Henry Draper Catalog

The Henry Draper Catalog is an astronomical survey that classifies stars based on their spectral characteristics, which help in understanding their temperature, composition, and other properties. Created in the late 19th and early 20th centuries, it was named after the American physician and astronomer Henry Draper. The catalog contains detailed information about over 300,000 stars, providing a foundational resource for astronomers. By organizing stars into spectral classes, it helps researchers study the universe's structure and evolution. Its impact remains significant in both professional astronomy and educational contexts.