How big is the outer core?

The Outer Core is the second to last layer of the Earth. It is a magma like liquid layer that surrounds the Inner Core and creates Earth's magnetic field. In this section you will learn about how Earth's magnetic field is created, how hot it is, how thick the Outer Core is and a few interesting facts about the Outer Core. read more

The inner core is thought to be 2,440 km across, and when you include the liquid outer core of the Earth, the entire core measures 6,800 km across; about twice as big as the Moon. It’s believed that the core of the Earth formed early on in our planet’s history, when the entire planet was made of molten rock and metal. read more

The Earth's inner core is thought to be slowly growing as the liquid outer core at the boundary with the inner core cools and solidifies due to the gradual cooling of the Earth's interior (about 100 degrees Celsius per billion years). read more