1. Chapter 12
Space Exploration

2. Explaining the Early Universe
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
first astronomer to
identify other
galaxies besides
the milky way.
UNIVERSE
GALAXY – Milky Way
SOLAR
SYSTEM

3. 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

4. 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

5. THEORIES OF THE ORIGIN OF THE UNIVERSE

6. 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.

7. 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

8. THEORIES OF THE ORIGIN OF THE SOLAR SYSTEM

9. STELLAR COLLISION THEORY
This Theory says that Our Solar System was created from the spin off of colliding stars!

10. 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

11. -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

12. and answer the following questions: p. 443 #s 1,5,6,7,8,9,11,12.
TASK
Read Section 12.1 in the textbook
and answer the following questions: p. 443 #s 1,5,6,7,8,9,11,12.

13. p. 433 1. Hubble noticed that all galaxies are
p 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.

14. 2. Our solar system formed more than 4.5 billion years ago.
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.

15. Galaxies and Stars Section 12.2 SPIRAL ELLIPITICAL
Our Milky Way Galaxy, Earth is on a spiral arm, we see the center on it’s side at night
Some of the oldest and largest galaxies are elliptical, more then 50% of galaxies are this shape

16. 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.

17. THE EVOLUTION OF STARS GIANT STARS Small
DWARF STARS
GIANT 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.
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

18. 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.

19. 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.

20. 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

21. 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.

22. The Future of Space Exploration
Pilots
Technicians
Engineer
Careers Related to
Space
Astronaut
Scientist
Doctor