On this day, 68 years ago, on February 18, 1957 (January 19, 1957 in the lunar calendar), Russell, an American astronomer and one of the founders of modern astrophysics, passed away. Russell Russell (1877-1957), American astronomer and one of the founders of modern astrophysics and stellar astronomy, died on February 18, 1957. He was 80 years old. He developed the relationship between star brightness and spectral type and proposed a method to calculate binary stars, which had a profound impact on the development of astronomy in the 20th century. In 1929, Russell carefully studied the solar spectrum and proved that the amount of hydrogen in the sun was surprisingly high. He concluded that hydrogen accounted for three-fifths of the sun's total volume. Independently with Danish astronomer Hertzplon discovered the relationship between star luminosity and surface temperature through stellar spectral research, known as the famous "Herro diagram".