Mercury, named after the Roman deity of finance and commerce, it is the closest and smallest planet to the sun. Being the closest to the sun, the star’s gravitational force is the strongest compared to the other plainest. So that Mercury does not fall into the sun, it orbit must rotate faster than the other planets; thus, Mercury speeds around the sun at a rate of 88 Earth days.
Mercury’s distance from the sun is .307 AU (average) and its surface temperature can range from 800 °F during the day to −280 °F at night. It rotates three times for every two revolutions around the sun. Mercury has no atmosphere and has no moons.
The planet has a great degree of craters that somewhat replicate the moon’s craters and this information helps scientists determine that this humanly inhabitable planet has been in this state for billions of years.
Any advanced creature that would live on Mercury would most likely have extremely large lungs to compensate for the atmosphere or to an opposite extent, have lungs that equate to fish. The creature would probably have a sort of skin that can accommodate very hot weather and very cold weather in one Mercurian day. Their eyes would be extremely small, since being so close to the sun would cast an immense brightness, similar to being on the beach or on white snow on a bright sunny day, but much more intense and their adaptable skin would most likely contain some type of protective coating to avoid sun burn.
It is difficult to see Mercury from Earth, due to its closeness to the sun. Humans have attempted to visit Mercury and two successful orbits were made by Mariner 10 and the MESSENGER spacecraft. Unfortunately, there were no signs of large lung creatures roaming about.