The Mercury is the innermost planet from the Sun in sequence of all planets in our solar system. The mercury is the smallest and closest planet to the sun. The size of the mercury is slight bigger than the Earth’s moon. The Sun is visible three times larger from mercury than appears from the earth. Though mercury is closest to the sun it is not hottest planet in our solar system.
Properties of Mercury
- Mercury is the closest planet to the sun and smallest planet in solar system.
- Mercury name was given by roman deity mercury.
- Average diameter of mercury is 4879.4 km.
- Mass of mercury is 0.33 X 1024kg and density is 5.427 gm/cm3.
- It has no any natural satellite.
- Mercury does not orbit the sun in perfect circular path. Its perihelion is 4,60,01,200 km and aphelion is 6,98,16,900 km.
- One year of mercury is 87.97 days and one day is about 58 days 15hrs 30 min.
- Orbital inclination of mercury is 7oC to orbital plane of earth.
- Axial tilt of mercury is 0.027 degree.
- Orbital eccentricity of mercury is largest to all other planets in solar system.
- Mercury has wide temperature difference in day and night. Temperature in day is 427oC while at night -173oC but in polar area temperature remains constant as -93oC.
- Mercury is visible by unaided eye. It visible only just after sunset and just before sunrise.
Just like the Earth, Mercury is also rocky planet. Mercury has large molten Core which covers about 55% of its total volume. The core is 3600 km in diameter. Core is highest iron contents than any other planet in solar system. The core is surrounded by Mantle made of silicate having thickness 500-700 km. Outer most layer of mercury is Crust which is 35 km thick. The mercury has 70% metallic and 30% silicate material ratio which makes it second densest planet. Mercury has dark gray rocky surface with thick layer of dust.
Orbit and Rotation
In entire solar system, mercury is the only planet which orbits the sun at very fast rate. The mercury’s travelling rate in space is 47 kilometer with this speed it completes one revolution around the sun in 88 days. Its path around the sun is egg shaped and highly eccentric as closest distance from the sun is 47 million kms and farthest distance is 70 million kms. Due to varying in distance the tidal force of sun on mercury is very strong about 17 times stronger than moon’s tidal force on the earth.
The mercury completes one spin around its axis in 59 days. Due to slow axial rotation and very high rotation around the sun , just like other planets it is not accompanied sunset and sunrise in each rotation.
The mercury’s axial inclination is 0.027 degree. Orbital inclination of mercury is about 7 degree to plane of earth’s orbital path. Because of this, the movement of mercury can be seen on the face of the sun when it passes through earth’s orbital path and between the sun and the earth. This is occurred only on every seven years and mainly visible in May and November.
Surface of Mercury
Similar to moon’s surface, Mercury’s surface is also shown like plains and craters which were formed by heavy impact of comets and asteroids. Before 4.6 billion years at the time of formation of mercury and after that it was heavily bombarded by asteroids and comets over entire surface. During this time period planet was also volcanically active which created smooth plains on its surface like moon. As the core cooled and contracted the surface became wrinkled.
The craters on mercury are ranging from small to hundreds of kilometers in diameter. The largest basin filled with magma having diameter 1550 kms is “Caloris basin”. About 15 more basins are identified on surface of mercury.
Due to absence of atmosphere of mercury, the temperature on mercury’s surface varies from -173oC to 427oC. Although the temperature at day is very high, ice also present on mercury’s surface at polar area where in deep floor of craters where sunlight not reached and temperature remains always below -173oC.
The mercury has weak surface bounded exosphere. It is composed of hydrogen, helium, oxygen, sodium, calcium, potassium and other gases with pressure less than 0.5 nPa. This exosphere is not stable. Exosphere receives hydrogen and helium from solar wind.
Though mercury is small in size and slow rotation, magnetic field is very strong and about 1.1 times that of the earth. At equator magnetic field strength is 300nT. The magnetic field is generated by dynamo effect in metal core. Core creates strong magnetic field which is one percent stronger than the earth. The magnetic field of mercury is capable to defect the solar wind also to trap plasma of solar wind.
Visit to Mercury
Two spacecrafts have visited the mercury till date. First was Mariner 10 in 1974 and 1975. Mariner 10 visited three times the planet and discovered half surface of planet with thin atmosphere and magnetosphere. Second was Massenger which orbited in 2011 and completed full mapping of planet in 2013.
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Authored by BK Suthar.
This site is about various topics of astronomical and geographical things which present in universe and also surrounding us. It will give you information about various planets, incidents occurs in universe and also about nature.
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