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EARTH AND SPACE SCIENCE WHAT YOU NEED TO KNOW Explain how evidence from stars and other celestial objects provide information about the processes that cause changes in the composition and scale of the physical universe. 1. 2. Describe that stars produce energy from nuclear reactions and that processes in stars have led to the formation of all elements beyond hydrogen and helium. Describe the current scientific evidence that supports the theory of the explosive expansion of the universe, the Big Bang, over 10 billion years ago. STARS AND ELEMENTS • Elements heavier than lithium are all synthesized in • • stars. During the late stages of a star’s life cycle, massive stars burn helium to carbon, oxygen, silicon, sulfur, and iron. Elements heavier than iron are produced in two ways: in the outer envelopes of super-giant stars and in the explosion of a supernovae. All these heavy elements are produced in stars through nuclear fusion. All carbonbased life on Earth is literally composed of stardust. Most of the material in our universe, however, is still hydrogen. Keep in mind that our Sun is a star and currently does, and will continue to do, these things. BIG BANG THEORY • The Big Bang Theory is the dominant scientific theory about the • • • • • origin of the universe. According to the Big Bang, the universe was created sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter and in all directions. There are three tests of the Big Bang theory (the expansion of the universe, the abundance of light elements, and cosmic microwave background radiation). These tests are supports for this theory. The universe is expanding because galaxies can be observed moving away from us at great speeds. There is a red shift in the light from these. Light elements, including H and He, make up the majority of elements in the universe. The Big Bang Theory received its strongest confirmation when the cosmic radiation was discovered in 1964 by Arno Penzias and Robert Wilson, who later won the Nobel Prize for this discovery. Although the Big Bang Theory is widely accepted, it probably will never be proved; consequentially, leaving a number of tough, unanswered questions. Most theories will never be proved! Explain that many processes occur in patterns within the Earth’s systems. 1. Explain the relationships of the oceans to the 2. 3. lithosphere and atmosphere (e.g., transfer of energy, ocean currents, and landforms). Summarize the relationship between the climatic zone and the resultant biomes. Explain climate and weather patterns associated with certain geographical locations and features (e.g., tornado alley, tropical hurricanes, and lake effect snow). EARTH AND CLIMATE Global circulations explain how air and storm systems travel over the Earth's surface. The global circulation would be simple if the Earth did not rotate, if the rotation was not tilted relative to the sun, and if Earth had no water. The sun heats the entire Earth, but where the sun is more directly overhead it heats the Earth and atmosphere more. The result is that the equator becomes very hot with the hot air rising into the upper atmosphere. That air would then move toward the poles where it would become very cold and sink, then return to the equator. One large area of high pressure would be at each of the poles with a large belt of low pressure around the equator. However, since the earth rotates, since the axis is tilted, and since there is more land mass in the northern hemisphere than in the southern hemisphere, the actual global pattern is much more complicated than this. EARTH AND CLIMATE Usually, fair and dry/hot weather is associated with high pressure, with rainy and stormy weather is associated with low pressure. You can see the results of these circulations on a globe. Look at the number of deserts located along the 30°N/S latitude around the world. Now, look at the region between 50°-60° N/S latitude. These areas, especially the west coast of continents, tend to have more precipitation due to more storms moving around the earth at these latitudes. CLIMATE AND BIOMES Biomes are defined as "the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment“. The importance of biomes cannot be overestimated. Biomes have changed and moved many times during the history of life on Earth. More recently, human activities have drastically altered these communities. Thus, conservation and preservation of biomes should be a major concern to all. The five biomes are aquatic, tundra, forests, deserts, and grasslands. Think about what it would be like to live in each! EARTH AND CLIMATE • Tornado alley: This is where warm, humid air from the Gulf of Mexico collides with cooler, drier air from Canada. These collisions create the huge thunderstorms that can form tornadoes. EARTH AND CLIMATE Tropical hurricanes: The terms "hurricane" and "typhoon" are other names for a strong "tropical cyclone". Five factors are necessary to possibly form tropical cyclones: • Warm waters (or, more specifically, the moisture in the air above them) are the energy source for tropical cyclones. When these storms move over land or cooler areas of water, they weaken rapidly. • Upper level conditions must be conducive to thunderstorm formation. • A pre-existing weather disturbance. This is most frequently provided by tropical waves—non-rotating areas of thunderstorms that move through the world's tropical oceans. • A distance of approximately 10 degrees or more from the equator, so that the Coriolis effect is strong enough to initiate the cyclone's rotation. • Lack of vertical wind shear (change in wind velocity or direction over height). High levels of wind shear can break apart the vertical structure of a tropical cyclone. EARTH AND CLIMATE • Lake effect snow: Lake-generated snow squalls form when cold air, passing for long distances over the relatively warm waters of a large lake, picks up moisture and heat and is then forced to drop the moisture in the form of snow upon reaching the downwind shore. Lakeeffect snows are common over the Great Lakes region because these large bodies of water can hold their summer heat well into the winter, rarely freeze over, and provide the long distance which allows the air to gain the heat and moisture required to fuel the snow squalls. Lake-effect snows are most pronounced and effective wherever terrain features such as small hills or mountains are oriented along the lee shores. This is what it would be like in Cleveland! EARTH AND CLIMATE Moisture for storms comes from large bodies of water, primarily oceans, and are pushed over the continents by air currents. When this moist air comes over a land and hits a mountain, it is forced up the range where it cools, condenses, and often falls as rain. Mountains often receive much more precipitation than the areas around them. As this air pushes over the top of the mountain and down the other side, it can again expand, although it has now lost much of its moisture. This "Rain Shadow" effect can be so strong that the area behind a mountain is a desert. In fact, all the deserts of North America are influenced by this "Rain Shadow" effect. Explain the 4.5 billion-year-history of Earth and the 4 billion-year-history of life on Earth based on observable scientific evidence in the geologic record. 1. Explain that gravitational forces govern the characteristics and movement patterns of the planets, comets, and asteroids in the solar system. 2. Explain how geologic time can be estimated by multiple methods (e.g., rock sequences, fossil correlation and radiometric dating). 3. Describe how organisms on Earth contributed to the dramatic change in oxygen content of Earth’s early atmosphere. SOLAR SYSTEM • How does gravity work? There are two ideas you need to know. These ideas work throughout the universe. The more massive an object is, the more gravity it has. The closer two objects are, the stronger the gravitational pull between them. SO, putting these two rules together, the more massive and the closer two objects are, the greater the gravitational attraction between them. Think of Newton when you think of gravity! Think of how early scientists got in trouble for thinking the Sun, rather than the Earth, was the center of our solar system! Asteroids are rocky lumps of material, sometimes known as minor planets and exist mostly between Mars and Jupiter. Comets are a bit like giant dirty ice-balls with diameters between five and fifty kilometers. They, like the planets, are kept in orbit by the force of gravity. GEOLOGIC TIME • Fossil correlation – Fossils can often be used to estimate dates of rocks in which they are embedded. They can also be used to make guesses about what earlier times were like (climate, etc). • Radiometric dating – Rocks often contain radioactive materials that are decaying at a constant rate. Looking at the fractions of these materials now present helps us date things. Carbon dating is a good example. Describe the finite nature of Earth’s resources and those human activities that can conserve or delete Earth’s resources. • Use of resources • Urban growth and waste disposal • Farming (C and N cycles, erosion, crop rotation, fertilizers) • Pest control • Global warming • Exponential population growth Explain the processes that move and shape Earth’s surface. • • • Explain how the slow movement of material within Earth results from: a. thermal energy transfer (conduction and convection) from the deep interior; b. the action of gravitational forces on regions of different density. Explain the results of plate tectonic activity (e.g., magma generation, igneous intrusion, metamorphism, volcanic action, earthquakes, faulting, and folding). Explain sea-floor spreading and continental drift using scientific evidence (e.g., fossil distributions, magnetic reversals, and radiometric dating). CONTINENTAL DRIFT Wegener was intrigued (like people before him) by plant and animal fossils found on the matching coastlines of South America and Africa, now widely separated by the Atlantic Ocean. He reasoned that it was impossible for most of these organisms to have swum or have been transported across the ocean. To him, the presence of identical fossil species along the coastal parts of Africa and South America was the best evidence that the two continents were once joined. His theory was also supported by the discovery of both fossils of tropical plants and dinosaurs in Antarctica that led him to the conclusion that this now frozen land once must have been situated closer to the equator where lush, swampy vegetation could grow. His downfall: HOW? WHAT FORCES? EARTH’S STRUCTURE In the picture, you can see the thin crust, over the mantle and then the core. Most of the mantle and core are liquid and can flow. PLATE TECTONICS What causes these plates to move? Since plates move, do they run into each other? The Earth’s crust is made up of a dozen or so major plates and several minor plates. These tectonic plates are constantly on the move. The fastest plate races along at 15 centimeters (6 inches) per year while the slowest plates crawl at less than 2.5 centimeters (1 inch) per year. You'll notice that most plates are part continental and part oceanic. Continental plates tend to be made of lighter, less dense rocks and oceanic plates are made of heavier, more dense rocks. CONVERGENT BOUNDARIES In a contest between a dense oceanic plate and a less dense continental plate, it’s the dense oceanic plate that sinks. In this case, one plate is pulled beneath another (subduction), forming a deep trench. The long, narrow zone where the two plates meet is called a subduction zone. Look for curved volcanic mountain ranges with deep trenches alongside. Boundaries like this are known to produce historic earthquakes of great magnitudes. When two oceanic plates collide, the plate that is older, therefore colder and denser, is the one that will sink. MORE ON CONVERGENT BOUNDARIES • The Himalayan mountain • range provides a spectacular example of continent vs. continent collision. When two continental plates meet headon, sometimes neither one can sink because both plates are too buoyant. It is here that the highest mountains in the world grow. At these boundaries solid rock is crumpled and faulted. Huge slivers of rock, many kilometers wide are thrust on top of one another, forming a towering mountain range. Look at how older rocks that are colder and denser may now be layers under younger rocks! DIVERGENT BOUNDARIES If plates collide, can they also separate? An example of divergent plate boundaries is in East Africa where a spreading process has already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. A new spreading center may be developing under Africa along the East African Rift Zone. Geologists believe that, if spreading continues, the three plates that meet at the edge of the present-day African continent will separate completely, allowing the Indian Ocean to flood the area and making the easternmost corner of Africa (the Horn of Africa) a large island. TRANSFORM PLATE BOUNDARIES At transform plate boundaries plates grind past each other side by side. Unlike convergent or divergent boundaries, the plates do not go under or over each other. A good example of this type of boundary is the one that separates the North American plate from the Pacific plate along the San Andreas fault, a famous transform plate boundary that’s responsible for many of California’s earthquakes. The San Andreas fault is unusual because most transform boundaries occur on the ocean floor. Movement along the San Andreas (or any other fault) can occur either in sudden jolts or in a slow, steady motion called creep. Which is a bigger problem for us here on Earth? CARTOON ACTIVITY • Take your cartoon and place it in line with the others so that the pictures tell a story. This is very similar to how we take fossil pieces and put them together to tell a story about the past.