Surface, Mars And Gravity Of Mercury:
Mercury is a heavily cratered planet and its surfaced is similar to the surface of Earth’s Moon catering on Mercury triggered a Volcanic eruptions that filled much of the surrounding area. Mercury does have a magnetic field (probably generated by a partly liquid iron-core).
Mercury’s mass is about 3.3x10 kg. This is about 1/20th of the mass of the gravity of the Earth.
Atmosphere:
Mercury thin atmosphere consists of trace of hydrogen and helium. Since the atmosphere is so slight, the sky would appear pitch black (except for the sun, stars and other planets when visible) even during the day. Also there is no “Greenhouse Effect” on Mercury. When the sun sets, the temperature drops very quickly, since the atmosphere does not help retain the heat. Unlike Earth, Mercury has no Moons.
Temperature Range:
Mercury has a huge range in temperatures. Its surface ranges in temperatures from 270* F to 800* F (- 168*c to 427*c). During the very long daytime (88-Earth days long), the temperatures are very high (the second highest in the solar system only. Venus is hotter than Mercury. During the long night the thin atmosphere lets the heat dissipate and the temperature drops quickly
Length Of A Day And Year On Mercury:
Mercury revolves around the sun very quickly, but rotates around its axis very slowly. One day on Mercury (sunrise to sunrise) is longer than one year on Mercury (one orbit around the sun).
Mercurian Year:
A year on Mercury takes 87.97 Earth days; it takes 87.97 Earth days for Mercury to orbit the sun once.
Mercurian Sidereal Day:
Each sidereal day on Mercury takes 58.65 Earth days. It takes Mercury 58.65 days (2/3’s of its year) to rotate around its axis once. One day on Mercury seems to last two Mercurian years (or 176 Earth days) i.e. sunrise to sunrise. It is daytime for one Mercurian year, and nighttime for one Mercurian year.
Inside Mercury:
Crust:
Mercury has a thick crust that is composed mostly of silicate rocks. Mercury may have small ice caps at its north and south poles; this ice stays frozen inside deep craters that are shaded from sunlight.
Mantle:
Beneath the crust it is a mantle (also made of silicate rocks) that is hundreds of kilometres thick.
Core:
At the centre of Mercury is a partly molten iron core about 2,300 miles (7,500 km) in diameter (almost half of the diameter of Mercury). This core accounts for about 80% of Mercury’s mass. This core generates a magnetic field (which is how we know that Mercury has an iron core).
Density:
Mercury has a density of 5,430 kg/m, slightly less than that of the Earth. Mercury is the second densest planet in the solar system (after Earth) because of its large iron core. Mercury is a heavily cratered planet. Cratering on Mercury triggered volcanic eruptions that filled much of the surrounding area. The largest crater on Mercury is the Caloris Basin, which is 800 miles (1,300 km) across and may have been formes by Asteroid hitting Mercury. Many craters on Mercury have been named for writers, musicians, painters, and other artists.e.g. Beethoven, Shelly, Michelangelo etc.
There are also areas of relatively flat planes on Mercury; these are called Planitas. Lines of mountainous cliffs, rupes scar the surface of Mercury. These long lines were probably formed when the planet cooled about 4 billion years ago, causing these cracks to form.
Spacecraft Visits:
Mercury was visited by NASA’S MARINER 10 in 1973 and 1974 and its surface was mapped by this spacecraft.
