The planet Mercury was named after the Roman god of the same name. Mercury was likely named this due to it having the fastest cycle around the sun. Mercury was first discovered sometime around the same time the Sumerians were around.
The Measurements of Mercury
The distance from Mercury to the sun is 48 million miles (77 million kilometers) or a half of an AU. The density of Mercury is 5.427 cm³ which is 98% of the density of Earth. Mercurys diameter is 3032 miles (4879 kilometers).
Time and weather related details
Mercury is the closest planet to the sun which causes it to at times be either extremely hot or extremely cold due to the planet not having an atmosphere to retain heat. As an example of this tempatures can be anywhere from 800 degrees Fahrenheit to -280 degrees Fahrenheit.
Various other Information
Mercury unlike most planets does not have any moons. The period of rotation for mercury is 59 days while a full revolution lasts 88 days. The gravity of Mercury is weaker than Earths adding up to only a third of Earths total gravity. Mercury consists of mostly metal solids known as amalgams. Mercury consists of mainly flatland and craters although there are a few volcanoes scattered around. At the current time of writing this there have been no recent expeditions to Mercury. However both the MESSANGER and Mariner 10 have explored and taken images of Mercury.