Water is a transparent fluid which forms the world’s streams, lakes, oceans and rain, and is the major constituent of the fluids of living things. As a chemical compound, a water molecule contains one oxygen and two hydrogen atoms that are connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice; and gaseous state, steam (water vapor).
Water covers 71% of the Earth’s surface. It is vital for all known forms of life. On Earth, 96.5% of the planet’s water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Only 2.5% of the Earth’s water is freshwater, and 98.8% of that water is in ice and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth’s freshwater (0.003%) is contained within biological bodies and manufactured products.
Up to half of the water on Earth and throughout our solar system likely originated as ices that formed in interstellar space.
A new study in the journal Science, published September 26, 2014, suggests that much of the water on Earth and throughout our solar system likely originated as ices that formed in interstellar space. If so, it means that water may be more widespread in planetary systems than previously thought.
The researchers’ work addresses a debate about just how far back in galactic history our planet and our solar system’s water formed. Were the molecules in comet ices and terrestrial oceans born with the system itself—in the planet-forming disk of dust and gas that circled the young sun 4.6 billion years ago? Or did the water originate even earlier, in the cold, ancient molecular cloud that spawned the sun and that planet-forming disk?
The new research suggests that between 30 and 50 percent came from a molecular cloud. That would make it roughly a million years older than the solar system.
Artist’s concept showing the time sequence of water ice, starting in the sun’s parent molecular cloud, traveling through the stages of star formation, and eventually being incorporated into the planetary system itself.
All life on Earth depends on water. Understanding when Earth’s water came to be – and where it came from – can help scientists estimate how common water might be throughout the galaxy.Our findings show that a significant fraction of our solar system’s water, the most-fundamental ingredient to fostering life, is older than the sun, which indicates that abundant, organic-rich interstellar ices should probably be found in all young planetary systems.
How Water Works
In its purest form, it’s odorless, nearly colorless and tasteless. It’s in your body, the food you eat and the beverages you drink. You use it to clean yourself, your clothes, your dishes, your car and everything else around you. You can travel on it or jump in it to cool off on hot summer days. Many of the products that you use every day contain it or were manufactured using it. All forms of life need it, and if they don’t get enough of it, they die. Political disputes have centered around it. In some places, it’s treasured and incredibly difficult to get. In others, it’s incredibly easy to get and then squandered. What substance is more necessary to our existence than any other. water
At its most basic, water is a molecule with one oxygen atom and two hydrogen atoms, bonded together by shared electrons. It is a V-shaped polar molecule, which means that it’s charged positively near the hydrogen atoms and negatively near the oxygen atom. Water molecules are naturally attracted and stick to each other because of this polarity, forming a hydrogen bond. This hydrogen bond is the reason behind many of water’s special properties, such as the fact that it’s denser in its liquid state than in its solid state (ice floats on water).