- Chicago is the home of the blues and the truth of jazz, the heart of comedy and the idea of the skyscraper. Here, the age of railroads found its center, and airplanes followed suit. “Stormy, Husky, Brawling / City of Big Shoulders,” Chicago is a Heartland boomtown, its ethos defined by urban planner Daniel Burnham’s immortal vision: “Make no little plans; they have no magic to stir men’s blood.” It is one of the world’s great cities.
- Hertzsprung–Russell diagram (Wikipedia)
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.