Mercury Globe-MESSENGER mosaic centered at 0degN-0degE
Adjective(s) Mercurian, Hermian
Orbital properties
Aphelion/apoapsis 69,816,900 km

0.466 697 AU

Perihelion/periapsis 46,001,200 km

0.307 499 AU

Semi-major axis 57,909,050 km

0.387 098 AU

Orbital eccentricity 0.205 630
Orbital period 87.969 1 d

(0.240 846 a)
0.5 Mercury solar day

Average orbital speed 47.362 km/s
Physical properties
Radius 2439.7±1.0 km

0.3829 Earths

Mass 3.3022×1023 kg

0.055 Earths

Mean density 5.427 g/cm3
Escape velocity 4.25 km/s
Rotation period 58.646 d

1407.5 h

Average surface temperature min mean max

0°N, 0°W 100 K 340 K 700 K
85°N, 0°W 80 K 200 K 380 K

Apparent magnitude −2.6 to 5.7
Moons 0

Mercury is the planet closest to the Sun. It has no atmosphere, so it has a large temperature range. It is the smallest terrestrial planet in the solar system, it's so small, that Titan and Ganymede exceed it in size.


Like Venus, Mercury has no moons.


Mercury was discovered by ancient astronomers thousands of years ago. It was named after the Roman god of messengers, Mercury.

Exploration Edit

So far only two satellites have explored Mercury, Mariner 10, and MESSENGER.

Predicted FutureEdit

Along with Earth and Venus, in about 5 billion years, Mercury will be destroyed when the Sun turns into a Red Giant.


Statistic Name Statistic Calculation
Moons 0
Atmosphere None
Density 5.43 g/cm
Length of day 1400 hours


  • It has many craters on its surface because it doesn't have an atmosphere to stop asteroids from crashing into it.
  • Mercury is a terrestrial planet.


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