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 ...

Scientists have always been curious about the atmosphere surrounding us, but in the past, they could not just hop on a spaceship to see what was up there. Instead, scientists hiked up high ...

The Earth formed over 4.6 billion years ago out of a mixture of dust and gas around the young sun ... By the time of the moon-forming impact, the Earth was already separated into these rock and metal ...

There's a lot more to Earth than meets the eye. Far from being just a roundish rock barreling through space, our planet is composed of several layers held together by intense forces of gravity.

Laid down over millions of years, these rock layers contain a permanent ... Some three billion years ago, the Earth's atmosphere was virtually devoid of oxygen. At about 2.4 billion years ago ...