1. Mrs. Kettering 8 th Grade Science 2011

2. There is a lot of controversy over the age of our universe There is a lot of controversy over the age of our universe The most recent information came in April of 2007. From this study, the age of the universe is most likely 15-20 billion years. The most recent information came in April of 2007. From this study, the age of the universe is most likely 15-20 billion years. Keep in mind that as technology and our understanding of the universe expands, that estimate may change. Keep in mind that as technology and our understanding of the universe expands, that estimate may change.

3. Theory #1: Big Bang Theory States that everything began together at a point and a big explosion occurred that caused everything to move apart. Theory states that Theory states that galaxies are rapidly moving apart to this day Therefore, Therefore, universe is ever-expanding

5. Theory #2: Red Shift The spectrum of a star (or galaxy) reveals whether is it moving toward or away from the Earth If absorption lines are shifted slightly toward one end of the spectrum, it is an indication that the galaxy is moving relative to Earth. If absorption lines are shifted slightly toward one end of the spectrum, it is an indication that the galaxy is moving relative to Earth.

6. Theory #2: Red Shift Light reaching us from distant galaxies has its absorption lines shifted toward the red end of the spectrum which is referred to as the Red Shift – this means the galaxies are moving away from Earth If the absorption lines were shifted toward the violet end of the spectrum (which there is currently NO evidence of), the galaxy would be moving toward us If the absorption lines were shifted toward the violet end of the spectrum (which there is currently NO evidence of), the galaxy would be moving toward us

7. This image shows the shift on the spectrum as the galaxy is moving further away

8. Theory #3: Oscillating Theory Combines the Big Bang and Big Crunch theories (Red and Blue Shift Theories) The universe will expand until it cannot expand any more (Big Bang) and will then begin to contract (Big Crunch) … this will lead to another Big Bang and another universe.

9. The top image shows a galaxy that is NOT moving relative to Earth. The top image shows a galaxy that is NOT moving relative to Earth. The middle image shows a galaxy moving AWAY from Earth The middle image shows a galaxy moving AWAY from Earth The bottom image shows a galaxy moving TOWARD Earth. The bottom image shows a galaxy moving TOWARD Earth. Notice the shift on the spectrum for each possibility

10. Theory #4: Steady-State States that although the universe is expanding, the amount of matter is continuously increasing as well Therefore, Therefore, the average density of matter is staying relatively steady, and the look of the universe does not change

11. Galaxy – an organized system of hundreds of millions to thousands of billions of stars, sometimes mixed with interstellar gas and dust. Our Sun and Solar System are part of the Milky Way Galaxy Galaxies often appear to be distinct but fuzzy patches of light

12. In the 1920s, Edwin Hubble devised a classification of galaxies: In the 1920s, Edwin Hubble devised a classification of galaxies: 1.Disc-shaped Galaxies 2.Elliptical Galaxies 3.Irregular Galaxies

13. Disc-shaped (Spiral) Galaxy: flat disks that look like a spiral, with long arms winding toward a bright bulge at the center About 77% of the observed galaxies in the universe are disc-shaped galaxies About 77% of the observed galaxies in the universe are disc-shaped galaxies Milky Way Galaxy (our galaxy) is a disc- shaped galaxy

15. Elliptical Galaxy: have an ellipsoidal shape and a smooth, nearly featureless brightness profile Very little interstellar matter (gas or dust) Very little interstellar matter (gas or dust) No prominent internal structure No prominent internal structure

17. Irregular Galaxy: not disk-like or ellipsoidal and have no nucleus; chaotic, irregular appearance They have little symmetry in their shape They have little symmetry in their shape Most irregular galaxies were once spiral or elliptical galaxies that have been distorted and deformed by gravitational action from other, nearby galaxies Most irregular galaxies were once spiral or elliptical galaxies that have been distorted and deformed by gravitational action from other, nearby galaxies

19. Sun closest star to Earth – the next closest star is 39,900,000,000,000 km away (4.2 light yrs) Medium size Yellow Main Sequence Star 150,000,000 Km (93 Million miles) away. 4.5 - 5 billion years old Will last about another 5 billion years Located near the edge of our disc shaped galaxy – The Milky Way

20. Important Space Vocabulary: Comets - Rocky material made of gas dust and ice that orbit the sun Meteors - Space Rocks known as shooting stars when they enter the Earth’s atmosphere. Become meteorites when they hit the Earth’s surface Asteroids - Small rocky bodies known as minor planets Orbit the sun mainly between Mars and Jupiter (asteroid belt)

21. Stars Gigantic spheres of gas held together by gravity Generate huge amounts of energy because of nuclear reactions of hydrogen and other elements. Radiate electromagnetic radiation. – – Light, heat and other forms of energy There are 100 billion stars in our own galaxy!

22. Classifying Stars ClassColorSurface Temp. (degrees Celsius) Elements detectedExamples of stars O BlueAbove 30,000Helium10 Lacertae B Blue-white10,000 - 30,000Helium and Hydrogen Rigel, Spica A Blue-white7,500 - 10,000HydrogenVega, Sirius F Yellow-white6,000 - 7,500Hydrogen and heavier elements Canopus, Procyon G Yellow5,000 - 6,000Calcium and other metals The sun, Capella K Orange3,500 - 5,000Calcium and Molecules Arcturus, Aldebaran M RedLess than 5,000MoleculesBetelgeuse,Antar es

23. Hertzsprung-Russell Diagrams Shows the relationship between a star’s surface temperature and absolute magnitude/luminosity (brightness) Used to study the lives of stars – –Most stars lie along the main sequence portion of the diagram

24. HR-Diagram

27. Stages of a Stars Life Cycle

28. Important Star Vocabulary Nebulae - Giant clouds of gas and dust in space. Where new stars are formed. Supernova  gigantic explosion in which a massive star collapses – –Occurs after a massive star uses up its fuel source Black Hole  an object that is so massive that light cannot escape its gravity – – Believed to be the center of most galaxies – –Remnants of a supernova – –Astronomers can detect black holes by using X-ray telescopes

29. Light Years distances Unit of measurement for distances in space The distance that light travels in one year. Light travels at about 300,000 km/sec. – – 186,000 miles/sec One light year is equal to 9.46 trillion km (9,461,000,000,000). – – 5.87 trillion miles (5,870,000,000,000) Light travels faster than anything else known to man.

31. GALAXY FOLDABLE Read Pages 720-721 and/or use your notes to complete the following Galaxy Type 1 Description Example Galaxy Type 2 Description Example Galaxy Type 3 Description Example Picture representation of Galaxy