33 Important Facts About Mercury [The Swift Planet]

Last updated on February 14th, 2020

18. Mercury is also called a morning or an evening star because it is brightly visible in the sky just before the sunrise and just after the sunset.

19. Mercury is one of the five planets in the solar system that are visible to the naked eye. The other four are – Venus, Mars, Jupiter and Saturn.

20. NASA’s spacecraft “MESSENGER” crash landed on Mercury in April 2015. The spacecraft provided a lot of detail about the planet through images that will be used by the scientists to known more about this terrestrial planet in the future.

statistics on the MESSENGER mission.
Statistics on the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission. Image credit: NASA

Facts about its research and exploration

21. Galileo Galilei observed Mercury for the first time in 1631.

22. Mercury has seen only two guests from Earth – “Mariner 10 and the Messenger probe.” The reason behind limited space crafts being sent to Mercury: its close proximity to the Sun which makes it difficult for the space crafts to survive in the intense heat.

23. Mariner 10 is the first spacecraft to reach one planet by using the gravity of the other (in this case, Venus) to alter its speed and trajectory. The spacecraft lifted off from Cape Canaveral, Florida, on 3 November 1973.

24. As suggested by the images that were collected by space crafts, the surface of Mercury is formed mainly by impacts and volcanic activities.

25. There are no seasons on Mercury. All it has is a weak atmosphere that has 38% the gravity as experienced on Earth.

26. Mercury (it takes roughly 88 Earth days to complete a single orbit around the Sun) does not complete one revolution around the sun in a year and is the only planet to do so. It actually completes three revolutions on its own axis (the planet has a slow rotational period of 58.646 days) during the time it completes two revolutions around the sun.

27. The least circular and the most eccentric orbit in the solar system belongs to Mercury. And remember, a planet’s orbit has a lot to do with other conditions on it including temperature and atmosphere.

28. The presence of some ancient lava fields on the planet’s surface suggests that there was some volcanic activity on Mercury in the past.

29. As per the observations made and data collected by the scientists, mercury has shrunken in size. It has lost 1.5 km of its diameter since its formation. This is mainly due to the solidification of its core as it cools down.

30. Mercury is also a tectonically active planet like Earth. As the core cools down, it causes changes in its surface and produces scarfs and cliffs.

31. “BepiColombo” — named after a famous Italian mathematician and scientist – Giuseppe (Bepi) Colombo (1920-1984) — is ESA’s mission to mercury that will be launched in 2018. The multi-spacecraft mission will take at least 7 years to reach its orbit around Mercury. This will be a joint mission between Japan Aerospace Exploration Agency and ESA. During its journey to Mercury, the mission will see 9 flybys of Earth, Venus, and Mercury.

32. Scientists have imaged Mercury almost entirely with the help of the space crafts that were sent on various exploration missions.

33. Mercury is not tidally locked to the Sun. This fact is clear from the fact that it makes three revolutions on its own axis during the time it makes two revolutions around the Sun. Moon, however, is tidally locked to Earth as it takes the same amount of time to rotate on its own axis as it takes to revolve around the Earth.

Mercury – Quick facts

Date of discoveryUnknown
Discovered byKnown by the Ancients
Orbit Size Around Sun57,909,227 km
Mean Orbit Velocity170,503 km/h
Equatorial Inclination0 degrees
Equatorial Radius2,439.7 km
Volume60,827,208,742 cubic km
Mass330,104,000,000,000,000,000,000 kg
Density5.427 grams per cubic centimeter
Surface Area74,797,000 square km
Surface Gravity3.7 meter per second square
Escape Velocity15,300 km/h
Surface Temperatureminus 173 to 427 °C
Atmospheric ConstituentsNitrogen, Oxygen and others