Take an idealized galaxy made of 10^11 sun-like stars distributed in a disk that is 50 kpc in diameter and 1 kpc thick. We wish to build a scale model of the galaxy, substituting
a grain of sand and shrinking each star proportionally. (Assume R = 7 *10^8 m and R_sand= 1 mm).
a) What is the size of the model galaxy’s disk? Practically speaking is this a good scale to use for our model?
b) What is the average distance in km between stars (grains of sand) in our scale model?
c) Given what you have just learned from our scale model, do you expect stars to collide when two galaxies merge?