Mercury (planet)

Mercury (or Sol I) was the first planet of the Sol system.

History
In 1969, the USS Enterprise (NCC-1701) passed Mercury as it attempted a slingshot effect around Sol in an effort at returning to 2267. When the Enterprise passed this innermost planet, the gravitational pull of the star increased. 

In 2254, Mercury was seen on a map depicting the inner Sol system. This map was scanned by the Talosians. 

Three years later, Mercury was seen on a chart depicting the Sol system. This map was scanned by Nomad. 

Mercury was featured in an amusing story a holographic Doctor Stephen Hawking told his holographic poker partners Albert Einstein and Sir Isaac Newton and Data. He said that "in that frame of reference the perihelion of Mercury would have precessed in the opposite direction!" Albert Einstein found this "a great story"; Sir Isaac Newton, however, did not understand the joke. 

In the The Adventures of Captain Proton holoprogram series, Mercury was controlled by Doctor Chaotica. When he tried to conquer Earth, he claimed that those who oppose him "will face a dire fate as slaves in the mines of Mercury."