Here's why:
* Extreme pressure: The immense pressure from the weight of the Earth's mantle and crust keeps the outer core in a liquid state, even though the temperature is incredibly high (around 4,500°C to 5,500°C).
* Convection currents: The liquid outer core is constantly moving, creating convection currents. This movement generates Earth's magnetic field.
* Seismic waves: Scientists have studied how seismic waves travel through the Earth and found that the outer core behaves as a liquid.
The solid inner core, on the other hand, is made of iron and nickel, but it's under such immense pressure that it's a solid even though its temperature is even hotter than the outer core.
