Mercury is the solar system ‘s innermost planet and its eighth in size and mass. The closeness to the Sun and its smallness make it the most mysterious planet in size and mass apparent to the unaided eye. Planet Mercury, the innermost planet in the solar system and the eighth. The closeness to the Sun and its smallness make it the most mysterious of planets that are apparent to the eye without support.
Here are 15 interesting facts about planet Mercury.
1. Mercury is the closest planet to the sun. As such, it circles the sun faster than all the other planets, which is why Romans named it after their swift-footed messenger god.
2. The temperature during the day can reach 840 degrees Fahrenheit (450 degrees Celsius), but at night, temperatures can get as low as minus 275 F (minus 170 C). That fluctuation equals a temperature swing of more than 1,100 F (600 C), the largest of any planet in the solar system.
3. Mercury has been known to humanity since ancient times and although its discovery date is unknown, the first mentions of the planet are believed to be around 3000 BC by the Sumerians.
4. Despite being so small, Mercury is the second-densest planet in the Solar System after Earth. This means it is very compact.
5. Mercury is one of the rocky planets. It has a solid surface that is covered with craters. It has no atmosphere, and it doesn’t have any moons. Mercury likes to keep things simple.
6. When you stare at the surface of Mercury, you can’t help but realize that it resembles that of our moon. The surface is covered with a lot of craters that were caused by collisions with comets and meteoroids.
7. A completely unexpected discovery made by Mariner 10 was that Mercury possessed a magnetic field. Planets theoretically generate magnetic fields only if they spin quickly and possess a molten core. But Planet Mercury takes 59 days to rotate and is so small — just roughly one-third Earth’s size — that its core should have cooled off long ago.
8. Scientists think that there is ice inside Mercury’s craters. The planet’s north and south poles are cold and shadowy, which could allow them to retain water ice. Meteorites and comets could have delivered ice to those areas, or water vapor from Mercury’s innards could have seeped out and frozen.
9. The planet has just 38% of the gravity on Earth. This means that Mercury isn’t able to hold the atmosphere it has and it instead gets blown away by solar winds. However, those same solar winds are also bringing in new gases, radioactive decay, and dust from micrometeorites — replenishing the atmosphere.