Mercury (planet) explained to kids

Mercury is the smallest and innermost planet in our solar system. It's about a third the size of Earth and only slightly larger than Earth's moon. Mercury is the closest planet to the Sun, so it orbits the Sun faster than any other planet. A day on Mercury is only 58 Earth days long, but a year on Mercury is 88 Earth days long. Mercury is very hot! The side of Mercury that faces the Sun can reach temperatures of 800 degrees Fahrenheit (430 degrees Celsius). The side of Mercury that faces away from the Sun is much cooler, only -290 degrees Fahrenheit (-180 degrees Celsius). Mercury doesn't have any moons. It also doesn't have an atmosphere, which means that there is no wind or weather on Mercury. Mercury is very rocky and has a lot of craters. Scientists believe that Mercury was once hit by a huge object, which caused it to have a very thin crust. Because Mercury is so close to the Sun, it's hard for us to study it. NASA's Mariner 10 spacecraft was the first to visit Mercury. Mariner 10 took pictures of about 45% of Mercury's surface. In 2004, NASA's Messenger spacecraft became the first to orbit Mercury. Messenger took pictures of the entire surface of Mercury! In 2015, Messenger crashed into Mercury. Mercury is a very interesting planet, and we are still learning a lot about it!