William Huggins was a pioneer in the field of spectroscopy. In 1881, he captured the first photographic spectrum of a comet. Credit: Courtesy of Linda Hall Library of Science, Engineering & Technology
Key Takeaways:
- Sir William Huggins obtained the first photographic spectrum of a comet (Comet 1881 III) on June 24, 1881, using a reflector telescope equipped for spectroscopy and astrophotography.
- Analysis of Huggins's photographic spectrum revealed the presence of cyanogen emissions.
- This discovery demonstrated that comets produce their own light, supplementing the previously understood reflection of sunlight.
- The detection of cyanogen in comets contributed to public anxieties surrounding the passage of Comet Halley's tail through Earth's atmosphere in 1910, leading to widespread fear and unusual preventative measures.
On the evening of June 24, 1881, Sir William Huggins directed his reflector, equipped with spectroscopic and photographic tools and located in his private observatory in London, to the head of Comet 1881 III. He captured the first photographic spectrum of a comet, and later analysis of the imagery revealed cyanogen emissions at certain wavelengths. This evidence showed that comets emit their own light, rather than solely reflecting sunlight. It also helped fuel panic 30 years later: When Earth passed through Comet Halley’s tail in May 1910, public fear mounted over predictions that its cyanogen gas could “snuff out all life,”  leading to bizarre precautions like gas masks, comet-protection umbrellas, and comet pills.
