The Planet Vulcan That Never Was

In the 1850s, the French astronomer Urbain Le Verrier noticed that Mercury did not behave. Its orbit drifted by a tiny, stubborn amount that Newton’s gravity could not explain. Le Verrier had a bold idea: an unseen planet, tucked between Mercury and the Sun, must be tugging it along.

The guess carried weight. Le Verrier had already used the same method to predict Neptune in 1846, simply by studying wobbles in Uranus’s path. So when he presented his new planet to the Academy of Sciences and named it Vulcan, after the Roman god of fire, astronomers across Europe rushed to find it.

The mathematics that conjured one world from thin air had failed to summon another.

Decades of searches turned up nothing solid. The answer arrived in 1915, when Albert Einstein’s general theory of relativity showed that Mercury’s odd orbit came from the curvature of spacetime near the Sun, no hidden planet required. Vulcan quietly vanished from the maps, a phantom dissolved by a deeper picture of gravity.