Vulcan (hypothetical planet) Vulcan (hypothetical planet) Vulcan is a small hypothetical planet that was proposed to exist in an orbit between Mercury and the Sun. Attempting to explain peculiarities of Mercury's orbit, the 19th-century French mathematician Urbain Le Verrier hypothesized that they were the result of another planet, which he named "Vulcan". A number of reputable investigators became involved in the search for Vulcan, and despite occasional claimed observations, no such planet was ever confirmed. Peculiarities in Mercury's orbit have now been explained by Albert Einstein's theory of general relativity. Searches of data gathered by NASA's two "STEREO" spacecraft have failed to find
The Secret of the Ninth Planet Plutonians dead, the danger to the solar system is past. Burl sees then the people of other planets and of other stars coming together in peace and mutual understanding. The book was reviewed by “When the power of the sun becomes noticeably diminished, young Burl Denning and his expedition take off in an anti-gravitational ship to discover the cause and its location. After a dizzying tour of all the planets, they realize that the trouble springs from Pluto, a belligerent planet which is trying to usurp the life-giving power which the sun gives earth. Making an alliance with the friendly