Mercury (planet) Mercury (planet) Mercury is the smallest and innermost planet in the Solar System. Its orbital period around the Sun of 87.97 days is the shortest of all the planets in the Solar System. It is named after the Roman deity Mercury, the messenger of the gods. Like Venus, Mercury orbits the Sun within Earth's orbit as an "inferior planet", and never exceeds 28° away from the Sun. When viewed from Earth, this proximity to the Sun means the planet can only be seen near the western or eastern horizon during the early evening or early morning. At this time it
Vulcan (hypothetical planet) Rochester, New York, both claimed to have seen a Vulcan-type planet close to the Sun. Watson, observing from Separation, Wyoming, placed the planet about 2.5 degrees southwest of the Sun and estimated its magnitude at 4.5. Swift, who was observing the eclipse from a location near Denver, Colorado, saw what he took to be an intra-mercurial planet about 3 degrees southwest of the Sun. He estimated its brightness to be the same as that of Theta Cancri, a fifth-magnitude star which was also visible during totality, about six or seven minutes from the "planet". Theta Cancri and the planet were