2Explaining the Early Universe Section 12.1page 428Explaining the Early UniverseGALAXY – collection of stars, planets, gasand dust held together by gravity-Edwin Hubble was thefirst astronomer toidentify othergalaxies besidesthe milky way.UNIVERSEGALAXY – Milky WaySOLARSYSTEM
3Measuring Distances in Our Universe The distance to most stars from Earth are millions of AUs therefore:-distances within our Universe are measured in lightyears1 light year = distance light willtravel in 1 year= 9.5 trillion kmSpeed of light = 300, 000 km/s
4Hubble’s ProposalEdwin 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 awayfrom each otherThe further away the Galaxy, thefaster it is moving
6THE BIG BANG THEORYSince 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 reachedVery Rapid Expansion of a tiny volume of spaceOpen Universe – one that will Expand forever. First described by Georges Lemaitre in 1927.
7THE 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 cycleCurrently still expanding from the most recent explosion
9STELLAR COLLISION THEORY This Theory says that Our Solar System was created from the spin off of colliding stars!
10NEBULAR HYPOTHESISNebulae(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
12and answer the following questions: p. 443 #s 1,5,6,7,8,9,11,12. TASKRead Section 12.1 in the textbookand answer the following questions: p. 443 #s 1,5,6,7,8,9,11,12.
13p. 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.
142. Our solar system formed more than 4.5 billion years ago. p. 4391. 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.
15Galaxies 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 nightSome of the oldest and largest galaxies are elliptical, more then 50% of galaxies are this shape
16What 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.
17THE EVOLUTION OF STARS GIANT STARS Small DWARF STARSGIANT STARSSmallBurn 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 timeRED GIANTS slowly shrink into a white dwarf which may cool into a black dwarf ORSUPER GIANTS (massive starts) collapse in a dramatic explosion called a supernova and eventually collapse to form aneutron star or a black hole
18The Life of a StarStage 1 – stars are born in Nebula and condense into a large globule of gas and dust that contracts under its own gravityStage 2 – The condensing matter begins to heat up and glow forming Protostars.Stage 3 – If there is enough matter the centraltemperature reaches 15 million degrees andnuclear reactions start.Stage 4: The star begins to release energycausing it to shine.
19The 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 gascalled a planetary nebula. As it cools, it becomes awhite dwarf which will eventually run out of fueland die becoming a black dwarf.-Red super giants may suddenly explode whichis called a supernova. After this explosion,leftover star material may form a neutron star.After a large mass star explodes, a largeamount of mass remains and the gravity of themass is soo strong that the gas is pulledinward, decreasing its volume. Eventually,the gravity is soo strong that nothing canescape, including light. The massive star thenbecomes a black hole.
20BLACK HOLESphere 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
21QUASARRegion of extremely high energy which develops around a supermassive black hole as matter is attracted intoitselfThis energymakes them thebrightest objectsin the universe.
22The Future of Space Exploration PilotsTechniciansEngineerCareers Related toSpaceAstronautScientistDoctor