1. Ch 30 con’t.

2. Black Holes black hole an object so massive and dense that even light cannot escape its gravity Some massive stars produce leftovers too massive to become a stable neutron star. These stars contract, and the force of the contratction leaves a black hole.

3. Black Holes How do we know they are there if they are invisible?? It is observed by its effect on a companion star. Matter from the companion star is sucked into the black hole by its gravity….just before the matter is absorbed, it swirls around the black hole. The gas gets so hot that X rays are released. This is how astronomers detect them. http://www.space.com/common/media/video/player.php?video Ref=black_holes

4. Constellations Because of the tremendous distance from which the stars are viewed, they appear fixed in their patterns. For more than 3000 years, people have observed and recorded these patterns. Such patterns of stars and the region of space around them are called constellations. http://www.youtube.com/watch?v=mDObFetwDiswww.youtube.com/watch?v=mDObFetwDis http://www.youtube.com/watch?v=qwbnjq3ntrU

5. Galaxy galaxy a collection of stars, dust, and gas bound together by gravity Galaxies are the major building blocks of the universe. Astronomers estimate that the universe contains hundreds of billions of galaxies.

6. Galaxy What is the name of our galaxy??? Milky Way!! A typical galaxy, such as the Milky Way, has a diameter of bout 100,000 light-years and may contain more than 200 billion stars.

8. Types of Galaxies Galaxies are classified by shape into three main types. A spiral galaxy has a nucleus of bright stars and flattened arms that spiral around the nucleus. Elliptical galaxies have various shapes and are extremely bright in the center and do not have spiral arms. An irregular galaxy has no particular shape, and is fairly rich in dust and gas.

9. Spiral Galaxy

10. Elliptical Galaxy

11. Irregular Galaxy

12. The Milky Way What type of galaxy is our Milky Way?? A. Spiral B. elliptical C. irregular A

13. Ok, so how did our Universe begin?? There are plenty of theories… Big Bang… Religious views… Everyone is entitled to what they believe. Since no one was alive when it all “happened”, everything is based on theories. Lets see what the big bang theory is all about.

14. BANG!

15. Mr. Hubble Edwin Hubble went to Oxford University to study law. He wasn’t happy as a lawyer and decided to return to his passion of studying space. Hubble had also devised a classification system for the various galaxies he observed, sorting them by content, distance, shape, and brightness.

16. Hubble found that the spectra of galaxies, except for the few closest to Earth, were shifted toward the red end of the spectrum. If the were shifted toward the red end of the spectrum, are the moving toward or away from the Earth?? AWAY!

17. The Expanding Universe Using Hubble’s observations, astronomers have been able to determine that the universe is expanding. The expanding universe can be thought of as a raisin cake rising in the oven. If you were able to sit on one raisin, you would see all the other raisins moving away from you. Similarly, galaxies in the universe are moving farther away from each other due to the expansion of the universe.

18. Big Bang Theory big bang theory - the theory that all matter and energy in the universe was compressed into an extremely small volume that 14 to 15 billion years ago exploded and began expanding in all directions

21. Cosmic Background Radiation cosmic background radiation - radiation uniformly detected from every direction in space; considered a remnant of the big bang. Astronomers believe that cosmic background radiation formed shortly after the big bang. The background radiation has cooled after the big bang, and is now about 270°C below zero.

22. Cosmic Background Radiation

23. Ripples in Space Maps of cosmic background radiation over the whole sky show ripples. These ripples are irregularities caused by small fluctuations in the distribution of matter in the early universe, and may indicate the first stages in the formation of the universe’s first galaxies.

24. Dark Matter Analysis of the ripples in the cosmic background radiation shows that the matter that humans, the planets, the stars and the matter between the stars makes up only.4% of the universe. About 23% of the universe is made up of a type of matter that does not give off light but that has gravity. This type of matter is called dark matter.

25. Dark Energy Most of the universe is made up of an unknown material called dark energy Scientists think that dark energy acts as a force that opposes gravity. Many scientists think that some form of undetectable dark energy is pushing galaxies apart.

26. POP QUIZ!! Take out a sheet of paper!

27. 1. What is a galaxy? a. stars, dust, and gas bound together by gravity b. debris, dirt, and trash bound together by gravity c. air, gas, and rock in the universe d. planets, moons, and stars bound together by magnetism

28. 2. What is important about Hubble’s discovery that there is a red shift in the spectra of galaxies? a.It suggests that the universe is contracting. b.It suggests that the universe is expanding. c.It proves the big bang theory. d.It suggests the existence of black holes.

29. 3. What is an irregular galaxy? a.a galaxy with no particular shape b.a galaxy shaped like a stretched-out football c.a galaxy that has vast areas without stars d.a galaxy that has high mass and is rich in dust and gas

30. 4. A spiral galaxy has a nucleus of a. dim stars, and spiral arms consisting of billions of young stars. b. bright stars, and spiral arms consisting of billions of young stars. c. bright stars, and spiral arms consisting of billions of old stars. d. dim stars, and spiral arms consisting of billions of old stars.

31. 5. Astronomers believe that cosmic background radiation formed A. about a billion years ago. B. more that a trillion years ago. C. shortly after the big bang. D. shortly before the big bang.

32. 6. The big bang occurred about a. a billion years ago. b. 5 billion years ago. c. 14 million years ago. d. 14 billion years ago.

33. Bonus! 7. A rapidly spinning neutron star that emits bursts of radio and optical energy is a a. supernova. b. black hole. c. red giant. d. pulsar.