Mercury is the closest Planet to the solar system and is one of the five classical planets visible with the naked eye and is named after the swift-footed Roman messenger god.
It is not known exactly when the planet was first discovered - although it was first observed through telescopes in the
seventeenth century by astronomers Galileo Galilei and Thomas Harriot.
Mercury is also known as the World of extremes
Only two spacecraft, both robotic and launched by NASA, have visited Mercury so far, making it the least explored terrestrial planet.
Mariner 10 launched in 1973 and imaged around 45% of the planet's surface from 1974 until its end of mission in March 1975.
MESSENGER was launched in 2004 and entered Mercury's orbit in 2011, making it the first spacecraft to do so. This mission lasted for four years before the probe succumbed to the planet's gravity and impacted its surface in 2015. It collected extensive data and images and transmitted them back to Earth to be studied by scientists.
BepiColombo is a joint space mission by the European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA), currently proposed to be launched in 2018, with the aim to reach Mercury in December 2025.
The planet is terrestrial, meaning that it has a solid surface and is mainly made of silicate rocks or metals. The planet Mercury is mainly made up of iron.
Mercury is a terrestrial planet, like like all of the 4 inner planets: Mercury, Venus, Earth and Mars. It’s the smallest of them, and has a diameter of only 4,879 km at its equator. What is the composition of Mercury?
Astronomers have estimated that the Mercury composition is made up of approximately 70% metals and 30% silicate material. In fact, it’s only slightly less dense than the Earth, with 5.43 g/cm3.
Since Mercury is smaller than Earth, its gravity doesn’t compress it down as much, so it actually has much more heavier elements inside it. Geologists estimate that its core is very large, and mostly iron. The core probably accounts to 42% of Mercury’s volume, while Earth is just 17%.
In appearance it is similar to Earth's Moon.
Mercury has big craters just like Earth's Moon. It has craters as big as the country France and It's weather and climatic conditions is going to make new craters on it's surface.
Mercury has little atmosphere, but what it does have is made up mostly of oxygen, sodium, hydrogen, helium and potassium.
The thin atmosphere, or exosphere, does little to prevent or slow down impacts from extraterrestrial objects, leaving the surface littered with craters.
Thanks to the nearby Sun, Mercury’s surface temperatures reach 430 degrees Celsius (800 degrees Fahrenheit) — yet like our Moon, water ice exists inside permanently shadowed craters at the poles.
Mercury is particularly interesting to scientists who study exoplanets, planets that orbit other stars. Thousands of known exoplanets orbit extremely close to their stars. By studying Mercury right here in our backyard, we can better understand what these close-orbiting worlds might be like.
Mercury has no moons. The planet's close proximity to the Sun makes having moons impossible, as the star's strong gravitational pull would likely pull them out of the planet's orbit.
Days on Mercury are very long because the planet rotates very slowly. One day-long spin lasts for 59 Earth days. But because of its fast orbit, one Mercury year takes 88 Earth days. This means that two years on Mercury lasts for only three days.
The planet's sunrise would be unusual to us on Earth. Due to its elongated orbit and slow rotation, from some places on Mercury's surface, the Sun appears to rise briefly before setting and rising again. At sunset, the reverse happens, with the Sun appearing to set twice.
The planet spins almost vertically on its axis, so its poles are never fully sunlit. The lack of tilt also means that the planet does not experience yearly seasons like Earth.