The Planet That Wasn't There
For decades, astronomers hunted a hidden planet closer to the Sun than Mercury. During an eclipse in 1878, two of them said they'd seen it.
What was reported
In 1859, the French mathematician Urbain Le Verrier, who had predicted the planet Neptune, argued that Mercury's orbit could be explained by an unseen planet even closer to the Sun. It was named Vulcan, and astronomers searched for it for years.
On 29 July 1878, a total eclipse crossed the American West. The astronomer James Craig Watson, watching from near Rawlins, Wyoming, and Lewis Swift in Colorado both reported seeing a star-like object near the Sun where Vulcan should be.
Explanations offered
What they saw were probably known stars, misidentified in the rush of a short eclipse. In 1915, Einstein's theory of general relativity explained Mercury's orbit without any extra planet, and Vulcan vanished from astronomy.
- When
- 29 July 1878
- Where
- Rawlins, Wyoming, USA
- Witnesses
- Astronomers watching a total eclipse
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
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