Episode 2 of 3

Janssen's Eclipse Observation

When
18 August 1868
Where
Unknown
Part of
Norman Lockyer identifies the D3 spectral line and proposes helium

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

An observation of the new yellow line had been made earlier by Janssen at the 18 August 1868 solar eclipse. This observation occurred during a total solar eclipse with a magnitude of 1.0756.

Sources

  1. Norman Lockyer Wikipedia, revision of 2026-09-23
  2. Solar eclipse of August 18, 1868 Wikipedia, revision of 2026-08-22

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.