Why Is It So Difficult To See The Rest Of The Milky Way?
Name: ______________________________________ Date: _____________________ Period:_______
Part of what makes our galaxy so hard to understand and see has to do with what’s in our galaxy and the vast distances
between objects in space. Use a variety of resources to help you find out more.
General Questions use the textbook to help you answer these, starts on 15.4, page 448
1. What is interstellar matter?
2. How does the density of gas in space compare to the density of the air we breathe on Earth?
3. Why is interstellar matter so important for the Milky Way?
1)
2)
4. How does interstellar matter impair our ability to examine the Milky Way?
5. A. What is scattering?
B. Does interstellar matter scatter light?
6. What is reddening?
B. Does interstellar matter lead to reddening?
7. Why does the Sun look red at sunset, and how is that similar related to what interstellar gases do to light?
8. A. What is the Zone of Avoidance?
B. Why is there a Zone of Avoidance? (i.e. What causes it and how?)
9. How do visible emission from Interstellar Gas help us study/see the Milky Way?
10. How do radio waves from cold Interstellar Gas help us study/see the Milky Way?
Distance Definitions:
1. A. What is the speed of light?
B. Can anything go faster than light?
2. What is a light year?
3. What is an astronomical unit?
4. What is a parsec?
5. A. Which of these distance units is smallest?
B. Which of these distance units is largest?
Parallax
Go to: http://tinyurl.com/pj8tnwo and answer these questions:
1. What is stellar parallax?
2. As the distance to a star increases, what happens to its parallax?
3. What is the full name of this powerful direct distance technique?
4. Because the even the nearest stars are very far away, how big are the largest measured parallaxes?
5. Why do we increasingly measure parallaxes from space?
6. Based on the formula for parallax, is the relationship between distance and parallax a direct relationship or an inverse
relationship?
7. What does Parsec stand for?
8. What is a parsec equal to in astronomical units, light years, and kilometers?
9. What is a light year?
10. What is a light year equal to in parsecs, and in astronomical units?
11. What is the big limitation of the parallax method?
12. What is the smallest measurable parallax from the ground?
13. Because of this, parallax is only good out to what distance?
14. How many stars are at this distance?
15. What was the name of the satellite mission that measured parallax to 100,000 stars?
Magnitude
Go to: http://tinyurl.com/ogu2pl4 and answer these questions:
1. What does the magnitude system specify?
2. In this magnitude system, what kind of objects have smaller magnitudes and what kind of objects have larger
numbers?
3. Fill in this magnitude scale with the representative objects given on the page:
4. What is the apparent brightness of a star observed from the Earth?
5. Star A has an apparent magnitude = 5.4 and star B has an apparent magnitude = 2.4. Which star is brighter and by
how many times?
6. What is absolute magnitude a measure of?
7. What is a star’s luminosity?
8. If you know a star's apparent magnitude and distance, what can you find?
9. A small, hot object can have the same luminosity as what?
10. Star luminosities are specified in units of solar luminosity which is relative to what?
11. The Sun generates a solar luminosity of …
Conclusion: What are some reasons for why it is so difficult to see and study the Milky Way?