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 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

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)-H 2 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 SPIRALELLIPITICAL 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

Evolution of Stars

THE EVOLUTION OF STARS DWARF STARS GIANT 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