Earth And Life Science Grade 11/12 Nebular Theory and Encounter Theory Study Guide PDF

Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System LESSON 1.3 Nebular Theory and Encounter Theory Table of Contents Introduction...

Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System LESSON 1.3 Nebular Theory and Encounter Theory Table of Contents Introduction 1 Learning Competency 2 Learning Objectives 2 Warm-Up 3 Learn about It 5 Description of the Nebular Theory 5 Cloud Collapse 6 Formation of Protoplanetary Disk 7 Growth of Planets 9 Proponents of the Nebular Theory 10 Drawbacks of the Nebular Theory 10 Description of the Encounter Theory 11 The Planetesimal Theory 11 Proponents of the Planetesimal Theory 12 Drawbacks of the Planetesimal Theory 12 The Tidal Theory 13 Proponents of the Tidal Theory 13 Drawbacks of the Tidal Theory 13 Key Points 14 Check Your Understanding 15 Bibliography 17  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Lesson 1.3 Nebular Theory and Encounter Theory The huge cloud of dust and gas surrounding this stellar nursery called the Orion Nebula will one day become hot enough to ignite fusion or combination for a star to be born. Introduction Have you played Legos when you were a kid or seen kids playing Lego bricks? How about Minecraft? How do playing Minecraft and building with Lego bricks work? Both of them allow us to build anything by combining or breaking apart some blocks. Did you know that there 1  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System are theories regarding the origin of the universe that work similarly in this manner? The nebular theory suggests that stars originated from the combination of dust and gases. On the other hand, the encounter theory suggests that planets were formed from materials that broke off another celestial body, much like how we put together or break apart Lego bricks or blocks in Minecraft. But, specifically, how did the combination of cosmic materials form the stars? And how did the breaking apart of a star result in the formation of planets? Learning Competency At the end of this lesson, the given enrichment competency should be met by the students. Compare the different hypotheses explaining the origin of the Solar System. Learning Objectives In this lesson, you should be able to do the following: Explain the origin of the solar system according to the nebular and encounter theories. Describe the contributions of the proponents of these theories. Discuss the negative implications of these theories. 2  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Warm-Up Modeling Accretion Materials student role cards ○ interstellar dust card (red for metallic grains, blue for icy grains, and yellow for rocky grains) ○ planetesimal card ○ protoplanet card 3  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Procedure 1. This activity is best done with your classmates in a large space or area. 2. Each one of you must have a different interstellar dust card from one another (metallic, icy, and rocky). 3. Form a big circle with your classmates and assign someone to stand in the middle. He/She represents the sun. First Round 4. The goal of the game is to tag your classmates with the same role card as yours. You cannot tag your classmates with a different type of role card. For example, if you have a metallic grains card, you can only tag other students with the same role card. You cannot tag students with icy or rocky grains cards. 5. Before the game starts, keep these reminders in mind. First, everyone should move in a counterclockwise circular path around the sun. One of you will act as the sun in the middle. Second, everyone should only jog as they move around. You are not allowed to run. Third, the arms should only stay at the sides as you jog around. 6. Start tagging your classmates with the same role card as yours. If you are tagged, you should move together with the person who tagged you. 7. After several minutes, stop tagging others. 8. The winner of this round is the group who formed the largest clump. Second Round 9. Students formed in clumps can now tag other students in clumps as well. However, only those with the same role card can be tagged and grouped. 10. After several minutes, stop tagging others. 11. The winner of this round is the group who formed the largest clump. 12. Each clump of interstellar dust will be given another card with “planetesimal” written on it. Students in this stage simulated the first stage of solar system formation. Third Round 13. Each planetesimal can now tag other planetesimals with a different role card. For example, a planetesimal consisting of a group of metallic grains can now tag 4  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System planetesimals consisting of rocky or icy grains. 14. The final winner is the one with the largest group. 15. Hand out a protoplanet role card to the planetesimal group with different interstellar dust. Extra Round 16. This extra round is for your teacher, with a role as a passing star. 17. Your teacher will try to carefully bump or pass a group/s and push some students away from the group. 18. The students who are pushed away will form their own small groups. Guide Questions 1. What happens in the interstellar dust in the first round of the activity? 2. What is the difference between interstellar dust, planetesimals, and protoplanets in the activity? 3. What are the differences between the first stage and second stage of star formation that are represented by the second and third round respectively? 4. When the teacher passed a clump and pushed away some members, what do you think these members formed? 5. Rounds 1 to 3 and the extra round simulate the basic concept of two of the theories regarding the origin of the universe. Which rounds of the activity do you think simulate nebular and encounter theory? Learn about It Description of the Nebular Theory Another theory that explains the origin of the solar system is the nebular theory. From the term itself, "nebula" means cloud. This indicates that stars originate from interstellar gas and dust. The shift from undifferentiated cloud to whole solar system formation complete with planets, moons, and stars takes approximately a hundred million years. 5  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System There are three major steps on how the solar system was formed according to nebular theory. These are cloud collapse, formation of the protoplanetary disk, and growth of planets. Essential Question How did the solar system form according to the nebular theory? Cloud Collapse The origin of the planets and sun in the solar system is a huge cloud of molecular gas and dust. Then, something occurred that made the cloud collapse. Possible reasons are shockwaves from a supernova or the effect of a passing star. Whatever the reason, the result was a collapse at the center of the cloud due to gravity. As shown in Fig. 1, the collapsing of the cloud makes it spin faster. Fig. 1. Cloud collapse Have you ever watched a skating competition? One of the tricks of the contestant that amazes people is when they spin so fast without falling. If you are a keen observer, they can only do the trick if they bring in their arms. Extending their arms while attempting to spin 6  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System fast will result in a failure of the act. As shown in Fig. 2, this is possible because rotational velocity is inversely proportional to the radius. Fig. 2. Relationship of radius and rotational velocity In relation to the nebular theory, the collapsed cloud of interstellar gas and dust results in a smaller radius which means it will spin faster. This resulted in a flattened disk of cloud with a central bulge. Remember As the radius decreases, the rotational velocity increases. Therefore, a collapsed nebula spins at a higher rate. Formation of Protoplanetary Disk Metals and silicates could exist near the sun because these compounds have higher boiling points. As a result, terrestrial planets including Mercury, Venus, Earth, and Mars were eventually formed containing a high concentration of these compounds. The terrestrial 7  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System planets could not grow in huge diameters because of the limited reserve of metallic elements in the solar nebula. Fig. 3. Terrestrial planets. From left to right: Mercury, Venus, Earth, and Mars; the last one on the right is Ceres, the terrestrial dwarf planet Jovian planets composed of Jupiter, Saturn, Uranus, and Neptune are huge planets made up of gases without land surfaces. These planets were formed farther from the sun because the temperature is cool enough for the gases to condense, forming these massive, but low-density planets. Fig. 4. Jovian planets. From left to right: Jupiter, Saturn, Uranus, and Neptune 8  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Fig. 5. The formation of a protoplanetary disk in nebular theory Growth of Planets As shown in Fig. 6, dust and grains surrounding the sun eventually formed clumps. These clumps then accreted forming planetesimals. Planetesimal is a small celestial body that once collides together, it tends to fuse to form the planets of the solar system. Fig. 6. Growth of planets in the nebular theory 9  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Proponents of the Nebular Theory The nebular theory is credited to Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. Emmanuel Swedenborg Immanuel Kant Pierre-Simon Laplace (1688–1772) (1724–1804) (1749–1827) Fig. 7. The proponents of the nebular theory Drawbacks of the Nebular Theory One problem of the nebular theory is that it assumes that dust particles will be attached to each other forming a planet. However, this is not true for Saturn because the particles surrounding it repel each other. Another problem is that it does not follow the law of angular momentum. If it does, the sun should be spinning at a higher rate than the others. Moreover, this theory did not consider Uranus and Venus, which rotates in a clockwise direction. This is opposing the counterclockwise rotation of other planets. If this theory is correct, all the planets should be moving in the same direction. 10  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Description of the Encounter Theory The encounter theory proposes that the planets were formed from the material ejected from the sun during an encounter with another celestial object. This celestial object could have been another star. The encounter theory has several forms, including the planetesimal theory and the tidal theory. Essential Question How did the planets form according to the encounter theory? Fig. 8. The encounter theory proposes that the planets formed from the material ejected from the sun during an encounter with another star. The Planetesimal Theory According to the planetesimal theory, a passing star termed an intruding star nearly collided with the protosun. The massive gravitational pull of the intruding star causes the protosun to eject filaments of material. These materials condensed into planetesimals from which the planets were formed through accretion. Unlike the nebular theory that describes Earth starting from molten mass, the planetesimal theory describes Earth starting from a solid mass smaller than its present size. The oceans and the atmosphere were formed on Earth through volcanic activities. 11  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Proponents of the Planetesimal Theory The planetesimal theory was proposed by an American geologist, Thomas Chrowder Chamberlin, and an American astronomer, Forest Ray Moulton in 1905. Moulton started working with Chamberlin when he took graduate studies in Chicago. As opposed to what Kelvin proposed on the age of Earth, Chamberlin realized that Earth was older. He proposed that the accretion of minute solid particles created planets and their moons rather than by gaseous or liquid material condensation. However, Moulton provided mathematical calculations to Chamberlin’s idea making it into a solid theory. Thomas Chrowder Chamberlain Forest Ray Moulton (1843–1928) (1872–1952) Fig. 9. The proponents of the planetesimal theory Drawbacks of the Planetesimal Theory This theory is no longer accepted today due to the fact that hot material from the sun expands and dissipates rather than contracts. In addition, the force from the passing star will pull dust and gases far away from the sun, so that they would not be able to form the planets in the solar system. 12  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System The Tidal Theory The tidal theory explains that the solar system formed as a result of a near collision between a passing star and the sun. However, unlike the planetesimals theory, the tidal theory proposed that the hot gas from the passing star condensed into planets instead of condensing into planetesimals. When the star passed near the sun, the gravitational attraction pulled the mass of dust and gas from the remaining nebula around the sun. The gas particles are then condensed into liquid and solid states. The particles clump together to form cosmic bodies of different sizes. These bodies are further condensed into planets. Therefore, the interaction between the gravity of the passing star and the sun led to the formation of the planets in the solar system. The materials closer to the sun are denser. This explains the positions of the terrestrial planets near the sun. In contrast, the materials from the passing star are less dense; thus, explaining the positions of the Jovian planets. Remember Unlike the planetesimals theory, the tidal theory proposed that the hot gas from the passing star condensed into planets instead of condensing into planetesimals. Proponents of the Tidal Theory The tidal theory was proposed by James Jeans, an English physicist and astronomer, and Harold Jeffreys, an English mathematician and astronomer. In 1916, Jeans first postulated that the interaction between the sun and an intruding star would create a bulge of dust and gasses around the primitive sun. The bulge would then condense to create the protoplanets. In 1929, Jeffreys suggested some modifications and made it more relevant to the increasing knowledge of cosmogenic ideas in the 20th century. He proposed that the passing star was so massive that it pulled out materials from the sun. As the star got farther from the sun, the debris was left in the gravitational range of the sun. Drawbacks of the Tidal Theory The tidal theory, because of its simplicity, was popular until the first half of the 20th century. 13  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System One criticism of the tidal theory that made it no longer accepted in the modern era is that the ejected hot materials from a star cannot contract or condense but will only dissipate in space. It is because only metal and rock materials could condense or solidify. Thus, planets will not form. In addition, critics claimed that the encounter of a star with the sun is a remote possibility because of the vastness of the universe. Key Points Nebula means cloud. This indicates that stars originate from interstellar gas and dust according to the nebular theory credited to Swedenborg, Kant, and Laplace. ○ There are three major steps on how the solar system is formed according to nebular theory. Cloud Collapse: The origin of the planets and sun in the solar system is a huge cloud of molecular gas and dust that collapsed. Formation of the Protoplanetary Disk: Materials from the collapsed cloud fall inward and flatten into a disk. Growth of Planets: Dust and grains surrounding the disk collide and form planetesimals that collect into a planet. The encounter theory proposed that the planets formed from the material ejected from the sun during an encounter with another celestial object. It has several forms, including the planetesimal theory and the tidal theory. ○ The planetesimal theory, proposed by Chamberlin and Moulton, describes Earth starting from a solid mass smaller than its present size. It is no longer accepted today due to the fact that hot material from the sun will expand and dissipate rather than contract. ○ The tidal theory by Jeans and Jeffreys proposed that the hot gas from the passing star condensed into planets instead of condensing into planetesimals. One problem of the tidal theory is that the hot material from either star cannot contract. Thus, planets will not form. 14  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Check Your Understanding A. Complete the following flowchart. Choose the letter of the correct answer in the choices below. A. Interstellar cloud (nebula) F. Accretion B. Protoplanetary disk G. Terrestrial planets C. Protosun H. Jovian planets D. Sun I. Asteroids E. Gases, ice J. Comets 15  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System B. Arrange the following events in order. Write numbers 1 to 5 on the blanks provided. Planetesimal theory __________ Materials ejected from the protosun condensed into planetesimals. __________ The oceans and the atmosphere were formed on Earth through volcanic activities. __________ The planets are formed by accretion. __________ The protosun ejects filaments of materials. __________ An intruding star nearly collided with a protosun. Tidal theory __________ The cosmic bodies condensed into planets. __________ The gravitational attraction pulled the mass of dust and gas from the remaining nebula around the sun. __________ The particles clump to form cosmic bodies of different sizes. __________ The gas particles are then condensed into liquid and solid states. __________ A star passed near the sun. 16  Earth and Life Science Grade 11/12 Unit 1: The Origin of the Universe and the Solar System Bibliography Chambers, John and Jacqueline Mitton. 2013. From Dust to Life: The Origin and Evolution of Our Solar System. New Jersey: Princeton University Press. Darling, David. 2016. Chamberlin-Moulton planetesimal hypothesis. Accessed March 16, 2017. http://www.daviddarling.info/encyclopedia/C/CMplanhypoth.html. Holder, Rodney D. and Mitton Simmon. 2013. Georges Lemaître: Life, Science and Legacy. Germany: Springer Science & Business Media. Schombert, James. 2012. Origin of the Solar System. University of Oregon. Accessed March 16, 2017. http://abyss.uoregon.edu/~js/ast121/lectures/lec23.html. Woolfson, Michael Mark. 2012. Time, Space, Stars and Man: The Story of the Big Bang. Singapore: World Scientific. 17