First off, someone needs to explain what we're looking at. I'd also like someone to tell me the origin/history of the H-R diagram. Next, I need people to add information that hasn't been included. You'll need a better look at the diagram, so feel free to download the picture file to view it's details.
Take a look at this periodic table. It shows the nationalities of the discoverers of the various elements. First find out when a section was discovered and then come up with reasons why you these countries made these discoveries and not other countries around the world. In other words, from the standpoint of what was historically happening at the time, why did these countries make these discoveries. It might be best if you just looked at a single group.
This blog is for you...
Feel free to share some curious train of thought you have, as well as share your thoughts on others.