Mercury is the smallest planet in the solar system and is also closest to the Sun once every 88 days. Brightness of the planet is in the range between -2 to 5.5 in apparent magnitude, but not easily seen because of the small angular separation from the Sun (the most distant range of 28.3 degrees. It can only be seen in morning or evening twilight. Not so much known about Mercury because only one spacecraft to approach the Mariner 10 in 1974 to 1975. Mariner 10 only managed to map about 40 to 45 percent of the planet's surface.
Similar to the Moon, Mercury has many craters and also has no natural satellites and the atmosphere. Mercury has an iron core that creates a magnetic field with a strength of 0.1% of Earth's magnetic field strength. Mercury's surface temperature ranged from 90 to 700 Kelvin (-180 to 430 degrees Celsius).
Recorded observation of Mercury's earliest start time of the Sumerians in the third millennium BC. The Romans named the planet with the name of one of their gods, Mercury (also known as Hermes in Greek mythology and Nabu in Babylonian mythology).Astronomical symbol for Mercury is the abstraction of the head of the god Mercury with winged caps on the caduceus. The Greeks in the days of Hesiod named the Mercury Stilbon and Hermaon due before the fifth century BC they thought that Mercury was two different space objects, which one looks only at the time of sunrise and the other one looks just at sunset. In India, Mercury was named Budha (बुध), son of Candra, the moon. In Chinese culture, Korea, Japan and Vietnam, Mercury called "Save Water". The Hebrews called it Kokhav Hamah (כוכב חמה), "star of the hot" ("hot" means the Sun). Mercury's diameter 40% smaller than the Earth (4879.4 km), and 40% larger than the Moon. The size is also smaller (though more dense) than the satellites of Jupiter, Ganymede and Saturn's satellite, Titan.
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With a diameter of 4879 km at the equator, the planet Mercury is the smallest of the four terrestrial planets in the Solar System. Mercury is a metal composed of 70% and 30% silicate and has a density of 5.43 g/cm3 density is only slightly below the Earth. However, if the effect of gravity is calculated from the pressure of the Mercury is more dense than the Earth with no uncompressed density of 5.3 g/cm3 Mercury and the Earth is only 4.4 g/cm3.
Mercury is used to infer the density structure of it. High density of the Earth created by the pressure of gravity, especially in the core.Mercury but much smaller and the interior of the earth so that there is not such a high density because the planet is thought to have a large nucleus and rich in iron. Experts estimate that Mercury's core earth occupies 42% of its volume (Earth's core occupies only 17% of the volume of the Earth). According to recent research, most likely of Mercury's core is molten.
600 km thick mantle surrounding the core of Mercury and Mercury's crust as thick as expected 100 to 200 km. Mercury's surface has many skinny hills, some hundreds of kilometers in length.Presumably these hills formed as Mercury's core and mantle cooled and contracted at the time the crust was petrified.
Mercury contains more iron than any other planet in the solar system and several theories have been proposed to explain it. The most widely accepted theory is that Mercury originally had a metal-silicate ratio similar to a meteor Kondrit generally and has a mass about 2.25 times the present mass. But in the early solar system history, Mercury was hit by a planetesimal size about one-sixth of its mass.The impact has been releasing most of the original Mercury's crust and mantle, and left the core. The same process has also been proposed to explain the creation of the Moon.
Another theory states that Mercury may have formed from the solar nebula before the Sun has been stable energy output. Mercury originally had two times the current mass, but with mengambangnya protomatahari, the temperature around the mercury could reach about 2500 to 3500 Kelvin and may reach 10 000 Kelvin. Much of Mercury's surface will evaporate at a temperature such that, create an atmosphere of "rock vapor" which may be blown by the solar wind.
The third theory proposes that resulted in the pull on the particles from which Mercury will be formed so that the lighter particles of matter pengimbuhan missing. Each of these theories predicts a different surface composition. Two future space missions, MESSENGER and BepiColombo will test these theories.
