How is the Earth like an onion? In this video from PBS Digital Studios, viewers first learn the different layers of Earth and their properties. In addition, they hear how these layers came about, starting with the Big Bang theory and the...

What are the other two spheres on Earth? The hydrosphere and atmosphere, of course! This is the focus of a video that explains what makes up the hydrosphere and atmosphere.

Earth's thick atmosphere plays a vital role in the ability of the planet to sustain life. Learn about the layers of the atmosphere and their properties, how the gases surrounding the earth help protect the planet, and a little about...