Solar Helium Spectrum
Observes a new yellow spectral line during a solar eclipse.
Historical biography archive · Updated 2026-11-03
Pierre Jules Cesar Janssen Biography and Timeline
Follow Pierre Jules Cesar Janssen through 3 dated historical records for France.
Pierre Jules Cesar Janssen, historical timeline
A chronological timeline drawn from matching World History Database records.
3Distinct records
1 of 1Page
1868–1874Years on this page
1868
Yellow Solar Spectral Line
Provides evidence for helium in the Suns atmosphere.
1874
Transit of Venus Photography
Janssen uses his photographic revolver during the transit of Venus to record a rapid sequence of solar images.
Records, sources and methodology
These dates and descriptions come from the historical_events database. Exact duplicate records have been collapsed. Names are grouped by the country, Name 2 and Name 1 fields; records with missing Name 2 cannot be reliably assigned to an individual biography. Check the underlying sources before formal citation.