- The closest → planet to the
→ Sun and one of five planets visible with the
naked eye. The → greatest elongation
of Mercury is about 28°,
making it visible at most about 112 minutes after sunset or before sunrise.
It lies at a mean distance of about 0.39
→ astronomical units from the Sun.
Mercury is just 4,879 km in diameter, about 2.6 times smaller than
the Earth. Its → orbital period is 87.97 Earth days.
Mercury has a high → density, 5.4 g cm-3,
with only the Earth having a higher density among the planets. This is largely due to
Mercury being composed mainly of heavy metals and rock.
One → solar day on Mercury lasts the equivalent of 176
Earth days while the sidereal day (the time for 1 rotation in relation to
a fixed point) lasts 59 Earth days. Mercury is nearly
→ tidally locked to the Sun and over time
this has slowed the rotation of the planet to almost match
its orbit around the Sun. Mercury also has the highest orbital
→ eccentricity of all the planets with its distance
from the Sun ranging from 46 to 70 million km. Mercury has just 38% the
→ gravity of Earth, this is too little to maintain
an atmosphere against → solar winds, which blow it away.
The surface of Mercury which faces the Sun has
temperatures of up to 427°C, whilst on the alternate side this can be
as low as -173°C. Mercury’s core has more iron than any other planet in the
→ solar system. This has to do with its formation and early
life. If the planet formed quickly, increasing temperatures of the
evolving Sun could have vaporized much of the existing surface,
leaving only a thin shell.
- (lower case): Metallic chemical element, also called quicksilver;
symbol Hg (from L. hydrargyrum “liquid silver”).
→ Atomic number 80; → atomic weight
200.59; → melting point -38.842°C;
→ boiling point 356.58°C. Mercury was first recognized as
a chemical element (in the
modern sense) by the French chemist Antoine L. Lavoisier (1743-1794).
Etymology (EN): From L. Mercurius “Mercury,” the Roman
god, originally a god of tradesmen and thieves, from merx
“merchandise.”
Etymology (PE): 1) Mid.Pers. Tîr the name
of the planet Mercury, O.Pers. proper noun *Tira-dāta-
“given by Tir” (Hellenized Tiridates),
Mid.Pers. Tîr.dât the name of three Parthian Kings; Av.
Tīro.nakaθwa-.
2) Jivé, variant
živé, from Mid.Pers. zivik, zivandag “alive,
living,” from zivastan “to live,” zivižn “life;”
O.Pers./Av. gay- “to live,” Av. gaya- “life,”
gaeθâ- “being, world, mankind,” jivya-, jva-
“aliving, alive;” cf. Skt. jiva- “alive, living;”
Gk. bios “life;” L. vivus “living, alive,” vita
“life;” O.E. cwic “alive;” E. quick; Lith. gyvas
“living, alive;” PIE base *gweie- “to live.”
Simâb
“liquid silver,” from sim “silver” (Mid.Pers. âsīm)
