Pierre Janssen

Events

1

Episodes

3

Years

1868

Every event in Historedia whose sources name Pierre Janssen, with the role they cite and all of that event’s episodes. This is not a biography, and mentions are grouped by name, so two people with the same name can share this page.

Events and episodes

1. Norman Lockyer identifies the D3 spectral line and proposes helium

   1868

   Role: French scientist who independently observed the spectral line during the 1868 eclipse

   1. 11868 · LondonObservation of the D3 Line

      Lockyer observed a prominent yellow line in the solar spectrum from London, concluding it was caused by an unknown solar element.

   2. 218 August 1868 · UnknownJanssen's Eclipse Observation

      Pierre Janssen observed the yellow line during the total solar eclipse of August 18, 1868.

   3. 3Unknown · UnknownNaming of Helium

      Lockyer named the proposed unknown element helium, derived from the Greek word for the Sun.

Sources

1. Norman Lockyer Wikipedia, revision of 2026-09-23
2. Helium Wikipedia, revision of 2026-10-01