Star Trek: 10 Things You Didn’t Know About Vulcans
6. My Very Easy Method Just Speeds Up Naming Vulcan
In 1860, French astronomer and mathematician Urbain Le Verrier, who had previously discovered Neptune, announced to the world in Paris that he'd found yet another planet, this time in the inner solar system, and it was to be called Vulcan. Originally predicted as a way to explain the precession of the perihelion of Mercury within Newtonian mechanics, Le Verrier's supposed observation of Vulcan was controversial, and eventually Einstein's equations put paid to the need for its existence. The myth and the name lived on, however, and not least in Star Trek.
In Gene Roddenberry's original pitch, Spock and species were from Mars, but by the time NBC was promoting the first season of The Original Series, the 'Vulcanians' were from 'Vulcanis,' quickly becoming the Vulcans from Vulcan as the episodes aired. According to Star Trek: Star Charts (2002), Vulcan is located in orbit of the (real life) star 40 Eridani A — part of a trinary system, with binary pair B and C at about 400 AUs from A.
The Eridani location, which originated in James Blish's 1968 short story adaptation of Tomorrow is Yesterday, has been widely used in other reference materials, and Roddenberry himself approved the idea in a letter for the July 1991 issue of Sky & Telescope magazine.
In the Star Trek: Enterprise episode Home, the distance between Earth and Vulcan was given as 16 light-years for the first time. Within half a light-year, this matches the actual distance between Earth and 40 Eridani A.