Science Buddies: "Ask an Expert"

I am doing the project titled: Finding the Center of the Milky Way Galaxy Using Globular Star Clusters. In step 10, it just says "Are the three constellations near each other? Most of the Milky Way's globular clusters should be in the direction of the center of the galaxy. WHERE DO YOU THINK THE CENTER OF THE GALAXY IS". How do I find where the center of the galaxy is? I am aware that the 3 constellations found in step 4 of this project form a triangle and I am confused as to what to do now. I am stuck and cannot progress. I don't where to think it is ( I am aware it is in the triangle of the constellations with the most clusters in them) but how do I find WHERE in this triangle the center of the Milky Way is?

Hi UnicornFarts,

How you handle this part of the project is really up to you. You could say, "Based on this data, the center of the galaxy is somewhere in between where constellations X, Y, and Z are located in the sky. That's a completely valid way of drawing conclusions from the limited dataset you have available. If the true center of the galaxy lies in that region of space, then you know that the conclusion you drew from the data you had was correct.

Alternatively, you could try to calculate an "average" of the locations of the three constellations. If you took this approach, then instead of your conclusion saying that the center of the galaxy lies in between constellations X, Y, and Z, you would be able to say that, based on your data, you think the center of the galaxy is in a specific celestial coordinate. One way to "average" the location of the three constellations would be to find the centroid of the triangle formed by the three constellations. You can learn about how to find the centroid of a triangle here:

http://www.dummies.com/how-to/content/h ... angle.html

Either of these two approaches is valid. The key thing to to explain how you drew your conclusion from the data you collected.

Post back as you have other questions!

Hello UnicornFarts,

Adding to tdaly's answer, you could also base your answer off of the Right Ascension and Declination of the globular clusters, both of which measure angles which are formed during the orbits of the globular clusters. Using this data will give an extremely precise value. I've attached a few articles on Right Ascension and Declination, as well as how to calculate them, below: (Please be aware that tdaly's answer may be easier to calculate, as calculating Right Ascension and Declination probably involves high school/undergraduate level physics)

http://www.education.com/science-fair/a ... -clusters/

http://www.physics.csbsju.edu/astro/sky/sky.11.html

http://www.stargazing.net/kepler/altaz.html