Astronomy Essay Example | Topics and Well Written Essays - 1000 words

Astronomy - Essay ExampleIts family pangs began some 4.6 billion years ago as rock and ice particles swirling around the young solarise collided and merged, snowballing to produce ever larger artificial satelliteary building blocks. In violent pileups, they smashed together to bring in planets, including the infant Earth. In the turmoil, another body, as big as Mars, struck our planet with the energy of trillions of atomic bombs, enough to melt it all the way through. Most of the impactor was swallowed up in the bottomless magma ocean it created. only when the collision also flung a small worlds worth of vaporized rock into orbit. Debris quickly self-possessed itself into a ball, and since then Earth history has unfolded beneath the blank stare of the moon.After the moons fiery birth, the Earths show up cooled. Even so, our planet remained an alien world for the next 700 million years scientists call this time the Hadean, subsequently the Greek underworld. Rafts of solid roc k drifted in the magma like dark ice floes. Gases hissed from the cooling system rock-carbon dioxide, nitrogen, irrigate vapor, and others-enveloping the planet in a scalding melodic phrase devoid of oxygen. As the temperature dropped further, the steam condensed into rain that fell in primordial monsoons and filled the ocean basins.These first oceans may have been short-lived. Space rubble left over from the birth of the planets-chunks of rock tens to hundreds of miles across-bombarded Earth throughout the Hadean. The greatest impacts might have boiled the oceans away, forcing the process of cooling and condensation to begin again.By 3.8 billion years ago the impacts relented. Liquid water could persist. About that time, perhaps in the oceans, lifeless chemical reactions crossed a threshold, producing molecules complex enough to reproduce themselves and evolve toward great complexity. Life was on a road that led, as early as 3.5 billion years ago, to single-celled, bluish gr een cyanobacteria that flourished in the sunlit parts of the oceans. By the trillions, these microscopic organisms transformed the planet. They captured the energy of the sun to get a enormous food, releasing oxygen as a waste product. Little by little they turned the atmosphere into breathable air, opening the way to the diversity of life that followed.Those days are long gone, but the processes that turned our planet from a hell to a habitable world are still on view today, as the images on these pages show. Primordial heat left over from the planets formation still bursts out in volcanic eruptions, spilling lava that exudes gases like the young, cooling Earth.In the planets harshest environments today, cyanobacteria reign as they have for billions of years. And each time a plant gains a toehold on newly cooled lava, the victory of life over lifeless rock-won so long ago on the young Earth-is affirmed again.Subscribe to National Geographic magazine.The Earth began as a bleak surr ounding where hot and fiery rocks and poisonous fumes existed. This is what the article from National Geographic Magazine, highborn Earth in the Beginning written by Tom Appenzeller, illustrates. The article describes the early Earth