at the
same time or in the same way…the
inner planets were formed first
followed by the outer planets
TASK
Read Section 12.1 in the textbook
and answer the following questions:
p. 443 #s 1,5,6,7,8,9,11,12.
p. 433 1. Hubble noticed that all galaxies are
moving away from each other.
2. Hubble proposed that the universe is
expanding in all directions, and that the galaxies
have taken the same amount of time to reach
their present positions from an original starting
point.
4. The Oscillating theory states that the universe
is closed and that there is enough matter in
the universe to slow (because of gravity) and
eventually stop the expansion of the
universe. According to this theory, all matter
will meet again in a Big Crunch.
5. Cosmic background radiation is the radiation
left over from the Big Bang expansion.
p. 439
1. The nebular hypothesis of solar system
formation is that the Sun and planets formed
when a large nebula condensed and was
collected together by gravity.
2. Our solar system formed more than 4.5 billion
years ago.
3. Inner or terrestrial planets and outer or Jovian
planets.
4. The distances are too great to be measured in
astronomical units.
Section 12.2
Galaxies and Stars
SPIRAL
Our Milky Way Galaxy, Earth is
on a spiral arm, we see the
center on it’s side at night
ELLIPITICAL
Some of the oldest and largest
galaxies are elliptical, more
then 50% of galaxies are this
shape
What is a star?
Stars are hot bodies of glowing
gas that vary in size, mass and
temperature. The color of a star
is determined by its
temperature: the hottest stars
are blue and the coolest stars
are red.
THE EVOLUTION OF STARS
DWARF STARS
Small
Burn fuel slowly & last a long
time (100 billion years)
Red dwarfs eventually change
into very hot, but small, dim
white dwarfs and burn out.
GIANT STARS
Large, burn fuel quickly, last a
short time
RED GIANTS slowly shrink into a
white dwarf which may cool into
a black dwarf OR
SUPER GIANTS (massive starts)
collapse in a dramatic explosion
called a supernova and
eventually collapse to form a
neutron star or a black hole
The Life of a Star
Stage 1 – stars are born in Nebula and condense
into a large globule of gas and dust that contracts
under its own gravity
Stage 2 – The condensing matter begins to heat
up and glow forming Protostars.
Stage 3 – If there is enough matter the central
temperature reaches 15 million degrees and
nuclear reactions start.
Stage 4: The star begins to release energy
causing it to shine.
The Death of a Star
-When a star starts to run out of hydrogen fuel
I it becomes a red giant or a super giant.
- Red giants grow bigger and form a cloud of gas
called a planetary nebula. As it cools, it becomes a
white dwarf which will eventually run out of fuel
and die becoming a black dwarf.
-Red super giants may suddenly explode which
is called a supernova. After this explosion,
leftover star material may form a neutron star.
After a large mass star explodes, a large
amount of mass remains and the gravity of the
mass is soo strong that the gas is pulled
inward, decreasing its volume. Eventually,
the gravity is soo strong that nothing can
escape, including light. The massive star then
becomes a black hole.
BLACK HOLE
• Sphere of extremely dense material
with a gravitational pull so strong
not even light can pass out of it!
• Created when a SUPER GIANT star
collapses in on itself
QUASAR
• Region of extremely high energy
which develops around a
supermassive black hole as matter is
attracted into
itself
•This energy
makes them the
brightest objects
in the universe.
The Future of Space Exploration
Pilots
Technicians
Engineer
Careers Related to
Space
Astronaut
Scientist
Doctor