Started with a Bang: Origin & Structure of the Earth PDF

SH1631 Started with a Bang sized origin to astronomical scope. The expansion has apparently Origin and Structure of the Earth continued, but much more slowly, over the ensuing b...

SH1631 Started with a Bang sized origin to astronomical scope. The expansion has apparently Origin and Structure of the Earth continued, but much more slowly, over the ensuing billions of years. Scientists cannot be sure exactly how the universe evolved after the big bang. Many believe that as time passed and matter cooled, more diverse kinds of atoms began to form, and they eventually condensed into the stars and galaxies of our present universe. Figure 1. The oldest known planet identified Source: https://www.nasa.gov/multimedia/imagegallery/image_feature_76.html The most popular theory of our universe’s origin centers on a cosmic cataclysm unmatched in all of history—the Big Bang. This theory was Figure 2. Georges Lemaitre Source: www.findagrave.com Figure 3. Edwin Hubble Source: www.stsci.edu born of the observation that other galaxies are moving away from our own at high speed, in all directions, as if they had all been propelled Origins of the Theory by an ancient explosive force. A Belgian priest named Georges Lemaitre first suggested the Big Before the big bang, scientists believe, the entire vastness of the Bang Theory in the 1920s when he theorized that the universe began observable universe, including all of its matter and radiation, was from a single primordial atom. The idea subsequently received compressed into a hot, dense mass just a few millimeters across. This significant boosts by Edwin Hubble’s observations that galaxies are nearly incomprehensible state is theorized to have existed for only a speeding away from us in all directions, and from the discovery fraction of the first second of time. of cosmic microwave radiation by Arno Penzias and Robert Wilson. Big bang proponents suggest that some 10 billion to 20 billion years The glow of cosmic microwave background radiation, which is found ago, a massive blast allowed all the universe’s known matter and throughout the universe, is thought to be a tangible remnant of leftover energy—even space and time themselves—to spring from some light from the big bang. The radiation is something that is used to ancient and unknown type of energy. The theory maintains that in an transmit TV signals via antennas, but it is the oldest radiation known instant—a trillion-trillionth of a second—after the big bang, the and may hold many secrets about the universe’s earliest moments. universe expanded with incomprehensible speed from its pebble- 01 Handout 1 *Property of STI  [email protected] Page 1 of 8  SH1631 The Big Bang Theory leaves several major questions unanswered. Our universe burst into existence in an event known as the Big Bang One is the original cause of the Big Bang itself. Several answers have 13.8 billion years ago. Moments later, space itself ripped apart, been proposed to address this fundamental question, but none has expanding exponentially in an episode known as inflation. Tell-tale been proven—and even adequately testing them has proven to be a signs of this early chapter in our universe’s history are imprinted in the formidable challenge. skies, in a relic glow called the cosmic microwave background. Recently, this basic theory of the universe was again confirmed by the NASA Technology Views Birth of the Universe Planck satellite, a European Space Agency mission for which NASA provided detector and cooler technology. But researchers had long sought more direct evidence for inflation in the form of gravitational waves, which squeeze and stretch space. “Small, quantum fluctuations were amplified to enormous sizes by the inflationary expansion of the universe. We know this produces another type of waves called density waves, but we wanted to test if gravitational waves are also produced,” said project co-leader Jamie Bock of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., which developed the BICEP2 detector technology. Bock has a joint appointment with the California Institute of Technology, also in Pasadena. The gravitational waves produced a characteristic swirly pattern in polarized light, called “B-mode” polarization. Light can become polarized by scattering off surfaces, such as a car or pond. Polarized sunglasses reject polarized light to reduce glare. In the case of the cosmic microwave background, light scattered off particles called Astronomers are announcing today that they have acquired the first electrons to become slightly polarized. direct evidence that gravitational waves rippled through our infant universe during an explosive period of growth called inflation. This is The BICEP2 team took on the challenge of detecting B-mode the most reliable confirmation yet of cosmic inflation theories, which polarization by pulling together top experts in the field, developing say the universe expanded by 100 trillion times, in less than the blink revolutionary technology, and traveling to the best observing site on of an eye. The findings were made with the help of NASA-developed Earth at the South Pole. The collaboration includes major detector technology on the BICEP2 telescope at the South Pole, in contributions from Caltech; JPL; Stanford University, Stanford, Calif.; collaboration with the National Science Foundation. Harvard University, Cambridge, Mass.; and the University of Minnesota, Minneapolis. “Operating the latest detectors in ground-based and balloon- borne experiments allows us to mature these technologies for space As a result of experiments conducted since 2006, the team has been missions and, in the process, make discoveries about the universe,” able to produce compelling evidence for the B-mode signal, and with said Paul Hertz, NASA’s Astrophysics Division director in Washington. it, the strongest support yet for cosmic inflation. The key to their success was the use of novel superconducting detectors. 01 Handout 1 *Property of STI  [email protected] Page 2 of 8  SH1631 Superconductors are materials that, when chilled, allow electrical How Did the Sun and Planetary System Form? current to flow freely, with zero resistance. “Our technology combines the properties of superconductivity with tiny structures that can only be seen with a microscope. These devices are manufactured using the same micro-machining process as the sensors in cell phones and Wii controllers,” said Anthony Turner, who makes these devices using specialized fabrication equipment at JPL’s Microdevices Laboratory. The B-mode signal is extremely faint. To gain the necessary sensitivity to detect the polarization signal, Bock and Turner developed a unique array of multiple detectors, akin to the pixels in modern digital cameras, but with the added ability to detect polarization. The whole detector system operates at a frosty 0.25 Kelvin, just 0.45 degrees Figure 4. Nicolaus Copernicus in the 1000 Zloty bill of Republic of Poland Source: www.tcocd.de Fahrenheit above the lowest temperature achievable, absolute zero. The sun and the celestial bodies that revolve around it, including the “This extremely challenging measurement required an entirely planets with their satellites, comets, and meteors, comprise the Solar new architecture,” said Bock. “Our approach is like taking a camera System. Before Nicolaus Copernicus described the modern and building it on a printed circuit board.” heliocentric or sun-centered system of planetary motions in 1543, the Earth has been assigned the central place in the universe. The most The BICEP2 experiment used 512 detectors, which sped up enduring arrangement of this geocentric Earth-centered plan was the observations of the cosmic microwave background by 10 times over Ptolemaic System. Copernicus, however, placed the planets in the team’s previous measurements. Their new experiment, already circular paths around the sun and put the Earth as the sixth planet with making observations, uses 2,560 detectors. These and future its satellite, the moon. experiments not only help confirm that the universe inflated dramatically but are providing theorists with the first clues about the On the other hand, some scientists continued studying the origin of exotic forces that drove space and time apart. The results of this study the solar system. They have formulated theories to prove and explain have been submitted to the journal Nature. JPL is managed by the the origin of the solar system. California Institute of Technology in Pasadena for NASA. In 1755, a German philosopher, Immanuel Kant, and a French mathematician, Laplace, in 1796 published closely related hypotheses, which postulated that the solar system was derived from the condensation of an enormously dispersed gaseous atmosphere surrounding the sun. The increased rotational velocity of this atmosphere during condensation was assumed to have produced a discoidal shape, the plane of the disk coinciding with that of the sun’s equator. When velocity reached a critical point, centrifugal force would throw off part of the gas as a ring and materials of each ring gradually assembled into a gaseous globe, which eventually became a solid planet revolving around the sun in a circular orbit like that of the ring 01 Handout 1 *Property of STI  [email protected] Page 3 of 8  SH1631 planets. The smaller bodies became asteroids, meteors, and satellites of planets. Another theory was formulated by the German physicist Carl Friedrich von Weizacken and U.S. chemist Harold C. Urey, called the Dust Cloud Theory, in 1945. The nebula was assumed to have a composition mainly of hydrogen and helium, like the sun, with only 1% of heavier elements. The mass of this “Dust Cloud” was originally 10% of the sun’s mass or about a hundred times as great as the present combined mass of the planets and satellites. The nebula was much flattened by its rotation, which as of the planetary type, in that the gas molecules moved faster as they were closer to the sun. Interactions of the gas molecules accelerated the lighter ones so that they mostly escaped from the nebula. The interactions also produced swirls, forming lumps in the nebula that could grow to become planets and satellites. Another hypothesis, the Protoplanet Hypothesis, was proposed in 1949 by Gerald P. Kuoper. It states that the original nebula was so massive that on further contraction and flattening, it broke into separate clouds or protoplanets. These remained stable in the tidal field of the sun. As they contracted, they developed denser cores surrounded by large atmospheres of the lighter gases. Later the shrinking primitive sun became hot enough to emit powerful corpuscular and ultraviolet radiation. The radiations drove away into Figure 5. Nebula Theory space remnants of the nebula and the vast atmosphere of the planets, Source: science.howstuffworks.com which thus looked like a swarm of comets with tails. This hypothesis proposed a process that could have developed planetary systems from which it was formed. While these gaseous globes were around many stars. Indeed, it has been surmised that the majority of contracting, most of them abandoned the rings, which assembled into yellow stars, like the sun, may possess systems of planets. satellites revolving in circles around these planets. The solar system where the Earth belongs is just a small part of the Thus, according to the hypothesis called the Nebular Hypothesis (see vastness that we call the universe. No one knows its boundaries nor Figure 5), the solar system developed with the observed regularities its origin. Did it originate suddenly in an enormous explosion, or has it in its motions. When other discrepancies seemed to invalidate the been in the process of creation without a definite beginning or end? hypothesis of rotational instability, a second theory, the Planetesimal What were mentioned above are just theories which need to be Theory, was formulated. It supposed that the planetary system was proven. formed from materials removed from the sun by tidal action caused by a passing star. The projection became masses of gases that revolved around the sun. The larger bodies attracted smaller ones and became 01 Handout 1 *Property of STI  [email protected] Page 4 of 8  SH1631 Structures and Subsystems of the Earth Mantle The Earth, much like any other planet in the solar system, is built upon The dense layer of the Earth composed only of molten silicate by several layers of materials left behind during the stellar formation rocks. It is always in perpetual convection motion due to the of the sun. As theorized, the heavier materials remained and accreted core heating it. The physical characteristics of the mantle vary to form the terrestrial planets -- Mercury, Venus, Earth, and Mars. The with depth. Near the surface, to a depth of about 100 lighter materials made the gas giants -- Jupiter, Saturn, Uranus, and kilometers, the outermost mantle is cool, strong, and hard. In Neptune. contrast, the layer below 100 kilometers is so hot that the rock is weak, soft, plastic, and flows slowly-like cold honey. Even The Earth has several structures that give its shape and form. You can deeper, pressure overwhelms temperature, and the mantle refer to the diagram below. rock becomes strong again. Due to its behaving as both solid and liquid, many believe that the mantle might be a non- Newtonian fluid. Core The hottest layer of the Earth, and the source of the Earth’s magnetic field. It has two (2) layers, both made from iron and nickel. The liquid outer core stands as the boundary between the mantle and the main (or inner) core, which is a molten, solid material. The Earth is comprised of four parts, namely Lithosphere, Hydrosphere, Biosphere, and Atmosphere. Their names are derived from the Greek words for stone (litho), water (hydro), air (atmo), and life (bio). Lithosphere The lithosphere is basically the rocky crust of the Earth. It is inorganic and is composed mainly of different kinds of minerals. This is the outer part of the Earth, including both the uppermost mantle and the crust. The mantle surrounds the core and lies beneath the crust. Figure 6. The Earth’s structure Source: https://upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Earth-crust-cutaway-english.svg/800px-Earth- crust-cutaway-english.svg.png Hydrosphere This is composed of all the waters, which circulates in the Earth. This The structure is as follows: includes the oceans, seas, rivers, lakes, and even the moisture in the Crust air. Oceans cover 71 percent of Earth, and its currents transport heat This is the brittle outermost layer of the planet. Due to the across vast distances, altering global climate. various landforms and processes it undergoes, it has a variable thickness ranging from five (5) to 10 km from ocean Atmosphere basins to 25 to 70 km from the continents. The atmosphere is the mass of air surrounding our planet. It is subdivided into different layers of different densities. The air of Earth is comprised of 79% Nitrogen and fewer than 21% Oxygen. The 01 Handout 1 *Property of STI  [email protected] Page 5 of 8  SH1631 remaining amount is shared by Carbon Dioxide and other forms of organisms are all part of the biosphere. The biosphere includes the gases. The atmosphere is held to Earth by gravity and thins rapidly uppermost geosphere, the hydrosphere, and the lower parts of the with altitude. Ninety-nine percent is concentrated in the first 30 atmosphere. Sea life concentrates near the surface, where sunlight is kilometers, but a few traces remain as far as 10,000 kilometers above available. Plants also grow on Earth ’s surface, with roots penetrating the Earth’s surface. a few meters underground. Large populations of bacteria live in rocks to depths of as much as 4 kilometers, some organisms live on the The atmosphere supports life because animals need oxygen, and ocean floor, and a few windblown microorganisms drift at heights of plants need both carbon dioxide and oxygen. Also, the atmosphere 10 kilometers or more. But even at these extremes, the biosphere is a supports life indirectly by regulating the climate. Air acts as both very thin layer at Earth ’s surface. Plants and animals are affected by blanket and a filter, retaining heat at night and shielding us from direct the Earth ’s environment. Organisms breathe air, require water, and solar radiation during the day. Wind transports heat from the equator thrive in a relatively narrow temperature range. Terrestrial organisms toward the poles, cooling equatorial regions, and warming ultimately depend on soil, which is part of the geosphere. Less temperature and polar zones. obviously, plants and animals also alter and form the environment they live in. For example, living organisms contributed to the evolution of Biosphere the modern atmosphere. These subsystems interact with each other and influence the climate, trigger geological processes, and affect life all over the Earth. The Characteristics of Earth that are Necessary to Support Life Habitable Zone. Retrieved from www.cab.inta-csic.es There are a few key ingredients that scientists often agree are needed Figure 7. Subsystems of the Earth for life to exist — but much debate remains as to what limits there Source: cladenver.esfaculty.ucdu actually might be on life. Even Earth hosts some strange creatures The biosphere comprises of all living organisms, from the smallest that live in extreme environments. Here is what makes life able to bacteria to the largest whale. Plants, animals, and single-celled 01 Handout 1 *Property of STI  [email protected] Page 6 of 8  SH1631 thrive on our home planet (and likely for alien life to arise on other Energy worlds). Second, life needs energy. Without energy, virtually nothing would happen. The most obvious source of energy is a planet or moon’s host Water star, as is the case on Earth, where sunlight drives photosynthesis in “First, you’d need some kind of liquid, any place where molecules plants. The nutrients created by photosynthesis, in turn, are what the can go react,” Seager told OurAmazingPlanet. In such a soup, the bulk of life on Earth directly or indirectly relies on for fuel. Still, ingredients for life as we know it, such as DNA and proteins, can swim countless organisms on Earth subsist on other sources of energy as around and interact with each other to carry out the reactions needed well, such as the chemicals from deep-water vents. There may be no for life to happen. shortage of energy sources for life to live off. The most common contender brought up for this solvent is the one life Time uses on Earth: water. Water is an excellent solvent, capable of Scientists have argued that habitable worlds need stars that can live dissolving many substances. It also floats when it is frozen, unlike at least several billion years, long enough for life to evolve, as was the many liquids, meaning that ice can insulate the underlying fluid from case on Earth. Some stars only live a few million years before dying. freezing further. If water instead sunk when frozen, this would allow Still, “life might originate very fast, so age is not that important,” another layer of water to freeze and sink, and eventually, all the water astrobiologist Jim Kasting at Pennsylvania State University told would get frozen, making the chemical reactions behind life OurAmazingPlanet. impossible. For instance, the Earth is about 4.6 billion years old. The oldest known Astronomers looking for extra-terrestrial life most often focus on organism first appeared on Earth about 3.5 billion years ago, meaning planets in the so-called habitable zones of their stars — orbits that are that life might conceivably evolve in 1.1 billion years or less. However, neither too hot nor too cold for liquid water to persist on the surfaces more complex forms of life did take longer to evolve — the first of those worlds. Earth happened to hit the Goldilocks mark, forming multicellular animals did not appear on Earth until about 600 million within the sun’s habitable zone. Mars and Venus lie outside it; if years ago. Because our sun is so long-lived, comparatively, higher Earth’s orbit had been just a bit further inside or outside of where it is, orders of life, including humans, had time to evolve. life may likely never have arisen, and the planet would be a cold desert-like Mars or a cloudy furnace-like Venus. Recycling Other researchers have suggested that plate tectonics is vital for a Of course, alien life may not play by the rules we are used to on Earth. world to host life — that is, a planet whose shell is broken up into Astrobiologists increasingly suggest looking beyond conventional plates that continuously move around. habitable zones. For instance, while liquid water might not currently persist on the surface of Mars or Venus, there may have been a time “People talk about plate tectonics as essential in recycling when it did. Life might have evolved on their surfaces in that time, and molecules life needs,” Seager said. then either fled to safer locales on those planets, such as underground, or adapted to the environment when it became harsh, For instance, carbon dioxide helps trap heat from the sun to keep the much as so-called extremophile organisms have on Earth, or both. Earth warm. This gas gets typically bound up in rocks over time, meaning the planet would eventually freeze. Plate tectonics helps Besides, other solvents might host life. “Saturn’s moon, Titan, has ensure this rock gets dragged downward, where it melts, and this liquid methane and ethane,” Seager said. molten rock finally releases this carbon dioxide gas back into the atmosphere through volcanoes. 01 Handout 1 *Property of STI  [email protected] Page 7 of 8  SH1631 “Plate tectonics is useful but probably not imperative,” Kasting The planet’s orbit must be circular and stable enough to keep it at said. Seager agreed, saying that “volcanism might very well provide a proper distance and prevent drastic seasonal changes. enough fresh supplies of whatever life might need.” The planet’s gravity must be strong enough to hold a substantial atmosphere. Bonus Features Other factors researchers have trotted out for why life succeeded on References: Earth include how little variation there is in our sun’s radiation Braganza, M. C. (1997). Earth Science. Quezon City: Rex Printing compared with more volatile stars, or how our planet has a magnetic Company. field that protects us from any storms of charged particles from the Choi, C. Q. (2012, October 18). What Makes Earth So Perfect for sun. Violent bursts of radiation could have scoured life from Earth in Life? Lifted and modified from its early, fragile stages. http://www.livescience.com/31788-why-Earth -perfect-for- life.html Still, “people are constantly rethinking each of these things and how Origin of the Universe. (n.d.). Lifted and modified from important they are,” Seager said. “We’re trying to be less conservative http://science.nationalgeographic.com/science/space/univers and more open-minded. We want to learn about what gray areas might e/origins-universe-article/ exist for possible life.” NASA Technology Views Birth of the Universe (2014). Lifted and modified from Earth remains the only known planet to host life, due to a unique http://www.jpl.nasa.gov/news/news.php?release=2014-082 combination of factors. However, continued monitoring of alien worlds British Geological Survey (n.d.). The structure of the Earth. Lifted and might one day change that, by finding other planets that share these modified from attributes or by discovering different ways that life has found to https://www.bgs.ac.uk/discoveringGeology/hazards/earthqua blossom in the universe. kes/structureOfEarth.html Habitable Planets Even if planets exist near some other stars, there is no guarantee that they are livable. Astronomers have proposed several conditions needed to make a planet habitable: The central star should not be more than 1.5 Mo (Solar mass) so that it will last long enough for substantiated life to evolve at least 2 billion years and will not kill evolving life with too much UV radiation, which breaks down organic molecules. The central star should be at least 0.3 Mo to be warm enough to create a large orbital zone in which a planet could retain liquid water. The central star should not flare violently or emit intense x-rays. It should be on the main sequence to be stable, long enough to give its planet long-term climatic stability. The planet must orbit at the right distance from the star so that liquid water will neither evaporate nor permanently freeze. 01 Handout 1 *Property of STI  [email protected] Page 8 of 8