- The Hertzsprung–Russell diagram (abbreviated as H–R diagram, HR diagram or HRD) is a scatter plot of stars showing the relationship between the stars’ absolute magnitudes or luminosities and their stellar classifications or effective temperatures. The diagram was created independently in 1911 by Ejnar Hertzsprung and by Henry Norris Russell in 1913, and represented a major step towards an understanding of stellar evolution.
- Colour in the Middle Ages (medievalists.net)
Every society harbours unique and intriguing perspectives on colours—what they symbolize, which ones are deemed more aesthetically pleasing, and which should be avoided. French historian Michel Pastoureau has unearthed fascinating insights into the medieval period’s relationship with colour. Here are seven vivid facts about colour in the Middle Ages based on his research.
