Editing Vulcan (hypothetical planet) (section)

== Hypothesis disproved ==
In 1915 [[Albert Einstein|Einstein]]'s [[theory of relativity]], an approach to understanding gravity entirely differently from [[classical mechanics]], removed the need for Le Verrier's hypothetical planet.<ref name="Clemence"/> It showed that the peculiarities in Mercury's orbit were the results of the curvature of spacetime caused by the mass of the Sun.<ref>[https://www.oddsalon.com/jan-2-1860-the-discovery-of-planet-vulcan/ Kurt Larson, Jan 2, 1860: The Discovery of Planet Vulcan, oddsalon.com]</ref> This added a predicted 0.1 arc-second advance of Mercury's perihelion each orbital revolution, or 43 arc-seconds per century, exactly the observed amount (without any recourse to the existence of a hypothetical Vulcan).<ref>William Sheehan, Richard Baum, Vulcan Chase - The Search for an Inside Planet, Astronomy Magazine, December 1997, page 47</ref>

The new theory modified the predicted orbits of all planets, but the magnitude of the differences from Newtonian theory diminishes rapidly as one gets farther from the Sun. Also, Mercury's fairly eccentric orbit makes it much easier to detect the perihelion shift than is the case for the nearly circular orbits of [[Venus]] and [[Earth]]. Einstein's theory was empirically verified in the [[Eddington experiment]] during the [[solar eclipse of May 29, 1919]], during which photographs showed the curvature of spacetime was bending starlight around the Sun. Most astronomers quickly accepted that a large planet inside the orbit of Mercury could not exist, given the corrected equation of gravity.<ref name="baron" />{{rp|p=220}}

The [[International Astronomical Union]] has reserved the name '[[Vulcanoid]]" for asteroids that may exist inside the orbit of the planet Mercury. So far, however, earth- and space-based [[telescope]]s and the [[NASA]] [[Parker Solar Probe]] have detected no such asteroids.<ref>[https://www.iau.org/news/pressreleases/detail/iau1303/ Names for New Pluto Moons Accepted by the IAU After Public Vote, Press Releases - iau.org, 2 July 2013]</ref>