Named by the Romans, Mercury is the smallest and innermost planet of our solar system. The plant was named such for its rapid orbit around the sun – approximately 88 days – moving with the speed that Mercury (the Roman equivalent of Hermes, messenger of the gods) moved in mythology.

 

Being so close to the sun, the planet can reach up to 800 degrees Fahrenheit but drop to -290 degrees at night due to the planet’s lack of atmosphere. Likewise, its nearness to the sun makes Mercury difficult to observe from Earth except during twilight.

 

Mercury’s surface most resembles the Earth’s moon, as it has a number of craters from meteoroids and comets and stretches of flat terrain. The planet is the second densest planet in the solar system after Earth, with a molten core.

 

NASA has studied the tiny planet a few times. The Mariner 10 mission mapped about 45 percent of the planet’s surface in the 1970s, while the more recent MESSENGER mission has been in orbit around Mercury since March 2011.