The planet that never was

You've no doubt heard of the planet Vulcan, Mr. Spock's homeworld in the sci-fi universe of "Star Trek." But did you know that Trek's fictional Vulcan was named after a hypothetical planet thought to orbit close to the Sun?

The search for the real planet Vulcan began in earnest during the 19th century.

In the year 1859 the discoverer of the planet Neptune, the celebrated French astronomer Le Verrier, had learned of a report about a mysterious transit of an unknown object across the face of the Sun. Collecting data from the observer, Le Verrier scribbled the transit calculations on an envelope; the calculations demonstrated the very unusual nature of the planet Mercury's orbit around the Sun. The hot planet's excess precession (its direction change in rotation around the Sun) didn't quite follow the rules of Newton's laws of celestial mechanics, according to the great astronomer.

"Le Verrier published a thorough study of Mercury's motion. This was based on a series of meridian observations of the planet as well as 14 transits... During Mercury's orbit, its perihelion advances by a small amount each orbit, technically called perihelion precession. The phenomenon is predicted by classical mechanics, but the observed value differed from the predicted value by the small amount of 43 arc seconds per century," according to Richard Baum, author of "In Search of Planet Vulcan".

Of course, when the great Le Verrier spoke everyone listened - after all, the gentleman had discovered the planet Neptune in 1846. Surely, such genius must not be ignored.

What caused Mercury's puzzling precession? That was the rub. La Verrier was determined to solve the orbital mystery.

As 1859 slipped away, the world's scientific community was all ears in anticipation of Le Verrier's final solution to the Mercury problem.

Finally, on the morning following New Year's Day 1860, after months of mathematical doodling, with figures scribbled upon even more envelopes, La Verrier announced that he had the solution - a solution both he and the astronomical community would come to embrace (even though in hindsight, the solution required a large dollop of cr me brul e to go down easy).

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