Episode 2 of 2

Publication

When: 1839
Where: Royal Observatory, Cape of Good Hope
Part of: Thomas Henderson publishes first parallax measurement of Alpha Centauri

Henderson published his parallax results in 1839, following Bessel's 1838 publication on 61 Cygni.

He withheld results initially due to suspicion they were too large. After Bessel published his own parallax, Henderson released his findings. This established Alpha Centauri as the second star to have its distance measured, as Henderson's work was not fully acknowledged at first.

Sources

Alpha Centauri Wikipedia, revision of 2026-10-03
Thomas Henderson (astronomer) Wikipedia, revision of 2026-08-29

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.