Earth is a water world. More than 70 percent of our planet's surface is covered in water, and its presence allowed for the emergence and sustenance of life. But from where did Earth's water originate? Why is our planet apparently so wet and why are other planets so dry? Water is not only prevalent on the outside of our planet, but there may be oceans of water in its interior, too. How much water exists inside Earth and how does it get down there and back out again? What is the deep Earth's role in regulating the water on the surface? Dr. Walter will investigate these questions as we probe our "Deep Blue Planet."

Dr. Michael Walter: Director, Geophysical Laboratory, Carnegie Institution for Science