Water & Planets
Hydrogen is by far the most abundant element in the Universe, dominating in stars, interstellar gas and the gaseous and icy planets. Water is thus an important volatile that was re-distributed through the solar system during its formation, and the abundance of water on planetary bodies is a key indicator for understanding the dynamics of solar system formation. Within planetary interiors, water is also important because it can influence the dynamic evolution of planetary bodies (see Water and Mantle Dynamics). Water is present as ice on the surface of many planets, and may be present in liquid form on a few other planets besides Earth. This surface water plays an important role in the tectonic, sedimentological, geomorphological, and climatic evolutions of these planets. Water may also be important for “exoplanets” that are orbiting stars outside our solar system.