1. Size: Mercury is the smallest planet in our solar system; it is only slightly larger than Earth’s moon
2. The sun: Although Mercury is the closest planet to the sun (at a distance of around 58 million km), Venus is the hottest planet in our solar system
3. Day: 1 day on Mercury (i.e. the time it takes Mercury to rotate around its axis once) is equivalent to 59 days here on Earth
4. Year: 1 year on Mercury (i.e. the time it takes Mercury to rotate once around the sun) is equivalent to 88 days here on Earth
5. Speed: Mercury’s orbital speed is almost 50 km per second (Earth’s is about 30 km/s), making it the fastest planet in our solar system
6. The appearance of the sun: If you stand on the surface of Mercury when the planet is closest to the sun, the sun will appear more than 3 times larger than on Earth
7. Surface: Mercury’s surface consists of rocky deserts with craters – much like the surface of our moon
8. Temperatures: Temperatures on Mercury can reach 430 degrees Celsius during the day and drop to -180 degrees Celsius at night, making it highly unlikely that any form of life (as we know it) can survive here
9. Characteristics: Mercury has no moons or rings. Mercury also has no atmosphere, but instead has a thin “exosphere” consisting primarily of oxygen, sodium, hydrogen, helium and potassium
10. Name: The name ‘Mercury’ comes from Roman mythology, where Mercury was the god of communication, speed and commerce

Fact: Temperatures on Mercury can reach up to 430 degrees and drop as low as -180 degrees

More facts about Mercury

• Magnetic field: Mercury’s magnetic field has only 1% of Earth’s magnetic field strength (on the surface)
• Axis tilt: Mercury has the smallest axial tilt of all the planets in the solar system (0.01° to the ecliptic)
• Visibility: Because Mercury is so close to the Sun, it is difficult to see the planet from Earth. In practice, this is only possible at dawn or dusk. However, there is a period called the “Mercury transit”, which occurs 13 times every century, when Mercury can be seen passing in front of the Sun. The Mercury transit lasts several days and falls sometime between May 03 and November 14. Read more about Mercury Passage here
• Circulation: Among the planets in the solar system, Mercury has the most eccentric orbit. In its orbit, Mercury is at its closest point only 47 million km from the sun and at its farthest point 70 million km from the sun (almost 33% difference) – in comparison, Earth is 146 and 152 million km from the sun at its most extreme points (about 4% difference)
• Spacecraft: Only 2 spacecraft have visited Mercury:
  • Mariner 10, which took images of approximately 45% of Mercury’s surface
  • MESSENGER, which visited Mercury three times in 2008-2009 and orbited Mercury in 2011 (and still does). Almost the entire surface is now imaged