This field of study differentiates the study of Earth from the study of other planets in the Solar System, Earth being its only planet teeming with life. Hydrology, oceanography and limnology are studies which focus on the movement, distribution, and quality of the water and involves all the components of the hydrologic cycle on the Earth and its atmosphere (or hydrosphere). "Sub-disciplines of hydrology include hydrometeorology, surface water hydrology, hydrogeology, watershed science, forest hydrology, and water chemistry."[7] Glaciology covers the icy parts of the Earth (or cryosphere).