Mercury is the closest planet to the sun in our solar system. The distance is 58 million kilometers, about a third of the way between the earth and the sun.
Mercury is just over a third the size of Earth, making it the smallest planet in the solar system.
With its surface shaped by countless craters, Mercury resembles our moon.
Mercury is the fastest planet in the solar system with a speed of 112,000 miles per hour (180,000 kilometers per hour).
If one were on the surface of Mercury, one could observe a strange phenomenon. It may be that the sun rises to a certain point in the sky and then sets back again. Afterwards the sun can rise again on the same Mercury day. This is only possible because the planet rotates three times while circling the sun twice.
Mercury has already been visited twice by space probes: 1974 by Mariner 10 and 2011 by Messenger. The BepiColombo probe started in 2018 and is expected to reach its destination in 2021.
A year, one circumnavigation of the sun, takes only 88 days on Mercury.
Scientists assume that Mercury used to be Trabant of Venus until it evaded its gravity.
Mercury is named after the Roman messenger to the gods.
The temperatures on mercury’s surface can vary between -279 degrees Fahrenheit (-173 degrees Celsius) at night and 801 degrees Fahrenheit (427 degrees Celsius) during the day. This is the most fluctuating temperature in the solar system.
Due to its small size, Mercury has too little mass and gravity for building a stable atmosphere. Solar winds can therefore easily blow away attracted gases.
Since Mercury is already visible to the naked eye during twilight, it is not clear who first discovered the planet. However, the astronomer Timocharis of Alexandria 265 BC was the first to record the observation.
Besides Venus, Mercury is the only planet that does not have a moon.
There is water ice on Mercury.
Mercury has the largest core in relation to its diameter. About 85 percent of the planet belongs to the core.
Mercury was hit by a giant asteroid an estimated four billion years ago. It left a Texas-sized crater – the Caloris Basin. It is 950 miles (1,525 kilometers) wide.
Mercury has at tail of rock particles. Scientists are still unsure, how to explain that phenomenon.
The rays from the sun are around seven times stronger on Mercury than on Earth.
When Pluto has circled the sun once, 1028 years have passed on Mercury.