ISP 205, Section 3, Hufnagel & Stein Spring 1997
Distance to the Nearest Stars Activity

Take 2 minutes to form an activity group of three students, but NOT with the students sitting next to you. Rather, your choice must be with the students seated in front of and behind you. If you don't know their names, introduce yourself. 
                                        Name: ________________________


                                        Student Number: ______________


                                        Name: ________________________


                                        Student Number: ______________


                                        Name: ________________________


                                        Student Number: ______________

The Starting Point

We'd like you to think about how you conceptualize the distance to the nearest star to the Earth, Alpha Centauri, before we model that distance. Take five minutes for your group to come to a consensus about the answers to the two questions below. If you don't know the answer, take your best guess, as wrong answers won't count against you. Please do NOT discuss this with neighboring groups.

1. What is the probability that the Sun will crash into another star as it circles around the Galaxy? (This would severely disrupt our planetary system.)
A. high
B. medium
C. low

2. The Andromeda Galaxy is coming toward our Galaxy and in about 3 billion years we are likely to merge with it. When that happens, how likely is it that the Sun will collide with another star in Andromeda?
A. high
B. medium
C. low

STOP and participate in the "Grape Activity," where the Sun is modeled as a grape. How far is the distance to the next star, also modelled as a grape? Answer: About 100 miles.
After the activity, Answer the same questions above again, but this time write a few sentences as to why your answer is the best choice.

1. What is the probability that the Sun will crash into another star as it circles around the Galaxy? (This would severely disrupt our planetary system.)
A. high
B. medium
C. low
 WHY? 

The probably of the Sun colliding with another star is low for 
two reasons:  The first is that single stars like the Sun are very far
apart compared to their radius.  The second reason is that the disk
stars are all moving around in circular orbits in the disk, like Olympic 
runners on a track.
2. The Andromeda Galaxy is coming toward our Galaxy and in about 3 billion years we will merge with it. When that happens, how likely is it that the Sun will collide with another star in Andromeda?
A. high
B. medium
C. low
 WHY? 
Our Sun will probably not collide with another disk star in 
Andromeda because the disk stars in Andromeda are far apart too.  The
merger simulation shown in class shows that many disk stars are thrown further
away from the merged galaxy.  The stars don't merge, the galaxies do.
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Visions of the Universe

Beth Hufnagel's home page, email: bhufnage4@pilot.msu.edu
Bob Stein's home page, email: steinr@pilot.msu.edu