Mercury

Mercury has a very elliptical oval shaped orbit. At perihelion at its closest point it is about million from the Sun, but at aphelion at its farthest point it is . Mercury is about million from Earth at its closest approach. Mercury is not easily seen from Earth due to its small angular separation from the Sun. Mercury moves around the sun faster than any other planet. Mercury travels about miles per second and it takes Earth days to orbit the sun. The Earth goes around the sun once every.

The planet rotates once about every Earth days, a rotation slower than that of any other planet except Venus. As a result of the planet's slow rotation on its axis and rapid movement around the sun, a day on Mercury lasts Earth days interval between one sunrise and the next. Mercury is the second densest major body in the solar system after Planet Earth and its density is slightly less than the Earths. Mercury's smaller mass makes its force of gravity only about a third as strong as that of the Earth. An object that weighs pounds on the Earth would weigh only about pounds on Mercury.

Mercury has a large iron core which is most likely at least partially molten and generates a magnetic field about as strong as that of Earth's. Mercury's interior appears to resemble that of the Earth. Both planets have a rocky layer called a mantle beneath their crust and both planets have an iron core.The surface of Mercury consists of cratered terrain and smooth plains and many deep craters similar to those on the moon. The craters formed when meteors or small comets crashed into the planet. The largest known crater is Caloris Basin, with a diameter.

Like the other terrestrial planets Venus, Earth and Mars Mercury is made mostly of rock and metal. Mercury's surface appears to be much like that of the moon. It reflects approximately percent of the sunlight it receives, about the same as the moon's surface reflects. Like the moon, Mercury is covered by a thin layer of minerals called silicates in the form of tiny particles. Scans of Mercury made by Earth-based radar indicate that craters at Mercury's poles contain water ice. The floors of the craters are permanently shielded from sunlight, so the temperature never gets high enough to melt the ice.