In Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods.
The planet probably received this name because it moves so quickly across the sky.
Observation Records
Mercury has been visited by only one spacecraft, Mariner 10.
Properties:
Mercury's orbit is highly eccentric;
at perihelion it is only 46 million km from the Sun but at aphelion it
is 70 million.
Mercury is the only body in
the solar system known to have an orbital/rotational resonance with a ratio
other than 1:1.
Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K. Mercury is heavily cratered and it has no atmosphere; it exhibits no plate tectonics.
Mercury is has density 5.43 gm/cm3.
Mercury's dense iron core is relatively larger than Earth's, and has only a relatively thin silicate mantle and crust.
One of the largest features
on Mercury's surface is the Caloris Basin ;it is about 1300 km in diameter.
Amazingly, radar observations
of Mercury's north pole show evidence of water ice in some craters.
Mercury has a small magnetic field whose strength is about 1% of Earth's.
Mercury has no known satellites.
Mercury
Statistics
Mass (kg) ----------------------------------------------------------------------
3.303 x 1023
Mass (Earth = 1) ---------------------------------------------------------------
5.5271 x 10-02
Equatorial radius (km) ----------------------------------------------------------
2,439.7
Equatorial radius (Earth = 1) ----------------------------------------------------
3.8252 x 10-01
Mean density (gm/cm3) ---------------------------------------------------------
5.42
Mean distance from the Sun (km) -----------------------------------------------
57,910,000
Mean distance from the Sun (Earth = 1)
----------------------------------------- 0.3871
Rotational period (days) ---------------------------------------------------------
58.6462
Orbital period (days) ------------------------------------------------------------
87.969
Mean orbital velocity (km/sec) ---------------------------------------------------
47.88
Orbital eccentricity --------------------------------------------------------------
0.2056
Tilt of axis (degrees) -------------------------------------------------------------
0.00
Orbital inclination (degrees) ------------------------------------------------------
7.004
Equatorial surface gravity (m/sec2)
----------------------------------------------- 2.78
Equatorial escape velocity (km/sec) ----------------------------------------------
4.25
Visual geometric albedo ----------------------------------------------------------
0.10
Magnitude (Vo) ------------------------------------------------------------------
-1.9
Mean surface temperature --------------------------------------------------------
179°C
Maximum surface temperature ----------------------------------------------------
427°C
Minimum surface temperature -----------------------------------------------------
-173°C