The early records about Mercury can be found in the Babylonian and Sumerian writings, about 3000 years ago. The planet is also mentioned in Ancient China, India, and in the documents laying in the tombs of Egypt. Mercury has and still is hard to see because it does not orbit far from the Sun. This problem was also encountered by the ancient astronomers.
Ancient Greeks called Mercury either Apollo or Hermes. Its present name was given by the Romans, due to the fact that Mercury moves fast before the dawn and after the sunset.
In the recent history, Mercury is believedto be first observed by Johann Hieronymus. He drew the surface of Mercury and kept a record of it in his notes. Schroeteralso studied the planet, until his death in 1816. Moreover, Mercury was observed by Percival Lowell and Schia too, whonoticed dark streaks on Mercury's surface. They thought those were the same canals seen on planet Mars but with the use of a more advanced telescope, EugeniosAntoniadi was later able to map out the surface of Mercury. From his notes, it has been discovered that these so-called Martian canals were just an optical illusion. In present,Mercury images comes from Mariner 10, the first robot that photographed our closest and smallest planet.
Because Mercury is so close to the Sun, there is no atmosphere.
Mercury is 4879 (km) across. That makes Mercury just less than half the size of the Earth.
Mercury has craters like those on the Earth's moon. The largest crater on Mercury is Caloris Basin. It is about 1300 km wide. It was created by a huge asteroid which hit Mercury. The asteroid was probably 100 km wide.
The surface also has big cliffs called scarps. They were created when Mercury cooled down. It shrank, causing the surface to get wrinkled in some places. This wrinkling created the scarps.
There may also be ice at the poles of Mercury because there the temperature is much lower.
Mercury gets very hot during the day and very cold at night. It is very hot during the day (over 400°C) because Mercury is so close to the Sun. At night, however, Mercury loses almost all its heat because there is almost no atmosphere to keep it there. The temperature can fall to almost -200°C.
Mercury rotates around his axes much more slowlier than the Earth, so one day on Mercury lasts as long as 58 days on Earth!
Mercury has the shortest year in the Solar System. It is about 88 Earth days long.
As far as we know, the center of Mercury is made of iron. It contains more iron for its size than any other planet in the Solar System. The rest of Mercury is made of rock.