Section 12.1 Explaining the Early Universe
Section 12.1 Explaining the Early Universe
page 428
GALAXY –collection of stars, planets, gas and dust held together by gravity
PLANET (Earth) - SOLAR SYSTEM – GALAXY (Milky Way) - UNIVERSE
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
Astronomical UNIT = distance from the sun to Earth = ~ 150 million km
Hubble’s Proposal
•The Universe is expanding, galaxies are moving away from each other
•The further away the Galaxy, the faster it is moving
Evidence –Red Shift Analysis
•Based upon Electromagnetic Radiation (waves)
•A spectroscope allows astronomers to view patterns of different stars, thus astronomers can identify and determine patterns of stars it showed galaxies moving away from us.
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)- 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
-Starts to rotate as it collapses creating the solar system
Section 12.2 Galaxies and Stars
Galaxies occur in 3 shapes ( see diagram page 446)
- SPIRAL
- ELLIPITICAL
- IRREGULAR
Our Galaxy, Milky Way is spiral
Earth is on a spiral arm, we see the center on its side at night
Some of the oldest and largest galaxies are elliptical, more then 50% of galaxies are this shape
THE EVOLUTION OF STARS
DWARF STARS (low mass) Small, burn fuel slowly, last a long time (100 billion years) red dwarfs to white dwarfs and burn out
GIANTSTARS (intermediate to high mass stars)
Large, burn fuel quickly, last a short time RED GIANTS to white dwarf to black dwarf OR SUPER GIANTS supernova to neutron star to 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 super massive black hole as matter is attracted into itself
The Future of Space Exploration Careers Related to Space
Medicine, agricultural, industrial, meteorological
The Risks
The risks are high since people need so much to survive space. Food, fuel and water become harder to supply. Mechanical failure and hitting space junk is a large risk. Exposure to solar radiation
There is an ethical debate as to whether space travel is necessary and an appropriate receiver of the countries money.