Episode 2 of 3
Janssen's Observation
- When
- 18 August 1868
- Where
- Guntur, British India
Janssen observed a bright yellow line in the solar chromosphere during the total eclipse at Guntur, British India, on 18 August 1868.
Janssen noticed bright lines in the spectrum of the chromosphere, showing it was gaseous. The line had a wavelength of 587.49 nanometers. He realized the chromospheric spectrum could be observed without an eclipse, leading to his method for observing prominences in daylight.
Sources
- Pierre Janssen Wikipedia, revision of 2026-08-12
- Helium Wikipedia, revision of 2026-10-01
Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.