Is there any connection between the hypothetical planet Vulcan and the fictional planet Vulcan?

Question

For some time in the 19th century, it was believed that certain observed anomalies in the orbit of Mercury could be explained by the presence of a planet even closer to the sun, which was dubbed "Vulcan." Nobody ever found Vulcan, and eventually Einstein showed that these anomalies could be explained by general relativity instead.

Given the mythological names used for all the other planets in the Solar system, "Vulcan" is a pretty obvious name to use (especially for a hot planet). But it's still kind of funny that it's the name of both a very well-known fictional planet and a very well-known theorized-but-nonexistent planet.

Is there any evidence that Roddenberry was thinking of the hypothetical 19th-century planet when he named Spock's homeworld? Or did he get the name straight from Roman mythology?

Answer 1

Probably not.

According to Memory Alpha

Spock's homeworld was originally to have been Mars. At a time when Vulcans were known as Vulcanians, their home planet was to have been named Vulcanis. (Star Trek: The Magazine Volume 1, Issue 2, p. 82) This name was in fact used in an NBC promotional booklet announcing the first season of Star Trek: The Original Series, the 1966/1967 season.

The name was also used during early production of that first season but was changed to "Vulcan" soon thereafter. ("Amok Time" text commentary, TOS Season 1 DVD) The planet was referred to with that name in the final draft script of "Mudd's Women" (dated 26 May 1966), in which Kirk admitted to having been on Vulcan (though he didn't go into any further detail about the planet).

It seems more likely that the reference was to the mythological Vulcan rather than the putative astral object.

The look of Star Trek's Vulcan wasn't even decided upon until TOS Season 2 when Amok Time aired so any relation to a hot planet (such as the proposed missing planet) seems unlikely.

In the first scripted [for Amok Time] description of an orbital view of the planet, Vulcan is characterized as "a 'hot' planet... yellow, orange... no cool colors about it."