Our amazing planet Earth, the water planet. In both liquid and frozen form, water covers 75% of the Earth’s surface, which is why Earth is known as the water planet. Water is practically everywhere on Earth, from inside the planet’s rocky crust to inside the cells of the human body. This detailed, photo-like view of Earth is based largely on observations from MODIS, the Moderate Resolution Imaging Spectroradiometer, on NASA’s Terra satellite.