GoKawiilVulcan: the 19th-century 'planet' astronomers wrongly confirmed for decades
In the 1800s, astronomers proposed a planet called Vulcan orbiting the Sun inside Mercury's orbit, partly inspired by the successful prediction of Neptune based on anomalies in Uranus's orbit. Vulcan was reportedly sighted multiple times over roughly forty years and its properties were described in detail, even though it is now understood not to exist. What observers actually saw remains unexplained.
GoKawiil's interpretation of the reporting above, not reported fact.
The Vulcan episode is presented as a lesson in how confirmation bias and trust in prevailing theory can lead scientists to repeatedly 'confirm' something that isn't real. It suggests that even well-established methods, like the one that correctly predicted Neptune, can mislead when applied to anomalies later explained by entirely different physics (in Mercury's case, general relativity). The case is framed as a caution for how scientific consensus can persist despite shaky observational evidence.
- Vulcan was a hypothesized planet inside Mercury's orbit, proposed to explain orbital anomalies.
- Multiple astronomers reported sightings of Vulcan over about 40 years despite it not existing.
- The episode illustrates how scientific confidence can outpace actual evidence, a cautionary lesson for researchers.
Source: kevinboone.me — Kevin Boone, 2026-11-07
Published there as: “The planet Vulcan: a cautionary tale”
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