104 years ago today, on December 12th, 1921 (November 14th, 1921 in the lunar calendar), American female astronomer Henrietta Levitt died. Henrietta LeVert On December 12, 1921, Henrietta LeVert, American female astronomer, dies. Henrietta Levitt is an American astronomer, deaf and mute, and the discoverer of the relationship between the Cepheid variable star Zhou Guang. LeVert was born in 1868 in Lancaster, Massachusetts, United States. In the 1890s, Pickering, an astronomer at Harvard University Observatory, recruited some deaf-mute women to measure and classify the photographic plates taken by the Observatory. In 1893, Levert took part in the work as one of them. In her work, she noticed that the longer the light change period of some variable stars in the small Magellanic cloud, the greater the brightness change. In 1908, she published the preliminary results in the annual report of Harvard University Observatory. After further research, the circumferential light relationship of Cepheid variable stars was finally confirmed in 1912. Levitt was often plagued by health problems and family firms during his time at the Harvard University Observatory. In 1921, American astronomer Shapley became the director of this observatory, and Levitt began to lead the stellar photometry work of Harvard University Observatory. At the end of the same year, Levitt died of cancer. The discovery of the circumferential light relationship of Cepheid variable stars is of great significance in astronomy. In 1913, Danish astronomer Hertzprong used the parallax method to measure the distance of several close Cepheid variable stars in the Milky Way galaxy, and the distance scale was calibrated. In 1915, Shapley successfully solved the problem of calibrating the zero point of Cepheid variable stars. Then Hubble, a famous American astronomer, used Cepheid variable star to measure the distance of Andromeda Nebula and confirmed that it was an extragalactic galaxy. In honor of this female astronomer, asteroid No.5383 and a crater on the surface of the moon are named after her "Levitt". Comments: A well-known female scientist