Mercury means:
In astronomy mythology, Mercury was the Roman version of the god Hermes. He was the messenger for the other gods, and for this reason Mercury is often depicted in pictures with winged sandals. In addition to delivering messages, he was also the protector of travelers, and merchants (KidsAstronomy.com).
Mercury is the planet closest to the sun, due to this it is able to travel around the sun faster then any other planet. It is the second smallest planet in our solar system, it is comparable to the size of our moon.
It has a very thin atmosphere, which is not suitable for human life. Mercury's surface has holes in it where meteorites, asteroids, etc have crashed into it. The days on Mercury are so hot that a person could burn to death and the nights on mercury are so cold that a person could freeze to death.
Mercury spins/ routes so slowly that each Mercury day is equal to 176 Earth days. On the other hand its closeness to the sun allows it orbit quickly, one year is equal to 88 Earth days.
Fun Mercury Facts:
Mercury is so close to the Sun, and so small, that it has only a very small atmosphere. It has been blown away by the Sun's solar winds. That means that there is almost no air on Mercury (KidsAstronomy.com)
Mercury is hard planet to study for many reasons, but scientists continue to find out what they can but about this mysterious planet.
For more information check out:
http://www.happynews.com/living/space/mercury-information-kids.htm
http://www.kidsastronomy.com/mercury.htm
