Question

Scientists have discovered that the inner core of Earth is a solid while the outer core is a liquid. What is the cause of this observation?

Answer 1

inner core of earth contain lava. and than it is solid...... it's not a good for population survived ........outer surface is liquid because it's called Buffer zone it surrounded the area limited allow the human activities..............

Answer 2

The reason is that the relative melting points of the different layers such as nickel-iron core, silicate crust and mantle are different and also temperature and pressure increases as we go deeper.

The surface nickel-iron alloys and silicates are cool so they are solid whereas in the upper mantle, they are melt, leading to some viscosity in the outer core.