Mercury
Mercury is the first and smallest planet of our Solar System. Its orbit around the Sun takes only 88 days, while a complete rotation around itself takes place in 59 days. Due to the close distance to the Sun, the temperature of Mercury reaches 426 °C, while at night the temperature reaches -180 °C. This fact happens because of the lack of atmosphere.
Mercury has got a large solid iron core that occupies over the half of the volume of the planet while outside the core there are fluid sulfur compounds. In 1974 the space mission Mariner 10 gave us the first information about Mercury as well as the first images of its surface. Its surface is similar to the surface of the Moon, full of craters and "seas", so it is obvious that Mercury had an intense geological past. Furthermore, a bipolar magnetic field, similar to Earth magnetic field, was observed, but much weaker. That fact was confirmed in 2011 by the MESSENGER mission.
