Mercury is the nearest planet to the Sun. It is the second-smallest planet in the Solar System after Pluto. Mercury is not well known, only one spacecraft, the NASA Mariner 10 could see 40 % of the surface of the planet. As far as we know, Mercury looks like the moon, it has no atmosphere and is heavily cratered, furthermore, it has no satellite. Mercury has an iron kernel and its magnetic field is 1% as strong as the Earth’s one. Temperatures on the surface vary from -180°C to +430°C, the mean is around 178.8°C. Its great difference is due to the absence of atmosphere. Mercury is a planet of iron, the principal compound of the kernel which represent more than 50% of the volume. Another particularity of Mercury is its variation in its distance from the sun which varies from 46,000,000 to 70,000,000 km. Only Pluto has a greater variation. 
Mercury is the messenger of god for the Romans and Greeks, the planet of Water for the Chinese. Its symbol is a Venus with wings. The Greeks believed that Mercury was a two planets system (Apollo during the night and Hermes during the day). Mercury was known by Sumerians (3000 B.C) and Babylonians as well. Mercury represents the principles of mentality, thinking patterns, rationality, transport, reasoning, and communication. It influences the intellect. In Vedic astrology, Mercury is the son of the moon, it is a neutral planet and its influence depends in function of its place in the sky. Mercury is related to education, writers, businessmen and scientists. In the body, Mercury rules over the intestines, lungs, arms, ear hearing system, and the nervous system.
The future will show us more information about Mercury which have been subject of lots of speculation. During the past, for example, calculations didn’t match with Newton theories. We needed to wait Einstein theory of relativity to explain the difference between reality and old theory. Mercury has been suggested as one possible target for space colonization of the inner solar system, along with Mars, Venus, the Moon and the asteroid belt. Two operations are being set for Mercury exploration: One European and Japanese one and one American around 2012. Mercury is difficult to attain cause of its proximity to the Sun, spacecrafts must fight against the Sun gravitation which is quite powerful near Mercury. A lot of news will come.