picture credit NASA
Discovered by: The Ancients
Date of Discovery: Unknown
Namesake: Messenger of the Roman Gods
Distance from Sun (average): 57, 909,175 km
Equatorial Radius: 2,439.7 km (.3825 of Earth)
Equatorial Circumference: 15,329.1 km
Volume: 60,827,200,000 km3 (.054 of Earth)
Mass: 3.3022 x 1023 kg (.055 of Earth)
Density: 5.427 g/cm3 (.984 of Earth)
Rotational Period: 58.646 Earth days
Time to orbit Sun: 88 Earth days
Temperature Range: -300 to 800° Fahrenheit (-184 – 427 Celsius)
Equatorial Surface Gravity: 3.7 m/s2 (100 Earth pounds would be 38 pounds on Mercury)
Moons: None known.
The closest planet to the sun and also the smallest, Mercury is a violent mix of temperatures. While the side facing the sun rages at over 800 degrees Fahrenheit, the opposite side plummets to a frigid -300 due to its lack of a real atmosphere.
Because of the low surface gravity, if you weighed 100 pounds here on Earth, you would only weigh about 38 pounds on Mercury.
The Messenger mission is slated to orbit Mercury in 2011. While 98% of the planet has been photographed, Messenger hopes to capture the remaining 2% at the poles.
Mercury rotates very slowly, only making one complete rotation in just shy of 59 Earth days – every Mercurian day is almost two months on Earth! Yet it orbits the sun every 88 Earth days. More confusingly, this means that the “solar day” – the period of time which is exposed to sunlight – is 176 days long. At 800 degrees, expect some sunburn.
The Planets Part 1: Mercury
The Planets Part 2: Venus
The Planets Part 3: Earth
The Planets Part 4: Mars
The Planets Part 5: Jupiter
The Planets Part 6: Saturn
The Planets Part 7: Uranus
The Planets Part 8: Neptune
The Planets Part 9: The Dwarf Planets