Lab 9: Photometry and Constructing Color-Magnitude Diagrams Distance is all important in astronomy - astronomers need to know how far away things are in order to discover how they work and thus how the Universe works. Because things are so far apart in the Universe, actually going to the object and measuring the distance with a ruler is impossible. Therefore, astronomers must use other methods and proxies. Astronomers also want to know age because otherwise, we can't understand how the Universe works and how physics works. We also want to know how long the Universe has been around. One thing an astronomer can measure is a star- how much light is coming from it and what the spectrum looks like to determine the properties of it (like composition, spectral type, if it's a giant). An astronomer can use both of these observations to determine the distance to the object and this activity will take you through the beginnings of the logic, reasoning, and methods of doing this. First, we must understand the things tha