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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