Many astronomers in the past have believed to have seen a planet orbiting the Sun in front of Mercury. One of those astronomers
that was credited for the accounts was Urbain Jean Joseph Le Verrier. Le Verrier had proved the existance of Neptune, and
was ready to prove the existance of yet another planet, Vulcan.
Once Neptune was found, La Verrier was up to the task to make sure the planetary orbits of all of the planets did not contain
any errors. He had soon come to Mercury and wondered how come it did not follow Newton's laws. It had moved too fast around
the sun. It is small enough that Venus and Earth's gravitational pulls should be slowing it down. He believed that a planet
next to the sun had caused Mercury's awkward orbit.
Einstein had a theory to Mercury's orbit that later proved correct, but many people were still ingulfed in Newtonian theories.
There just had to be a planet there. The little black dot on the sun that was sometimes seen by the naked eye had to be Vulcan!
The eclipse of the Sun was to happen on July 29th, 1878. This would give a chance for Vulcan to be seen clearly across the
Sun's discs. However, the planet didn't appear. Astronomers associated with the discovery of the so-called Vulcan were discredited
and the search soon ended.