Facts About The Planet Mercury

- Diameter: 4,878 km (3,032 miles) at its equator, which is about two - fifths of Earth's diameter.

- Temperature: ?

- Orbit: 57,910,000 km (0.38 AU) from Sun. Orbiting the Sun once every 88 days.

- Average Distance: About 58 million km (36 million miles)

- Time to Rotate: 58.6 days

- Mass: 3.30e23 kg (5.5% of Earth)

- Moons: 0

- Period of Rotations: 58.6462 days.

Orbit: Mercury has a very elliptical (oval shaped) orbit.  At perihelion (at its closest point) it is about 46 million km (28.58 miles) from the sun, but at aphelion (at its farthest point) it is about 70 million km. Mercury is about 77.3 million km (48 miles) 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 48 km (30 miles) per second and it takes 88 Earth days to orbit the Sun. The Earth goes around the Sun once every 365 days.

Rotation: The planet rotates once about every 59 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 176 Earth days (interval between one sunrise and next).

Composition: Mercury is the second densest major body in the solar system after Planet Earth and its density is slightly less than 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 100 pounds on earth would weigh only about 38 pounds on Mercury.

Mercury has a large iron core which is most likely at partially molten and generates a magnetic field about 1% as strong as that of Earth’s. Mercury’s interior appears to resemble that of Earth. Both planets have a rocky layer called mantle beneath their crust and both planets have an iron core.

Surface: The surface of Mercury consists of cratered terrain and smooth plains and many deep craters formed when meteors or small comets crashed into the planet. The largest known crater is Caloris Basin, with a diameter of 1300 km (800 miles). Like 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 moon. It reflects approximately 6 percent of the sunlight it receives. Like the moon, Mercury is covered be a thin layer of minerals called silicates in form of tiny particles.

Water: Scans of Mercury made by Earth- based radar indicate that crates 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.

Temperature:  Mercury is planet of extreme temperature variations. It is hotter than Venus, but with less fluctuations. The temperature on planet may reach up to 450 degree C during the day. But at night, the temperature may drop as low as -170 degrees C. the sunlight on Mercury’s surface is 6.5 times as intense as it is on Earth due its closeness to the Sun.

Atmosphere: Mercury is dry, extremely hot and almost airless. Planet Mercury is too small for its gravity to retain any significant atmosphere over long periods of time. The weak atmosphere contains hydrogen, helium, oxygen, sodium, calcium and potassium.

Due to the heat of the planet, the very thin atmosphere is blasted off its surface by the solar wind and quickly escapes into space. Mercury’s atmosphere is constantly being replenished. Mercury does not have enough atmosphere to slow down meteoroids and burn them up by the friction. The Sun’s are approximately 7 times stronger on Mercury than Earth. The Sun also appears about 21/2 times as large in Mercury’s sky as in Earth’s.

Name: The Greeks gave it two names: Apollo for when It came as morning star and Hermes when it came as an evening star. In Roman mythology, Mercury is the God of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes the messenger of god. The planet probably received this name because it moves so quickly across the sky.

Life: The plant and animal life of the Earth could not live on Mercury because of the lack of oxygen and the intense heat. Scientist doubts that the planet has any form of life.

Viewing: Because of Mercury’s size and nearness to the Sun, the planet is often hard to be seen from the Earth without a telescope. Mercury can be seen low in the western sky just after the sunset. At other times, it can be seen low in the eastern sky just before sunrise.

Phases: When viewed through a telescope, Mercury can be seen going through ‘changes’ in shape and size. These apparent changes are called phases and resembles those of the moo. They result from different parts of Mercury’s sunlit side being visible from Earth at different times.

History: Mercury has been known since ancient times. Until the mid- 1960’s, astronomers believed that Mercury rotated once every 88 Earth days, the same time planet takes to go round the Sun. if Mercury did this, one side of the planet would always face the Sun and the other side would always be dark. However, radar studies conducted in 1965 showed that the planet rotates once in about 59 days.

The only space craft to come close to Mercury was Mariner 10 from 1974 to 1975, which was only able to map 40%- 45% of the planet’s surface.
For more information about Mercury and other Planets, please visit: http://www.solarviews.com/eng/mercury.htm