Other Information
If you look to the left, that is the Mariner 10 space probe that was that the first one to travel to Mercury and orbit it to take pictures and get some valuable info on Mercury. Mariner 10 took pictures of about 45 percent of Mercury's surface. In 1991 astonomers used radar observations to find out that their could be water ice inside Mercury and that the craters are really cold. They think that meterorites might have brought ice to these places of the planet or water vapor might have pushed the gasses out and frozen itself inside Mercury.