1.  Select three of these learning objectives to be discussed. write a post which discusses the three learning objectives you have selected. (MAKE SURE TO LIST THE OBJECTIVE BEING USED)

There is a word length requirement for your initial post.   If you wish to receive full credit for your initial post, it must be at least 200 words long as measured by a word processor, such as, MS Word.  Chapter 20: Between the Stars: Gas and Dust in Space

1. Describe the next generation of ground- and space-based observatories.
2. Explain some of the challenges involved in building these observatories.
3. Explain how much interstellar matter there is in the Milky Way, and what its typical density is.
4. Describe how the interstellar medium is divided into gaseous and solid components.
5. Name the major types of interstellar gas.
6. Discuss how we can observe each type.
7. Describe the temperature and other major properties of each type.
8. Describe how we can detect interstellar dust.
9. Recognize the role and importance of infrared observations in studying dust.
10. Explain the terms extinction and interstellar reddening.
11. Define cosmic rays and describe their composition.
12. Explain why it is hard to study the origin of cosmic rays and the current leading hypotheses about where they might come from.
13. Explain how interstellar matter flows into and out of our Galaxy and transforms from one phase to another, and understand how star formation and evolution affect the properties of the interstellar medium.
14. Explain how the heavy elements and dust grains found in interstellar space got there and describe. how dust grains help produce molecules that eventually find their way into planetary systems.
15. Describe how interstellar matter is arranged around our solar system.
16. Explain why scientists think that the Sun is located in a hot bubble.