Poor Mercury. I’ve been thinking about poor Mercury since we got this floor puzzle of the planets that pictures them in order with their names labeled and a planet fact for each one. Can you guess what Mercury’s was?
Mercury is the closest planet to the Sun.
Yes, it’s true, but obvious in the puzzle’s art. Couldn’t they have come up with a better fact than that? (PSA: This puzzle was low quality–the pieces are thin and were a little warped, so it doesn’t hold together at all well.)
An internet search, too, reveals that Mercury primarily tends to be defined by its nearness to the Sun.
So I figured it’s time for some Mercury appreciation. Here are some other stand-out facts about Mercury:
- Mercury is the smallest planet in the Solar System (we’re not counting dwarf planets). Mercury is only slightly larger than Earth’s Moon.
- A single day on Mercury lasts 59 Earth days. A year on Mercury is only 88 Earth days.
- Mercury travels through space at nearly 31 miles (50 kilometers) per second, which is faster than any other planet.
- Mercury has the biggest temperature change from day to night, with daytime temperatures of 800 degrees Fahrenheit (430 Celsius) and nighttime temperatures of -290 degrees Fahrenheit (-180 Celsius).
- Mercury’s eccentric orbit takes the planet as close as 29 million miles (47 million kilometers) and as far as 43 million miles (70 million kilometers) from the Sun. If you could stand on Mercury’s daytime surface when it’s at its closest point to the Sun, the Sun would appear three times as large as it does when viewed from Earth.
- Mercury has neither a moon nor rings, but it does have a wispy, comet-like tail streaming off the planet away from the sun. This is made of escaping gases, atoms blasted off the planet’s surface by the solar wind.
- The first spacecraft to visit Mercury was Mariner 10, which imaged a little less than half of the surface. It caught an immense impact basin on Mercury, called the Caloris Basin, and on the opposite side of the planet from the Caloris Basin is a spot that has been referred to as “weird terrain” ever since, because it looks weird and different from other areas of Mercury. (A more scientific name is “The Hilly and Lineated Terrain.”) It has some hills that look a little like rectangular blocks.
Of these facts, I especially like the tail and weird terrain. For more Mercury goodness, you can check out NASA’s Solar System Exploration pages about Mercury, or do your own web search to see how many articles start out with “Mercury is the closest planet to the Sun.”
By the way, did you know that in the 19th century, some folks thought that there might be another planet between Mercury and the Sun? They called it Vulcan, the name later given to Spock’s home planet in the Star Trek universe. If Vulcan existed, then Mercury would not be identified as the closest planet to the Sun.” More about the hypothetical planet Vulcan can be found here.