Mercury
Magnetospheric
Orbiter
MIO

MERCURY

The Moon's Look-Alike

With a surface covered in craters, Mercury closely resembles the Moon in appearance. However, terrain has also been discovered peculiar to Mercury and not seen on the Moon. Many mysteries remain as to how this was created.

Mercury
Moon
Moon:NASA/Goddard/Lunar Reconnaissance Orbiter

600 Temperature Difference
between Day and Night

Mercury is a planet with a very harsh environment. As the closest planet to the Sun, Mercury receives sunlight ten times stronger than that on Earth. The surface temperature of Mercury reaches as much as 430 during the day. At night the temperature drops to about minus -170, because of heat escaping into space due to the lack of a thick atmosphere such as on Earth.

430~170
600 temperature difference
5004003002001000-100-200

NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Small but Dense Planet

Mercury is the smallest planet in the Solar System, with a size less than half that of the Earth. Despite its small size, the density of Mercury is roughly equal to that of the Earth and it is thought that the interior contains a huge iron core extending to three-quarters of the radius of the planet.

Mercury4,880km5.43g/cm3
Venus12,104km5.24g/cm3
Earth12,756km5.52g/cm3
Moon3,476km3.34g/cm3
Mars6,787km3.93g/cm3
DiameterDensity

Mars:NASA/JPL-Caltech/USGS Earth:NASA Moon:NASA/Goddard/Lunar Reconnaissance Orbiter

Magnetic Field like Earth

Mercury also possesses a magnetic field with a strength of around 1/100th of that of the Earth's. A flowing liquid inner core is necessary for a planet to generate a magnetic field. Why Mercury, the smallest and easiest planet to cool and solidify, still has a magnetic field is a great mystery.

Core
Magnetic equator

Fundamental parameters

Mercury
Average
orbital radius
0.39 AU
Rotation
period
~55 days
Revolution
period
~88 days
One day
period
~176 days
Parameter
Average
orbital radius
Rotation
period
Revolution
period
One day
period
Earth
Average
orbital radius
1 AU
Rotation
period
~24 hours
Revolution
period
~365 days
One day
period
~24 hours
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