ELS_MT_LESSON1_UNIVERSE AND SOLAR SYSTEM.pdf

FEU High School Earth and Life Science AY 2023-2024 LESSON 1: The Universe and the Solar system Objectives: At the end of the lesson, you should be able to: 1. state the different hypotheses explaining the origin...

FEU High School Earth and Life Science AY 2023-2024 LESSON 1: The Universe and the Solar system Objectives: At the end of the lesson, you should be able to: 1. state the different hypotheses explaining the origin of the universe; 2. describe the different hypothesis explaining the origin of the solar system. SUBJECT MATTER The Beginning of the Universe What is your idea of the beginning of the universe? All the star systems, galaxies, gases, and dusts, including all the matter and energy that exist at present, even those that existed in the past and will exist in the future, are contained in the universe. The study of the universe is called cosmology. Experts in this field who study the structure and changes in the present universe are called cosmologists. Creation Myths and Stories There were different theories that tried to explain the formation of the universe. In ancient times, most people tried to explain natural events as a result of the action of gods and spirits. A creation myth is a symbolic narrative of the beginning of the world as understood by a culture. These are handed down from generation to Figure 1.2 In the Bible, God created everything—from light to life—in six days. generation through oral traditions such as stories, poems, songs, works of art, and among others. Different cultures have their own creation myths. A popular example of this is the biblical account of creation written in the book of Genesis, where it says that God created everything in six (6) days (Figure 1.2). In the Tagalog mythology of Si Malakas at si Maganda, God (or Diyos in Tagalog) created the entire world by raising his hand then pointing them down. Shortly, the first man and woman appeared from inside a bamboo shoot. Ancient Egyptians believed in many gods and myths which narrate that the world arose from an infinite sea at the first rising of the sun. In India, there is the narrative that gods sacrificed Purusha, the primal man whose head, feet, eyes, and mind became the sky, earth, sun, and moon respectively. These are just some of the many examples of creation myths and stories passed down as a way of perpetuating the culture of a particular society. The ancient Greeks were among the first people to use systematic observation and reason to explain natural events. In fact, they were among the first ones to construct models of the entire universe. Aristotle and Ptolemy described a model of a universe that is geocentric. This model suggested that the Earth is at the center of the universe with the sun, moon, planets, and stars revolving around it. This model was later debunked by Galileo who discovered that the Earth is not the center of the universe using a telescope. Figure 1.3 The Geocentric Model of the universe 1|Page FEU High School Earth and Life Science AY 2023-2024 Theories on the Origin of the Universe We will discuss the four (4) scientific theories on the origin of the universe, namely: 1. Big Bang Theory 2. Steady State Theory 3. String Theory 4. M-Theory Big Bang Theory The Big Bang theory is the most accepted theory on the origin of the universe. So far, the details of this theory are consistent with the known laws of physics. You hear high pitch sound coming from a siren from an approaching fire truck or ambulance and the pitch drops as it passes Figure 1.4 Doppler effect as illustrated by a moving you or moving in other direction. This ambulance. The frequency decreases as it moves away and phenomenon is called the Doppler Effect increases as it moves towards the observer. (Figure 1.4). Waves, when coming from a moving source, decrease in frequency as it moves away and increase as it moves toward the observer. A similar phenomenon is also observed in light waves. In 1924, Edwin Hubble discovered that stars are not uniformly distributed in space, as seen by the Figure 1.5 Redshift—an illustration of how light also naked eye in the night sky. Instead, stars form decreases in frequency as it moves away from the source. clusters called galaxies. The distance of any galaxy from the Earth can be estimated by measuring the amount of light the galaxy emits. Through this, Hubble found out that nearly all galaxies tend to move away from the Earth. His evidence is based from the fact that the measured light from galaxies tends to move towards the red end (lower frequency) of the visible light spectrum, a phenomenon called redshift. If you look at Figure 1.5, the illustration of redshift is similar to that of the Doppler effect in the ambulance siren, implying a source that is moving away. With this observation, it was speculated that if the galaxies are moving away from us, there must have been some point in time when they must have been closer together in the past; they may have even come from a single point in the beginning. In 1927, George Lemaitre used this notion of an expanding universe to conceive the Big Bang theory. Figure 1.6 Georges The Big Bang theory states that about 13.7 billion years ago, everything Lemaitre – A Belgian in the universe started from an infinitely small, dense and hot entity astronomer and cosmologist who referred to as singularity. Where this singularity came from and why it formulated the modern expanded in the first place is still unknown. The theory today narrates Big Bang theory how the fundamental particles and forces molded the universe as we know it today. It is summarized as follows: 1. Inflation - the universe exponentially expanded from a singularity to about 1,035 meters in width. 2|Page FEU High School Earth and Life Science AY 2023-2024 2. Formation of the universe – as the universe expands, the four fundamental forces separated and the universe was made of elementary particles such as quarks, electrons, photons, and neutrinos. 3. Formation of proton and neutron - protons and neutrons were formed from quarks. 4. Nucleosynthesis – protons and neutrons combined to form the very first nuclei. One proton and one neutron became hydrogen; two protons and two neutrons became helium. 5. Radiation era – up to this time, the universe is dominated by radiation. Through time, this radiation is now in the form of cosmic microwave background. 6. Matter domination – at this point, electrons joined hydrogen and helium to form the very first atoms. 7. Birth of stars and galaxies – hydrogen and helium, which are gases, were produced in large quantities and formed large masses of gas clouds. Under gravity, they began to increase mass and ignite to produce stars. Multiple stars also began to cluster together through gravity to form galaxies. The Big Bang timeline includes the existence of the four (4) fundamental forces. These forces were speculated to be unified into a single force at very high temperature but separated when the temperature dropped. The four (4) fundamental forces include: 1. Strong force – Short-ranged (10-13 cm) attractive force which binds the nucleus. 2. Electromagnetic force – Long-ranged force that binds atoms which can either be attractive or repulsive. 3. Weak force – Short-ranged force present in radioactive decay. 4. Gravitational force – Weak, long-ranged, and attractive force which binds the solar system. Figure 1.7 Cosmic microwave background shows remnants of the Big Bang in a temperature range of ±200 microkelvins. What are the evidences for the Big Bang theory? As with any theory, there should be supporting evidence for it to become acceptable. Among these are the following: 1. Galaxies moving away – By determining the velocities of the galaxies based on the amount of light they emit, Hubble found out that nearly all galaxies are moving away, with the distance between distant galaxies increasing with time. If it was expanding, they must have been closer together in the past, and may even come from a single point at the beginning. 2. Presence of cosmic microwave background – in 1960, Arno Penzias and Robert Wilson discovered a background radio emission coming from every direction in the sky. This radiation was speculated as the remnant energy from the formation of the universe. This 3|Page FEU High School Earth and Life Science AY 2023-2024 energy probably dates back to the recombination era, when atoms were just beginning to form. 3. Abundance of Light Elements – Elements such as hydrogen, helium, with trace amounts of lithium, and beryllium found in the observable universe agree with the hypotheses of the Big Bang theory. Their abundance is checked from the spectra of the oldest stars and gas clouds. The ratios of these light elements match with what was expected from the big bang nucleosynthesis. Figure 1.8 The Inflation Theory proposes a period of exponential expansion of the universe during its first few moments. Although the Big Bang theory is the acceptable model of the origin of the universe because it can explain many observed features of the universe, there were still unresolved problems namely: flatness, monopole, and horizon. The Inflation theory proposed by Alan Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht offered solutions to the unresolved problems revolving the Big Bang theory. It proposed a period of exponential expansion of the universe prior to the more gradual big bang expansion, during which time the energy density of the universe was dominated by a cosmological constant type of vacuum energy that later decayed to produce the matter and radiation that fill the universe today. The inflation theory is regarded as an extension of the Big Bang theory. The table below summarizes the problems encountered by the Big Bang theory and the solutions offered by the inflation theory to address these problems. Problem Expectation (Big Reality (Observation Solution (Big Bang + Bang says…) says…) Inflation says…) Flatness The universe is curved The universe is nearly flat An exponential inflation according to sophisticated allows a very large curved measurements universe, but we can only observe the flat geometry. In the same way that the Earth is curved but, in our scale, we perceive it as flat Monopoles There should be heavy There are no magnetic An exponential inflation stable magnetic monopoles detected so far would have dramatically monopoles in the early decreased the temperature of universe because of the the expanding universe, no very high temperature longer allowing monopoles to form 4|Page FEU High School Earth and Life Science AY 2023-2024 Horizon The universe is about According to the math, the An exponential inflation 13.7 billion years old. observable universe is 93 faster than the speed of light Everything 13.7 billion billion light years across. How will allow these points to years ago must have can two points 93 billion light have been in contact 13.7 been in contact with years apart have been in billion years ago one another contact? Steady State Theory A theory opposing the Big Bang was proposed by Hermann Bondi, Thomas Gold, and Fred Hoyle in 1948. This theory states that though the universe is expanding, matter and energy density remains the same (Figure 1.9). The discovery of the cosmic microwave background (CMB) debunked this theory because we saw in Figure 1.7 that the universe is not constant in composition. String Theory What came before the Big Bang? To explain this, Figure 1.9 A comparison of the matter density of Big physicists needed a new theory that came from Bang and Steady State universe. Evidences suggest that combining the principles of Albert Einstein’s the amount of matter and energy in the universe is constant. Matter is diluted as space expands. general theory of relativity with the principles of quantum mechanics. In string theory, the assembly of particle type is replaced by a fundamental building block called a string, with dimensions confined to Planck length (roughly 1.6 X 10-35m). The string may come in two forms: open and closed. The strings are free to vibrate at different modes. The different vibrational modes may represent the different particle types – electron, photon, or even a graviton. A graviton is a particle carrying the force of gravity. The string theory Figure 1.10 The building block that replaces particles called is consistent with quantum gravity. It is able to describe interactions “strings” may come in open and of strings. It was at this point that there came great hope in the string closed forms. theory to finally unify all known forces and particles into a single “theory of everything”. M-Theory The string theory requires objects other than just strings. These objects may be seen as sheets or branes (membranes). Strings can attach to one or both ends of these branes. The M-theory considers 11 space-time dimensions. In the M-theory, the origin of the universe occurs as a result of the contact of two hyperdimensional branes. Stephen Hawking and Leonard Mlodinow argue Figure 1.11 The M-theory suggests that one or that the collision of M-branes leads to new universe. The both ends of the strings are attached to a sheet M-theory used by Hawking can allow for an infinite or branes. number of parallel universes which have the possibility of interphasing. 5|Page FEU High School Earth and Life Science AY 2023-2024 Theories on the Origin of the Solar System In the origin of the universe, there was an era when stars and galaxies began to form. A galaxy is defined as a gravitationally bound system of stars, stellar remnants, interstellar gas, and dark matter. Milky Way is one of the billion galaxies in the observable universe. The solar system is just one little speck in the Milky Way galaxy. The solar system is made up of one star (the Sun), together with the planets and other heavenly bodies surrounding it. Earth, the planet we live on, is part of the solar system. If we want to know how our planet was formed, we need to understand the origin and evolution of the solar system. There are many theories regarding the origin of the solar system, and we are going to describe them to help us understand how our solar system was formed. Descartes’ Vortex Theory French mathematician and physicist Rene Descartes was one of the first proponents of a model on the origin of the solar system. He postulated that the space was entirely filled with matter in various states, whirling around the sun. In his model (Figure 1.12), the system came into being by the vortex motion of solar materials. According to this model, the solar system was formed into bodies Figure 1.12 Descartes’ depiction of the Solar System run by interlocked with nearly circular orbits because of the whirlpool-like motion of vortices. pre-solar materials. He explained that the orbits of the planets are the primary whirlpool motion, and the satellites are the secondary whirlpool motion. Buffon’s Collision Theory Eighteenth century French naturalist George-Louis Leclerc, Comte de Buffon proposed that the planets were formed by the collision between the sun and a giant comet (Figure 1.13). The resulting debris formed into the planets that rotate in the same direction as they revolved around the sun. The theory however failed to explain the peculiar position of planets around the sun which are arranged in such a manner that the largest ones occupy the middle orbits Figure 1.13 The Buffon’s collision while the smaller ones occupied the marginal orbits. theory shows that planets were formed from the debris from the sun’s collision with a giant comet. Kant-Laplace’s Nebular Theory Based on the ideas of Descartes, Immanuel Kant and Pierre- Simon Laplace (Figure 1.14) proposed the nebular theory. The theory describes the formation of our solar system from a nebula cloud made from a collection of dust and gas. It is believed that the sun, planets, moon, and asteroids were formed around the same time around 4.5 billion years ago from a nebula. Figure 1.14 (L) Pierre-Simon Laplace (R) Immanuel Kant, the proponents of the Nebular Theory 6|Page FEU High School Earth and Life Science AY 2023-2024 According to this theory, the great cloud of gas and dust, referred to as nebula, began to collapse because of gravitational pull. As the cloud of gas and dust contracted, it spun more rapidly. Figure 1.15 Nebula collapses because of gravitational force, and contracts as it spins more rapidly. The spinning cloud flattened into a pancake-shaped object with a bulge at the center. As the nebula collapse further, local regions contracted on their own due to gravity. These regions became the sun and the planets. Figure 1.16 The spinning cloud of gas and dust flattened with bulges at the center which became sun and the planets. One major flaw of the theory is that it assumes that the sun should be spinning rapidly until now. It was found out, however, that the Sun is spinning more slowly than the planets. For their theory to be correct, either the Sun must be faster, or the planets must be slower. Jeans-Jeffreys’ Tidal Theory Sir James Hopwood Jeans and Harold Jeffreys suggested a dualistic theory in which the sun and planets were produced by different mechanisms. They proposed that the planets were formed from the substances that were torn out of the sun. Their model suggested that a massive star travelled near enough the sun and tear out some of its surface through gravitational attraction. Figure 1.17 A massive star travelled near enough the sun and These surface substances from the sun attracted surface substances through gravitational attraction. condensed and became protoplanets (lit. little These surface substances condensed and eventually attracted planets”). Eventually, they attracted other other bodies to form planets. bodies to form planets. 7|Page FEU High School Earth and Life Science AY 2023-2024 The Solar Nebular Theory The most convincing theory is the Solar Nebular Theory (SNT) because it follows the current known laws of physics and its mechanism allows the existence of exoplanets—planets outside the Solar System revolving around another star. Figure 1.18 Nebula is an interstellar cloud made Figure 1.19 Contraction in the dense region of a of gas and dust. nebula forms a protostar or protosun The solar system was formed as a result of the condensation of hydrogen gas and dust referred to as interstellar gas and dust cloud. An explosion of a star might have caused the gas and dust cloud to collapse, forming the sun and planets. The gas and dust collapsed due to the force of gravity. The center compressed through enough that it became a protostar, leaving the outer materials suspended around the center As the cloud continues to shrink, its rotational speed increases and becomes a rapidly rotating disk. The contraction converts gravitational energy into heat energy and causes the center to glow. When the temperature is enough, a nuclear reaction occurs at the core of the protostar, and later becomes the sun. Figure 1.20 The accretion of solar nebula forms Figure 1.21 The formation of planetesimals from which will planetesimals that will later combine with other grow into more massive objects becoming protoplanets objects to form protoplanets. and later become the planets. The remaining gas and dust cloud form disk-shaped bodies called solar nebulae due to rotation. According to the solar nebular theory, the formation of the planets involves different stages, in contrast to the single process of nebular theory. The first stage is the accretion of grain-sized particles to form centimeter-sized particles which would later grow to several kilometers in diameter. The objects formed are called planetesimals. The second stage involves the formation of more massive objects from coalescing planetesimal which is referred to as protoplanets and then later become the planets. 8|Page FEU High School Earth and Life Science AY 2023-2024 After the formation of the solar system, it was speculated that after a million years, it generated a strong solar wind that swept away all the gases left in the protoplanetary nebulae. As the protoplanet became large enough, its gravity pulled in the nebular gas. This resulted to the formation of the gas giants. Otherwise, the protoplanet would have remained in its rocky or icy state. Finally, the solar system is composed of only solid, protoplanetary bodies and gas giants. Eventually, after millions of years, the solar system ended up with planets that have stable orbits. Figure 1.22 The solar system is composed of rocky-icy planets and gas giants. Exploring the Solar System This era in Earth’s lifetime is significant for our growing curiosity. Astronauts were able to walk on the moon. Different space missions and planetary flyby were able to take photographs of farthest known bodies in the sky. We are able to watch a live feed of what is happening in space. Scientists and astronauts are able to manipulate their very own station in space, the International Space Station. Astronauts from different countries can now bring samples and conduct experiments in the station to determine the possibility of recreating Earth or discovering other livable planets in space. The solar system shows remarkable regularities in some of its observable properties. These regularities are observed in the motion and location of the planets’ and their satellites. Among these observed regularities are the following: 1. The orbits of all planets are almost in the same plane. 2. The orbits are elliptical rather than perfectly circular. 3. The plane of the orbits follows the Sun’s plane of rotation. 4. All planets revolve around the Sun counterclockwise. All planets except Venus and Uranus rotate counterclockwise. 5. The planets contain almost all the rotational motion of the Solar System. 6. The Solar System contains asteroids and comets. Figure 1.23 An asteroid Figure 1.24 The main asteroid belt found between the orbits of Mars and Jupiter. Aside from the sun, the eight (8) planets, and the four (4) dwarf planets, the solar system also contains heavenly bodies called asteroids and comets. Asteroids (Figure 1.23) are small, rocky heavenly bodies found between the orbits of Mars and Jupiter in a region called the asteroid belt (Figure 1.24). 9|Page FEU High School Earth and Life Science AY 2023-2024 Asteroids are sometimes referred to as minor planets in many ways, though they do not have an atmosphere, they orbit around the sun. They are thought of as remnants of the early stages of the solar system’s formation. They never formed as planets because of Jupiter’s high gravitational force. The first known asteroid is named Ceres. There are asteroids that can be perturbed out of the main asteroid belt and may especially come close to Earth. They are referred to as near-Earth asteroids (NEAs), The National Aeronautics and Space Administration (NASA) is monitoring these asteroids for any possibility of hitting our planet, which could have catastrophic consequences. Comets ate composed mainly of ice (frozen water and gas) and non-volatile dust (silicate minerals and carbon grains). They become active when their orbits take them near the sun. The sun’s heat causes the frozen gases to sublimate, forming vaporous jet of streams. These vapor jets create the comet’s tail. Comets originate from the two regions of the outer Figure 1.25 Halley’s comet solar system. The Kuiper belt, where short-period comets like Halley’s comet come from. Short- period comets orbit the sun in less than 200 years. The Oort cloud is located farther than the Kuiper belt and, has remained unexplored. Long-period comets are thought to originate from the Oort cloud and have orbits ranging from 200 years up to millions of years. Any object orbiting beyond Neptune is called a Trans-Neptunian Objects (TNO). Meteoroids are debris and remnants of dust from comets and asteroids. These small bodies are Figure 1.26 Kuiper Belt and the Oort Cloud found throughout the solar system and they glow brightly when their movement causes friction with the atmosphere as they are heated up. The trail formed by the burning meteoroid in the atmosphere is called a meteor or shooting star. Figure 1.27 Lyrid meteor shower which peaked April 22, 2020. 10 | P a g e FEU High School Earth and Life Science AY 2023-2024 Dwarf Planets The International Astronomical Union made a new classification of other celestial bodies in 2006. The IAU designated dwarf planets as objects that orbit the sun and have enough gravity to maintain a spherical shape but not capable of clearing smaller objects in the area of its own orbit and is not a satellite. In essence, the term is meant to designate any planetary-mass object that is neither a planet nor a natural satellite. There are five (5) celestial bodies that have been categorized as dwarf planet by IAU. These are: Makemake, Haumea, Ceres, Eris, and Pluto (Figure 2.16) Figure 1.28 The Dwarf Planets 1. Eris, the largest dwarf planet, is only slightly bigger than Pluto, it was discovered in 2003, Eris orbits at an average distance of 68 AU and takes 561.4 Earth years to orbit the sun. A day in Eris takes 25.9 hours and it has one moon, Dysnomia. 2. Pluto, discovered in 1930, has a diameter of 1,430 miles. It takes 247.9 Earth years to orbit the sun. Its day is 6.39 times as long as Earth’s. Pluto has five (5) known satellites: Charon, Nix, Hydra, Kerberos, and Styx. 3. Haumea was discovered in 2003. This dwarf planet has an extremely elongated shape. It rotates very rapidly and has the shortest day of all dwarf planets, 3.9 hours. It takes nearly 282 Earth years to complete one orbit. Its two (2) moons are: Hi’iaka and Namaka. 4. Makemake was discovered in 2005 and has no known satellites. It takes more than 305 Earth years to complete one revolution around the sun. A day in Makemake is 22.5 hours. 5. Ceres was first spotted by astronomers in 1801. It was first called a planet and later an asteroid. In 2006, it was reclassified as a dwarf planet. Ceres is the closest dwarf planet to Earth. Its year takes 4.6 Earth years and a day in Ceres is 9.1 hours. It has no known satellites. 11 | P a g e FEU High School Earth and Life Science AY 2023-2024 Figure 1.29 The 8 Planets that revolve around the Sun The eight (8) planets are grouped into two (2) categories based on composition: terrestrial and Jovian. Terrestrial planets are composed mainly of dense, rocky, and metallic materials. They are also referred to as the inner planets when we talk about their position relative to the sun. The terrestrial, inner planets include Mercury, Venus, Earth, and Mars. The Jovian Planets on the other hand, are composed mainly of gases such as hydrogen and helium. Hence, they are also called the gas giants. In terms of their position relative to the sun, they are referred to as the outer planets. The Jovian, outer planets include Jupiter, Saturn, Uranus, and Neptune. Formative Assessment DIRECTIONS: In no more than 5 sentences, answer the following questions: 1. What is the premise of the Big Bang theory? What are the evidences that support the theory? 2. What are the significant assumptions of the inflation theory? What evidence supported the inflation theory? 3. Based on the string theory, describe the characteristics of strings. 4. How did the M-theory explain the origin of the universe? 5. What is the fate of the universe? Will the universe continue to expand, or will it eventually contract because of gravity? 6. Is the solar system unique or rare? What is the possibility of finding a similar system within the Milky Way Galaxy? What about an Earth-like planet? 12 | P a g e