THE EARTH'S FORMATION |BeSci TV
Channel: BeSci TV
Date: 2020-10-15

BeSci TV
THE EARTH'S FORMATION

Earth’s Formation – Tutorial Script
     Humans are made up 70% of water: H-2-O. Where does the hydrogen come from? The oxygen? Carbon? How about the gold, platinum, and titanium? In this video, we’ll review the age and formation of Planet Earth and the important events that cooked up the ingredients that make us and our planet what we are today. This scaled timeline highlights key events that have happened since the formation of our universe 13.7 billion years ago. Note the 4.6 billion-year-age of Earth’s formation means it happened a LONG time after the universe formed. The dot here at the bottom represents today. What has been happening in our universe over all this time? And where are the dates and details of our timeline coming from? We learn about the history of our universe through centuries of study by scientists of objects in our solar system and beyond. We gather data from sky observatories, shuttle missions, satellites, ocean research vessels, and fleets of field and lab scientists like geologists, oceanographers, and geographers exploring the earth inside and out. Every day new data are collected. And every day our understanding evolves. We test our hypotheses. We turn them into theories that underpin our understanding of natural phenomena like gravity and light. Scientists will rarely say they “know” something because scientific knowledge is not static. It grows richer and more refined as we gather new data. So here’s a good basic mantra to take us through our explorations of Earth: act like a scientist and question everything! 13.7 billion years ago, the Universe exploded forth in an instant in time, from an infinitesimally small point, and has been expanding outwards ever since. How do we know? Astronomers observe that galaxies surrounding our galaxy are moving away from us. Space itself is stretching, pulling all galaxies, including ours, with it. It’s like being in an expanding balloon. All objects move away from the center AND from each other. If we imagine running a movie of the expanding Universe backwards, we move back in time to when galaxies were much closer together. If we continue running time backwards, we eventually come to a time when everything seemed to have existed in the same place at the same time.. The time it took to rewind was 13.7 billion years. At that point and time, astronomers hypothesize that there was a big explosion of energy, which over time expanded, cooled, and eventually led to the formation of all the known objects in the Universe. We call that initial energy explosion the Big Bang. In the first few seconds and minutes after the initial explosion, some of the energy transformed into subatomic particles, like protons and electrons. The first atoms formed, and by 3 minutes after the Big Bang, the universe contained by mass 75% hydrogen atoms (identified by having just 1 proton in the nucleus) and 25% helium atoms (identified as having just 2 protons in the nucleus). Now let’s jump ahead to 1 billion years after the Big Bang, when we see our oldest evidence of stars forming. How? Perturbations in clouds of hydrogen and helium gas cause collisions and accretion (where gas atoms stick to each other, much like dust particles sticking to each other under furniture). These small collections grow larger as they continue to collide and accrete with each other. As they become more massive they produce a large gravitational field that compacts them into hot dense balls and attracts and pulls in even more gas. The contraction also causes spin, and gas clouds become rotating disks. The center of the disk usually contains the largest concentration of gas, and eventually those balls of gas can become so dense and hot that nuclear fusion can occur in their cores. Nuclear fusion is a process by which atomic nuclei fuse together to create new atoms. For example, when one hydrogen (1 proton in the nucleus) fuses with another hydrogen (1 proton in the nucleus), we get Helium (2 protons in the nucleus). During the fusion process, energy is released and shines outward from the center or core of this ball of gas. These giant balls of shining gas are called stars. So now that we have stars, solar systems, and galaxies, what out rocky planets? And what about the atoms other than hydrogen and oxygen? Where did they come from? Let’s return to the nuclear fusion going on inside a star’s core. At first the major fuel is hydrogen, which fuses to become helium. But if the star is large enough and hotenough, eventually the hydrogen and helium fuse to produce lithium (3 protons in the nucleus). Lithium fuses
with hydrogen to produce beryllium (4 protons in the nucleus). As more fusion occurs, more energy is produced.