A crew of four passengers — led by a cryptocurrency billionaire — is set to launch aboard a SpaceX capsule that will carry them over the Earth’s poles ... the SolarMaX project is to capture ...

The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun. The deepest layer is a solid iron ball ...

Over time, Earth's interior—which is made mostly of silicate rocks and metals—differentiated into four layers. At the planet's heart lies the inner core, a solid sphere of iron and nickel that ...