I have had a lot of requests for a boy version of my inverse-square print. I didn't want to use the same formula (even though I really do love inverse-square relationships), so! Going back to my undergrad astronomy classes for this one.
The Hertzprung-Russell diagram charts out the relative ages and phases of stars. People have tried to push for more logical names for the diagram like the luminosity-cuteness diagram, but no. Hertzprung-Russell is just too catchy!