World time line1/17/2024 Because water shielded harmful radiation, that’s where life existed. Before the presence of an ozone layer, life was restricted to shallow water. But the abundance of CO 2 held eukaryotes from diversifying.Īs oxygen filled the atmosphere, Earth’s ozone layer thickened. For example, multi-cellular organisms became apparent in this eon. Eventually, aerobic respiration organisms emerged because of the enriched atmosphere. Before the oxygenation, life was anaerobic. It was “Snowball Earth” as the Earth went into an ice age for the next 300,000,000 years.Īnother important consequence of an oxygen-filled atmosphere was the emergence of aerobic eukaryotes. All of a sudden, the greenhouse effect wasn’t as strong. So when oxygen combined with methane, it produced carbon dioxide. It’s one of the most efficient greenhouse gases there are. One thing that methane did very well was trap heat in the atmosphere. The oxygen byproduct from cyanobacteria created an oxygen crisis on Earth.Īt this time, methane was more abundant in the atmosphere. Imagine a dominant species polluting the planet until extinction. Because oxygen was toxic for cyanobacteria, they poisoned all anaerobic life on Earth including themselves. That’s why this event is the Great Oxygenation Event.Įarth now had an oxygenated atmosphere for new life to flourish on Earth. Oxygen had nowhere to go but into the atmosphere. The banded iron formation continued until there was no more iron in the oceans to rust. When oxygen mixed with iron in the oceans, rusted iron collected on the seafloor. As a waste product, cyanobacteria released oxygen into the oceans. In shallow water, they metabolized their own food. When oxygen was absent in the atmosphere, cyanobacteria could convert sunlight to energy. Though opinions vary, “Vaalbara” became Earth’s first supercontinent.Īs the Earth cooled down, a new form of life began to prosper. And the Earth cooled down enough to create continents. Instead of a molten state, the Earth started to cool down. And because the Earth is tilted on its axis, Earth now had seasons.Įventually, the climate on Earth became more stable in the Archean Eon. But most importantly, the collision of the moon tilted Earth on its axis. Having the moon in orbit also stabilized the Earth from wobbling. Because the moon’s orbit drags Earth, it slowed Earth’s rotation significantly from 6-hour days to 24 hours. The collision of the moon into Earth significantly impacted climate, oceans, and life on Earth. Ever since this grande event in the Hadean Eon, it has remained in orbit ever since.Įarth Cooling and Primitive Life (4.0 – 2.5 billion years ago ) After delivering a glancing blow to Earth, gravity pulls this object into orbit. The giant impact hypothesis describes it as an object the size of Mars heading towards Earth at tremendous speed. One of the most important events for Earth was the formation of our moon. In addition, there’s reason to believe that these collisions could have sparked the chemical building blocks for life – DNA. ![]() ![]() Some scientists believe that water originated from the bombardment of comets at this time. We know it wasn’t only Earth because we can see these impacts on other places in our solar system. Earth was hit by asteroids, comets, and foreign objects left, right, and center. In the late Hadean Eon, the Earth was still in its late heavy bombardment stage. Without it, Earth would be blasted by harmful rays from the sun. This geodynamo is Earth’s magnetic field. Because the solid inner core heats the outer liquid layer, it produces convection currents. Lighter material remained on top to form a crust. In this early stage of Earth’s creation, the heaviest material like iron sank to the core. Based on the core accretion model, gravity was the driver coalescing Earth from a cloud of dust. Farther away, heavier elements formed planets. At the center, the sun swept in smaller elements like hydrogen and helium. This includes the sun, planets, and our solar system. ![]() The Big Bang created all matter in the universe. The Sculpting of Earth (4.6 – 4.0 billion years ago )
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