The universe is constant- Measure the ly expanding and chang- distances again. ing, To create a model of the expanding universe, you will Measure the distance need a balloon, a tape measure. between "S"dot and a binder clip, and a marker. all of the other dots. Inflate the balloon to the size of a grapefruit, then clamp the balloon neck with a binder clip. Mark a point "S" as the starting point near the equator of the balloon. Meas- Inflate the balloon ure 5-mm intervals along the to twice its size. equator and mark 10 to 15 12 13 14 15 6 12 13 14 15 S 1 2 3 dots evenly spaced. Label the dots with numbers. Measure the distance from $ to point 1 and record the distance. Now measure the distance between S and the other points. Record the data. Inflate the balloon until it. is twice its size and clamp the neck of the balloon. Repeat the process of measuring the dis- Do the dots get larger or smaller as the balloon expands? What tance between the starting dot and the other dots using the same do the dots represent? What is expanding-the galaxies or the technique, recording the distance from $ to each of the points. space between galaxies? Compare this to the idea of the expand- Calculate the distance the point moved by finding the initial ing universe. distance from dot 1 and the final distance from dot 1. Calculate the What is the relationship between the points on the balloon and change from before to after by subtracting initial distance from dot the galaxies in space? What pattern do you see? 1 from final distance from dot 1. Follow the procedure to calculate When you deflate the balloon what happens? List some of the the distance traveled by all the points. evidence on the origin of universe