Vulcan (hypothetical planet)
Channel: 宇宙のすべての知識 プリンシピア
Date: 17/03/2019

Vulcan (hypothetical planet), by Wikipedia https://en.wikipedia.org/wiki?curid=44069 / CC BY SA 3.0

#Obsolete_scientific_theories
#Hypothetical_bodies_of_the_Solar_System
#Hypothetical_planets
#General_relativity
#Mercury_(planet)
#Solar_System_dynamic_theories
#Astronomical_hypotheses
#Tests_of_general_relativity
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 any vulcanoids that could have accounted for claimed observations of Vulcan. It is doubtful that there are any vulcanoids larger than in diameter. There are a number of Mercury-crossing asteroids, but all have a semi-major axis larger than Mercury's.

In 1840, François Arago, the director of the Paris Observatory, suggested to the French mathematician Urbain Le Verrier that he work on the topic of the planet Mercury's orbital motion around the Sun. The goal of this study was to construct a model based on Sir Isaac Newton's laws of motion and gravitation. By 1843, Le Verrier published his provisional theory on the subject, which would be tested during a transit of Mercury across the face of the Sun in 1843. As it turned out, predictions from Le Verrier's theory failed to match the observations.

Le Verrier renewed his work and, in 1859, published a more thorough study of Mercury's motion. This was based on a series of meridian observations of the planet as well as 14 transits. The rigor of t...