Earth's inner core

Earth's inner core is like the middle of an onion. It is the very center of our planet and is the hottest, most dense part of the Earth. It's a big ball of mostly iron and some other stuff that's very hard and very hot - so hot that the iron is actually melted! Its temperature is around 5000 degrees Celsius (9000 degrees Fahrenheit), which is even hotter than the surface of the Sun! Even though it's so hot, the inner core still puts pressure on the Earth's outer layers, like an inner strength that helps keep our planet together.