THE UNIVERSE CHAPTER 20

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Emmeline Greene
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1 THE UNIVERSE CHAPTER 20

2 THE UNIVERSE UNIVERSE everything physical in and Includes all space, matter, and energy that has existed, now exists, and will exist in the future. How did our universe form, how did evolve to what it is today, and what will it be doing in the future???

3 BIG BANG THEORY The most widely accepted theory of the universe today is the BIG BANG THEORY! BIG BANG THEORY: Occurred billion years ago All energy and matter was compressed into a single point that was infinitely dense and small That point began to extremely rapidly in a big bang

4 BIG BANG THEORY IMMEDIATELY AFTER THE BIG BANG The universe existed of pure energy The universe was extremely and quickly The universe began to allowing sub-atomic particles to form pulled atoms together into gas clouds that eventually formed stars, which eventually formed galaxies The universe is still today

5 EVIDENCE FOR BIG BANG THEORY Edwin Hubble 1929 Stated the universe is expanding Studied spectra color from galaxies He saw galaxies appeared to be red = galaxies moving away from Earth

6 EVIDENCE FOR BIG BANG THEORY BACKGROUND RADIATION Field of microwave radiation that comes from everywhere in the sky Discovered in 1965 Scientists believe the microwave radiation found to be everywhere in the sky are dim remnants of radiation produced during the big bang.

7 QUIZ How old is the universe believed to be? Immediately after the big bang, did the universe expand or contract? (is it still doing this today?) What force pulled atoms together as well as gas and dust to form stars and galaxies? What are the two pieces of evidence for the big bang theory? What does Hubble mean by a red shift?

8 STARS Star huge spheres of very hot plasma that give off and other types of radiation The sun is our largest star much closer to earth than any other star Light-year used to describe distances in space One light-year is the distance light travels in one One light-year = 9.5 trillion km/year

9 STAR FORMATION Most stars begin as, with clouds of gas and dust mainly containing hydrogen and helium Hydrogen and helium are pulled together by The gravitational pull creates very high pressure and very high temperatures causing nuclear to begin which converts matter into energy Stars give off this energy as heat, light, and other forms of electromagnetic radiation

10 STAR CLASSIFICATION - BRIGHTNESS Stars are classified by their: Color Size Brightness Mass

11 STAR CLASSIFICATION COLOR AND TEMPERATURE COLOR OF A STAR DETERMINES THE OF A STAR!!! This is because the temperature of a star determines the colors of light it gives off The hotter the star, the it appears The cooler the star, the it appears Our sun is a moderately cool star, it gives off mostly yellow light Temperature also affects Hotter stars give off more intense light than cooler stars

12 STAR CLASSIFICATION - BRIGHTNESS BRIGHTNESS Stars that are far away appear dimmer than closer stars that are the same size and temp. Cooler stars appear dimmer than hotter stars that are the same size and distance from Earth Small stars appear dimmer than larger stars that are the same temp. and distance from Earth

13 HERTZSPRUNG RUSSELL DIAGRAM Shows how the temperature and brightness of a star are related Graphs vs. absolute magnitude Use to learn how stars change as they As stars age and pass through different stages in their life cycles, their positions on the diagram change Most stars appear on a diagonal line in the diagram called the

15 QUIZ What is a light-year? Stars consist of what two elements that allow nuclear fusion to occur? The color of a star tells you what about the star? What 3 factors affect the brightness of a star? What does an H-R diagram show you about a star? On what part of an H-R diagram is the sun found?

16 GALAXIES Galaxy group of of individual stars, star, systems, star clusters, dust and gas bound together by gravity More than billion galaxies in the universe The closest galaxy to Earth is millions of light years away Galaxies are moving from Earth (Red Shift) Galaxies that are farther away have a greater red shift

17 GALAXIES Galaxies are classified based on: Size Shape 3 main types: Spiral Elliptical irregular

18 have spiral arms of gas, dust, and stars

19 contain little gas or dust and have round or oval shapes

20 do not have any particular shape

21 OUR GALAXY! THE MILKY WAY galaxy More than 100 billion stars Diameter more than 100,000 light years At the center is a bulge of stars, and then spiral arms of gas, dust, and young stars

22 QUIZ How many galaxies are believed to be in our universe? Do galaxies experience a red shift or a blue shift? How are galaxies classified? What are the 3 types of galaxies? What type of galaxy is the our galaxy? What is its name?

8/30/2010. Classifying Stars. Classifying Stars. Classifying Stars

8/30/2010. Classifying Stars. Classifying Stars. Classifying Stars Classifying Stars In the early 1900s, Ejnar Hertzsprung and Henry Russell made some important observations. They noticed that, in general, stars with higher temperatures also have brighter absolute magnitudes.