A hypothetical planet whose orbit is said to lie between Mercury and the Sun, about twelve million miles from the Sun. Astronomers have no evidence of this planet as yet.

A hypothetical planet supposed to lie inside the orbit of Mercury, but always on the opposite side of the Sun from the Earth, making it invisible. Originally postulated to account for perturbations in planetary orbits, this planet is no longer supposed to exist by science, although some astrologers claim it as a sort of spiritual entity having power in a horoscope.

Vulcan is an intra-Mercurial planet orbiting the Sun every 18.6 days. The nature of Vulcan is combustible, fiery, explosive, and ethereal. Vulcan rules wind conditions, gases, gas-producing combustible materials like petrol and gun-powder etc. The existence of Vulcan has never been confirmed scientifically.

The god of fire, who presided over the working of metals; -- answering to the Greek Hephæstus.

Roman god of fire; known as Hephaistos to the Greeks

(Roman mythology) god of fire and metal working; counterpart of Greek Hephaestus

Vulcan is a pumice cone in Papua New Guinea. It is a sub-vent of the Rabaul caldera and lies on the western rim of the larger feature. Its most recent eruption was in 1994, when in conjunction with another vent, Tavurvur, the eruptions of Vulcan forced the abandonment of the city of Rabaul and the relocation of the local administrative centres.

VULCAN offers computational fluid dynamics for subsonic speed through hypersonic turbulent reacting and non-reacting flows on a variety of serial and parallel computational platforms.

Common term for a weapon that is often a craft's default or “main” armament, or weapons similar to it: generally shoots regular bullets straight ahead of the craft, though some “vulcan” weapons have a spread quality to them.

A very large Hong Kong based manufacturer of fireworks. Not to be confused with Vulcan UK, a UK display company.

Vulcan, based in Southport, England, made cars from 1902 until 1928 and commercial vehicles until 1953.