Less Than Five Episode 03 - How did Planet Earth Form?\r\n\r\nNearly 4.6 billion years ago, deep in the Milky Way galaxy, a vast cloud of gas and dust swirls around. Called a solar nebula, this cloud will ultimately host a newborn star, our Sun. But, how did our home first come to life? Astronimate breaks this mystery down in How did Planet Earth Form?\r\n\r\nHow did planet Earth form: Simple definition\r\n\r\nIn short, Earth spawned from dust and dirt swirling around the Sun. In fact, all inner planets (Mercury, Venus, Mars) formed this way! However, several complex processes first took place in order to magically create the rocky inner solar system we know today. Technically, this method for Earth's formation discussed here is one of dozens of current theories, called the accretion theory. Though, this theory is currently the most widely accepted.\r\n\r\nHow did planet Earth form: The cloud collapses\r\n\r\nInitially, the vast cloud swirling in space began buckling under its own powerful gravity. Because of this, the cloud collapses, flattens and becomes a rapidly spinning disc. In physics, this process is called the conservation of angular momentum. Actually, we also see this when a figure skater pulls their arms close to their body to spin faster.\r\n\r\nHow did planet Earth form: The Sun is born\r\n\r\nAt this time, the strong gravity of the now flattened cloud sucks the gases into the center. Gradually, this gas builds up, coalesces and forms a massive ball of charged particles. Ultimately, the energy generated by this gas ball is tremendous. In fact, heat and pressure become so strong that the process of nuclear fusion initiates. Finally, this energetic nuclear factory becomes a full-on star; our Sun.\r\n\r\nHow did planet Earth form: The planets come to life\r\n\r\nCurrently, the new Sun blasts powerful solar winds across the entire disc. And, lighter materials such as hydrogen or helium are blown far out. Ultimately, these light elements will coalesce in the outer regions, forming the outer gas giant planets.\r\n\r\nHowever, heavier material, like dirt and dust are able to resist the solar winds. This heavy material remains close to the Sun, slowly clumping together. Eventually, these dirt clumps form the prototypes of the rocky, inner planets.\r\n\r\nHow did planet Earth form: The Earth's core and crust form\r\n\r\nEarth's rocky core forms first. Naturally, the heaviest materials, like iron and nickel gravitate to the new planet's center. Ultimately, these heavy elements will shape the Earth's core as we know it today. First, the solid central core, made primarily of iron. Next, the liquid outer-core, made of nickel-iron alloy.\r\n\r\nThen, lighter materials gravitate outward, eventually forming the Earth's crust. Materials such as silicon, aluminum and magnesium take shape to construct the mantel and crust we know today.\r\n\r\nHow did planet Earth form: Earth gets its atmosphere\r\n\r\nAt this time, the new Earth possesses a powerful gravity. As a result, the new planet slowly traps stray gases floating around the newly-laid solar system. In fact, Earth is thought to have had multiple atmospheres in its young life.\r\n\r\nFirst, the abundance of heated hydrogen and helium moved rapidly around the new solar system. However, the gases moved to quickly, they escaped Earth's gravity.\r\n\r\nLater, young Earth's volcanos spewed H20, or water, in the form of steam.Plus, carbon dioxide and ammonia. Clearly, this was also not the friendly atmosphere we now know.\r\n\r\nFinally, as plants and animals later thrive in a balanced new environment, our modern atmosphere is generated. Plants take in CO2, giving off oxygen. Animals take in oxygen, ultimately giving off CO2. Not to mention, fire and other human burning process also gradually give off CO2.\r\n\r\nDANGER: Theia, the wandering kamikaze planet!\r\n\r\nNearly 1-billion years after Earth formed, a near-deadly impact occurs. Theia, a wandering planet the size of Mars strikes Earth, causing near-catastrophic damage!\r\n\r\nHow did planet Earth form: Theia gives us our Moon\r\n\r\nUpon the devastating blow issued by Theia's impact, millions of pieces of the new Earth blast into space. Due to Earth's strong gravity many pieces are trapped. Ultimately, these salvaged Earth chunks clump together, forming our only natural satellite, the Moon!\r\n\r\nHow did planet Earth form: Earth get water\r\n\r\nToday, comets are rather rare in the inner solar system. In fact, comets only occur once every several decades, or more!\r\n\r\nHowever, in our solar system's early eras, comets were very abundant throughout the entire system. Not to mention, these early comets often collided with Earth. Actually, these impacts are thought to have caused our life-saving watery surface. As the icy comets collided with a hot young Earth, their melted contents slowly turned Earth's fiery surface into our oceanic home of today.