Mercury is the closest planet to our Sun and one of the most fascinating planets in our solar system overall! From its surface, the Sun would appear 3x larger than when viewed from Earth and the sunlight would be 7x brighter. Mercury doesn’t have any moons or rings, but that doesn’t mean it isn’t interesting — on the contrary, Mercury is an incredible planet. We’ve rounded up some of our favorite fun facts about Mercury to help you learn more about this amazing planet!
#1 Mercury Is the Smallest Planet.
Mercury is the smallest planet in our solar system. To put it in perspective, Mercury is only slightly larger than Earth’s Moon.
#2 Mercury Experiences Massive Temperature Swings.
Because Mercury is located so close to the Sun, its surface temperature can reach up to 840 degrees Fahrenheit (450 degrees Celsius)! However, Mercury doesn't have much of an atmosphere to trap this heat, so temperatures can plummet to -275 F (-170 C) at night. This means that Mercury experiences massive temperature swings of more than 1,100 degrees F (600 degrees C) and has a greater temperature range than any other planet in our solar system!
#3 Mercury’s Surface Has Wrinkles.
This is one of our favorite fun facts about Mercury — the surface of the planet is wrinkled! This is because Mercury’s inner core has shrunk as it has cooled over time, causing the planet’s surface layer to crack and wrinkle. Interestingly, Mercury is approximately 7 km smaller today than it was when its crust first solidified over 4 billion years ago!
#4 Mercury Is Not the Hottest Planet.
Although Mercury is the closest planet to the Sun, surprisingly, it is not the hottest planet. Instead, the hottest planet is nearby Venus, whose dense atmosphere causes its surface to retain more heat and therefore reach extremely high temperatures.
#5 Mercury Is the Second Densest Planet.
Mercury is the second densest planet in our solar system (Earth is the densest). It has a large metallic core with a radius of about 1,289 miles and there is evidence that it’s partially molten. Mercury’s outer shell is comparable to Earth’s mantle and crust but is only about 250 miles thick.
Want even more fun facts about space? Learn all about Jupiter or discover how fascinating Earth’s Moon is here!