1. Astronomy: A Self-Teaching Guide
Ch. 07: The Universe
1. Define: Cosmology
2. What are two basic models of the universe?
3. When we look into space we see galaxies receding from us. What does this observation imply about the
universe?
4. In the Hubble diagram (right), the ____________________ a
galaxy’s distance, the ____________________ is its velocity
of recession.
5. Describe the Big Bang theory.
6. Compare the open and closed universe concepts.
Open Universe Closed Universe
7. Match the letters in the open
universe diagram to the following
description:
_____ Big Bang explosion took place
_____ Galaxies are still receding
_____ Galaxies formed
_____ Original hydrogen used up, the resulting cold, black universe will continue expanding indefinitely

2. 8. Match the letters in the open universe diagram to the following description:
_____ Big Bang occurred
_____ Galaxies formed and continued to recede
_____ Galaxies will stop
_____ Matter will be crunched together again (Big
Crunch)
_____ The universe will contract; galaxies will fall
back inward
_____ We live in an expanding universe; galaxies are
racing away from one another today
9. What is the oscillating universe?
10. What is the mysterious dark energy?
11. Describe the steady state theory.
12. Why does the observation of galactic evolution support the Big Bang theory?
13. The ____________________ known stars consist of mainly ____________________ and helium and lack
heavier elements. Newer stars contain heavy elements recycled from older generations of
____________________ that died and ejected their contents into space during ____________________
explosions
14. What is the significance of the cosmic background radiation?

3. 15. In general, how does the abundance of hydrogen and helium in stars support the Big Bang theory?
16. What is the age of the universe that was obtained by observation of the cosmic background radiation?
17. What is Olber’s paradox?