Spoken by Carl Sagan in his award-winning series, Cosmos, this quote solidifies our intimately biological relationship with water.
“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”
Although you won't find water as we know to be water in the stars, you will find hydrogen and oxygen existing separately. Hydrogen was created during the Big Bang and is essential to the existence of the universe. Alternately, oxygen emerged from ongoing nuclear reactions within living stars. Whenever hydrogen and oxygen meet in space, the miracle of water happens.
Earth and Water Met Each Other Billions of Years Ago--But How?
Star births erupt with the power of a million hydrogen bombs, sending unfathomably enormous amounts of dust and gas into space. When this starstuff collides with space gas, the ensuing shock waves compress and heat interstellar gases, producing H2O in the form of water vapor.
For dozens of years, astro-biologists accepted the paradigm that comets helped bring life-giving water to a young, volatile Earth. Thought of as "dirty, rocky snowballs", comets may also have brought organic compounds to Earth that promoted development of early cyanobacteria. However, the comet-water theory has been put aside for now using advanced technology capable of analyzing the composition of comets and asteroids.
Heavy Water Comes to Earth
As a scorchingly hot planet following its formation over 4.5 billion years ago, Earth could not have possibly retained water during this period. Instead, scientists now think that cosmic debris striking the Earth in a later period they've termed the Late Heavy Bombardment probably gave Earth its very first drink of water. In fact, astro-biologists think it was asteroids and not so much comets that pummeled the Earth 800 million years after it coalesced and developed into a planet.
Comprised of one oxygen molecule and two hydrogen atoms, normal water molecules are found in all terrestrial water sources. Bumping alongside normal water molecules are also heavy water molecules, or H20 molecules that have their hydrogen atoms replaced with deuterium.
A chemical isotope similar to hydrogen but with an extra neutron crowding its nucleus, deuterium found in heavy water molecules indicates that asteroids probably brought water to the Earth and not Kuiper Belt comets.
No Water, No Life?
Author of Life's Matrix: A Biography of Water Philip Ball writes that
"water is essential for the kind of delicate chemistry that makes life possible ... water "is a universal solvent...mediator of life’s chemical reactions with astructure unlike that of any other liquid."
Although some astrobiologists believe it is possible that life forms not based on water, carbon and other terrestrial chemicals may exist on planets or moons, no such life has yet to be discovered. As of today, water remains the direct link to life, a precious, priceless commodity we should be doing more to preserve, protect and provide for future generations of humans and animals coexisting on Earth.
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