On March 26, 1859, a French medical doctor and amateur astronomer named Lescarbault claimed to have observed a planet closer to the sun than Mercury; he called it Vulcan. He calculated the planet's movements and sent the information onto Jean LeVerrier, France's most famous astronomer.

Le Verrier had already noticed that Mercury had deviated from its orbit. A gravitational pull from Vulcan would fit in nicely with what he was looking for. Le Verrier checked other reports and found that other astronomers had also seen a small black disk against the background of the sun. From his calculations Le Verrier came to the conclusion that Vulcan was 13 million miles from the sun and that it took twenty days to circle that star.

But there was controversy because some astronomers couldn't find Vulcan. Le Verrier explained it away by saying that most of the time the planet would be lost in the sun's glare. He said that the best time to observe Vulcan would be during a solar eclipse.

In time the motions of Mercury were fully explained by Einstein's theory of relativity. Vulcan does not exist, and never did; the hunt for it was finally abandoned after the total solar eclipse of 1929.