Both Period 2 and Period 4 classes will have their science test for chapt. 15 on Friday October 22. Now is a good time to begin studying!!!! Review Ch 15    2. a) Nebula, red supergiant, supernova, black hole b) one possible order, remnants of the supernova can begin the process again   c)extreme massive star 3. a) A nebula is a huge cloud of dust and gases, mainly hydrogen and helium gases. b) Stars and planets form from nebulas, and when a star's life cycle ends, much of the material turns back into nebula. 4) Stars reach old age when the fuel needed for nulcear fusion, hydrogen, runs out. 　 5. The force of gravity leads to the formation of planets 6. Most stars become white dwarfs, only massive stars become black holes 7) A White dwarf is the stage of the life cycle of a low- or medium mass star that follows the red giant stage. 8. a) Our sun will become a red giant and then white dwarf b) Sun will not go through the other stages because they are for high mass stars 10. Big Bang theory is used to explain the origin of the universe- it was once a small very dense, hot mass that exploded 11. Stars are too bright to see object nearby & planets are small. If stars wobble, good indication of planet orbiting it. 14) Other evidence supporting this theory is the faint glow of radiation observed from the initial Big Bang. Another is found inthe Hubble Deep Field image, which shows less structure to distance galaxies as well as colliding galaxies. 15.a)Continued red shift would indicate continuos expanding universe b) No more red shift - no more expanding c) Violet shift - indicate galaxies coming closer together.