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Solar System Exploration
Mercury: Facts & Figures
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Discovered By
Known by the Ancients
Date of Discovery
Orbit Size Around Sun (semi-major axis)
Metric: 57,909,227 km
English: 35,983,125 miles
Scientific Notation: 5.7909227 x 107 km (0.38709927 A.U.)
By Comparison: Earth is 1 A.U. (Astronomical Unit) from the sun.
Perihelion (closest)
Metric: 46,001,009 km
English: 28,583,702 miles
Scientific Notation: 4.600 x 107 km (3.075 x 10-1 A.U.)
By Comparison: 0.313 x Earth
Aphelion (farthest)
Metric: 69,817,445 km
English: 43,382,549 miles
Scientific Notation: 6.982 x 107 km (0.4667 A.U.)
By Comparison: 0.459 x Earth
Sidereal Orbit Period (Length of Year)
0.2408467 Earth years
87.97 Earth days
By Comparison: 0.241
Orbit Circumference
Metric: 359,976,856 km
English: 223,679,248 miles
Scientific Notation: 3.600 x 108 km
By Comparison: 0.383 x Earth
Average Orbit Velocity
Metric: 170,503 km/h
English: 105,946 mph
Scientific Notation: 4.7362 x 104 m/s
By Comparison: 1.590 x Earth
Orbit Eccentricity
By Comparison: 12.305 x Earth
Orbit Inclination
7.0 degrees
Equatorial Inclination to Orbit
0 degrees
By Comparison: Earth's equatorial inclination to orbit is 23.45 degrees.
Mean Radius
Metric: 2,439.7 km
English: 1,516.0 miles
Scientific Notation: 2.4397 x 103 km
By Comparison: 0.3829 x Earth
Equatorial Circumference
Metric: 15,329.1 km
English: 9,525.1 miles
Scientific Notation: 1.53291 x 104 km
Metric: 60,827,208,742 km3
English: 14,593,223,446 mi3
Scientific Notation: 6.08272 x 1010 km3
By Comparison: 0.056 x Earth's
Metric: 330,104,000,000,000,000,000,000 kg
Scientific Notation: 3.3010 x 1023 kg
By Comparison: 0.055 x Earth's
Metric: 5.427 g/cm3
By Comparison: 0.984 x Earth
Surface Area
Metric: 74,797,000 km2
English: 28,879,000 square miles
Scientific Notation: 7.4797 x 107 km2
By Comparison: 0.147 x Earth
Surface Gravity
Metric: 3.7 m/s2
English: 12.1 ft/s2
By Comparison: If you weigh 100 pounds on Earth, you would weigh 38 pounds on Mercury.
Escape Velocity
Metric: 15,300 km/h
English: 9,507 mph
Scientific Notation: 4.25 x 103 m/s
By Comparison: Escape Velocity of Earth is 25,030 mph
Sidereal Rotation Period (Length of Day)
58.646 Earth days
1407.5 hours
By Comparison: 58.81 x Earth
Minimum/Maximum Surface Temperature
Metric: -173/427 °C
English: -279/801 °F
Scientific Notation: 100/700 K
By Comparison: Earth's temperature range is ~ 185/331 K.
Atmospheric Constituents
By Comparison: Earth's atmosphere consists mostly of N2, O2

Additional Information:

Namesake: Messenger of the Roman gods

Successive Sunrises: 175.97 days

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Last Updated: 21 Jan 2015