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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
UNIVERSE
GALAXY – Milky Way
SOLAR
SYSTEM
Measuring Distances in Our Universe
• 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
• The Universe is expanding, 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
• Very High Temperatures ~ 1 billion °C
• Very Rapid Expansion Open Universe – one
that will Expand forever
THE OSCILLATING THEORY
• Closed Universe – one that will Expand so far
and 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)-H2 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
-Starts to rotate as it collapses
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
Evolution of Stars
THE EVOLUTION OF STARS
GIANT STARS
DWARF STARS
Small,
burn fuel slowly,
last a long time (100 billion
years)
Dwarf star →red dwarfs →
white dwarfs → burn out
Large, burn fuel quickly, last a
short time
RED GIANT → white dwarf →
black dwarf
OR
SUPER GIANT→ supernova→
neutron star →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