How Planets Are Formed
The suns creation
4.6 billion years ago, a ginormous cloud of gas and dust which is called a solar nebula was swirling in the milky way. Nearby there were hot stars, burning up and destroying themselves in a massive explosion called a supernova. The explosion destabilizes the clouds and they collapse. In 100,000 years, gravity and angular momentum flattens the clouds into a single spinning disk. In the center of this disk, molecules are crashing together tightly. Deep inside the disk, clumps of dust that are not much larger than a grain of wheat are flash heated into molten rock. Where this heat came from still remains a mystery today. These small pieces of molten rocks are what became the building bocks of our solar system. Because of gravity and turbulence, the pieces clump together and grow into the first asteroids. They then grow into mountains, which become planets. These astroids are piles of rubble, rock, metal and ice. A very large asteroid was soon to become the parent body of Bennu, a protoplanet which could be any guessable size. Closer to the protostar, a planet begins to form. The protostar undergoes fusion and it ignites, morphing into our star.
How the earth was created
A rocky mass created by clumps of molten rock emerged from a cloud of dust and it began to rotate around the sun. No organism could yet survive there because of the radiation from a nearby supernova. The heat from the supernova made the temperatures on this ball of rock extremely hot. So extremely hot that the surface of the future planet was molten rock. And oxygen was also not yet existent. There were also many asteroids and meteorites randomly slamming into the surface of the rocky mass. Over time, the ball of rocks (known as earth) got so hot that it began to melt. Heavier materials sank to the core and lighter elements rose to the top, and some even evaporated. This created the earths layers. The core, mantle, and crust. It also created the atmosphere and earths magnetic field. Without the atmosphere and magnetic field, the earth would get constantly blasted by the deadly rays from the sun. At this point in earths life, its still in the bombardment stage. There is still no life and temperatures are still extremely hot. Too hot for any living thing to exist. There is also constant volcanic activity. Volcanoes are exploding everywhere and lava is coating the crust. It truly appeared to be hell on earth. The atmosphere is nebular. At this point, it was possible that there were small bodies of water at liquid state. The building blocks from DNA are also believed to be from the space collisions that first formed the earth. Over a long period of time the earth started to cool down. The climate became more stable for life to thrive, rather than a molten rock. The earth cooled down enough to create continents. It started out as one supercontinent, but soon broke down into many pieces. Around 3.2 billion years ago, photo synthetic organisms began to appear which enriched the atmosphere with oxygen. Simple cell organisms began to exist and absorbed the suns energy and they filled the ocean with oxygen. This is called photosynthesis. Around this time, methane was abundant in the atmosphere, which helped trap heat in the atmosphere. This lead to the greenhouse affect not being as strong, which lead to the whole planet freezing for the next three hundred million years. This was known as an ice age.
Life on earth
As oxygen filled the atmosphere, the ozone thickened and strengthened. At first, any life that existed lived under the surface of the ocean because the ozone layer was not yet strong enough. The suns deadly rays would strike right through it and any organism to come out of the ocean would die. But, the layer eventually thickened. Since the ozone layer thickened, the organisms were now protected from the rays. And soon after, the ozone layer thickened even more allowing life to diversify on land rather than strictly in the shallow waters of the ocean. Fish started to thrive in the ocean, and fungi and plants began to venture outside of the water which caused them to have to adapt to the new conditions on dry earth. Some fish stayed close to land and adapted to life there and developed lungs. Amphibians were the first vertebrae to convert to life on land. Living on land benefited these creatures because food was plentiful and there were no predators. That was the beginning of the age of amphibians. 250 million years ago was the permian extinction which wiped out 95% of all living species. Earths climate became drier and warmer, the rainforests collapsed which lead to the age of reptiles. This is when the super continent, called Pangea, existed. All of the dinosaurs lived on this one continent. Plate tech-tonics began to tear apart the continent. Dinosaurs started to drift apart with the continents. With yet another astroid impact, the age of mammals began. The asteroid wiped out most of the dinosaurs. This is when the mammals began to thrive. Mammals evolved from mammal like reptiles. Birds evolved from small theropod dinosaurs. The change to mammals accelerated after the extinction of the dinosaurs. Since dinosaurs were the largest and mammals were the smallest, when the dinosaurs became extinct the mammals started to grow in size. Primates took to the trees to stay safe and obtain food. These primates became apes. Only a few million years ago is when it was believed that human life started to evolve. When grass began to spread in places like the African savanna and the number of trees started to decline, apes stopped climbing in trees and were forced to start walking on two legs. This was just the beginning of the human race.
