PRACTICAL EXERCISE 2: Model of the expanding Universe

This activity aims to illustrate the expansion of the Universe. You are going to create a model of the expanding Universe.

2.1 You will need one balloon, a flexible metric ruler and a paper strip for conducting measurements, a copy of this page, and a marker.

2.2. Use the markers to make 10 - 15 dots on the balloon and number 10 of them after the balloon is partially inflated.

2.3. Inflate balloon with 4 medium breaths to about the size of your fist; do not over inflate the balloon!

2.4. Bend the end of the balloon down and paper clip it so that no air escapes.

2.5. Record below what happens to the dots. Be very specific - use complete sentences.

2.6. Measure and record the distance between dot number one (your "home" dot) and neighboring dots with the METRIC RULERS. Be careful not to indent the balloon by pressing on it.

2.7. Now measure and record the distance between dot number one (your "home" dot) and the other 10 dots with the paper strip. Note any differences in the two measuring techniques.

2.8. Double the size of the balloon by inflating it slowly; do not over inflate the balloon! Measure and record the data from the enlarged balloon using both tools.

2.9. Answer the summary questions below.

a. If the dots represent galaxies, do they get larger as the balloon expands? Why do you think this is or is not so?

b. What relationship exists between the speed of the galaxies moving apart and their initial distance from one another? Name this Law.

c. Which measuring tool was more accurate? Why?

d. What is harder for the astronomer to measure: A galaxy's redshift (indicating recessional velocity) or its distance from Earth? Why? Explain your answer.