mecury

There are people, of course, who made serious probes and discoveries regarding the planet. The Greeks, seeing the planet during the morning and evening sky, had a name for it. It was called Apollo during the morning and Hermes at night. However, they did not know the two stars were actually just one object. It was later during the 4th century that the Greeks discovered that Apollo and Hermes were the same.
Mercury is the closest planet to the Sun and due to its proximity it is not easily seen except during twilight. For every two orbits of the Sun, Mercury completes three rotations about its axis and up until 1965 it was thought that the same side of Mercury constantly faced the Sun. its surface is heavily cratered and very old; it has no plate tectonics. On the other hand, Mercury is much denser than the Moon (5.43 gm/cm3 vs 3.34). Mercury is the second
densest major body in the solar system, after Earth. Actually Earth's density is due in part to gravitational compression; if not for this, Mercury would be denser than Earth. This indicates that Mercury's dense iron core is relatively larger than Earth's, probably comprising the majority of the planet. Mercury therefore has only a relatively thin silicate mantle and crust.
     Mercury has no atmosphere, it rather possesses a thin exosphere made up of atoms blasted off its surface by solar wind and striking micrometeoroids. Because of the planet's extreme surface temperature, the atoms quickly escape into space. With the thin exosphere, there has been no wind erosion of the surface and meteorites do not burn up due to friction as they do in other planetary atmospheres.

Planet Profile

Mass: 330,104,000,000,000 billion kg (0.055 x Earth)
Equatorial Diameter: 4,879
Polar Diameter: 4,879
Equatorial Circumference: 15,329 km
Known Moons: none
Notable Moons: none
Orbit Distance: 57,909,227 km (0.39 AU)
Orbit Period: 87.97 Earth days
Surface Temperature: -173 to 427°C
First Record: 14th century BC
Recorded By: Assyrian astronomers
A day, from sunrise to sunrise, on Mercury is equivalent to 176 Earth Days. 

transit of Mercury
Thirteen times a century Mercury can be observed from the Earth passing across the face of the Sun in an event called a transit,These rare transits fall within several days of May 8 and November 10, the last three transits occurred in 1999, 2003 and 2006 the next will occur on the 9th May 2016. A transit of Mercury across the Sun takes place when the planet Mercury comes between the Sun and the Earth, and Mercury is seen as a small black dot moving across the face of the Sun.


 Mercury is the closest planet to the sun, yet it is not the hottest planet.  How is this possible?

Mercury's low mass and close proximity to the sun keep it from having anything but the thinnest of atmospheres, and this is the reason it must pass on being the hottest planet. An atmosphere helps to cloak a planet, keeping heat from leaking into space and balancing it, to some degree. Without an atmosphere, Mercury loses a great deal of heat into space, rather than sharing with its night side.


Orbiting between 28 and 43 million miles (46 and 70 million kilometers) from the sun, Mercury, also the smallest planet, feels the brunt of the solar rays. The planet has an average temperature of 332 degrees Fahrenheit (167 degrees Celsius) The day side of the planet reaches temperatures of up to 801 F (427 degrees C). In contrast, the chilly night side can get as cold as minus 279 F (minus 173 C).
    The hottest planet, incidentally, is Venus, the second body from the sun. Venus has a thick atmosphere that blankets the planet, keeping its temperature at an average of 864 F (462 C).
 

Apollo or Hermes ?

Since Mercury was visible from the Earth, we wouldnt know who discovered the planet.
 There are people, of course, who made serious probes and discoveries regarding the planet. The Greeks, seeing the planet during the morning and evening sky, had a name for it. It was called Apollo during the morning and Hermes at night. However, they did not know the two stars were actually just one object. It was later during the 4th century that the Greeks discovered that Apollo and Hermes were the same.