The planet Vulcan was originally theorized to exist to account for Mercury's perihelion precession. Many astronomers believe they saw evidence of it, but all research was suppressed because of the Einstein gangsters hijacking science back then.

http://en.wikipedia.org/wiki/Vulcan_(planet)

You might take a look at Gerber's theory, too.

http://www.google.com/search?q=gerber+mercury+perihelion&btnG=Search&hl=en&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&hs=9Hz&sa=2

Bill G: The planet Vulcan was originally theorized to exist to account for Mercury's perihelion precession. Many astronomers believe they saw evidence of it, but all research was suppressed because of the Einstein gangsters hijacking science back then.

http://en.wikipedia.org/wiki/Vulcan_(planet)

cinci: Right Bill, and nobody has made any astronomical observations since 1859 that might confirm or deny the existence of Vulcan. Of course those astronomers were working with 3.5 to 7 inch telescopes so today's McMath-Pierce telescope with it's 1.6 meter telescope wouldn't have a chance of finding Vulcan. And even if it could no, real astronomer would reveal that he had found a new planet because none of them like fame or would want to have a planet nemed for them, right?