12 b) Describe how earthquakes and volcanoes transfer energy from Earth’s interior to the surface (e.g., seismic waves transfer mechanical energy, flowing magma transfers heat and mechanical energy). c) Model the factors that cause tectonic plates to move (e.g., gravity, density, convection). d) Model tectonic plate movement and compare the results of plate movement along convergent, divergent, and transform boundaries (e.g., mountain building, volcanoes, earthquakes, mid-ocean ridges, oceanic trenches). e) Design, build, and test a model that investigates local geologic processes (e.g., mudslides, earthquakes, flooding, erosion) and the possible effects on human- engineered structures (e.g., dams, homes, bridges, roads). Standard 3: Students will understand the atmospheric processes that support life and cause weather and climate. Objective 1: Relate how energy from the Sun drives atmospheric processes and how atmospheric currents transport matter and transfer energy. a) Compare and contrast the amount of energy coming from the Sun that is reflected, absorbed or scattered by the atmosphere, oceans, and land masses. b) Construct a model that demonstrates how the greenhouse effect contributes to atmospheric energy. c) Conduct an investigation on how the tilt of Earth’s axis causes variations in the intensity and duration of sunlight striking Earth. d) Explain how uneven heating of Earth’s atmosphere at the equator and polar regions combined with the Coriolis effect create an atmospheric circulation system including, Hadley cells, trade winds, and prevailing westerlies, that moves heat energy around Earth. e) Explain how the presence of ozone in the stratosphere is beneficial to life, while ozone in the troposphere is considered an air pollutant. Objective 2: Describe elements of weather and the factors that cause them to vary from day to day. a) Identify the elements of weather and the instruments used to measure them (e.g., temperature-thermometer; precipitation-rain gauge or Doppler radar; humidity-hygrometer; air pressure-barometer; wind-anemometer; cloud coverage-satellite imaging).
13 b) Describe conditions that give rise to severe weather phenomena (e.g., thunderstorms, tornados, hurricanes, El Niño/La Niña). c) Explain a difference between a low pressure system and a high pressure system, including the weather associated with them. d) Diagram and describe cold, warm, occluded, and stationary boundaries (weather fronts) between air masses. e) Design and conduct a weather investigation, use an appropriate display of the data, and interpret the observations and data. Objective 3: Examine the natural and human-caused processes that cause Earth’s climate to change over intervals of time ranging from decades to millennia. a) Explain differences between weather and climate and the methods used to investigate evidence for changes in climate (e.g., ice core sampling, tree rings, historical temperature measurements, changes in the extent of alpine glaciers, changes in the extent of Arctic sea ice). b) Explain how Earth’s climate has changed over time and describe the natural causes for these changes (e.g., Milankovitch cycles, solar fluctuations, plate tectonics). c) Describe how human activity influences the carbon cycle and may contribute to climate change. d) Explain the differences between air pollution and climate change and how these are related to society’s use of fossil fuels. 13. Investigate the current and potential consequences of climate change (e.g., ocean acidification, sea level rise, desertification, habitat loss) on ecosystems, including human communities. Standard 4: Students will understand the dynamics of the hydrosphere. Objective 1: Characterize the water cycle in terms of its reservoirs, water movement among reservoirs and how water has been recycled throughout time. a) Identify oceans, lakes, running water, frozen water, ground water, and atmospheric moisture as the reservoirs of Earth’s water cycle, and graph or chart the relative amounts of water in each. b) Describe how the processes of evaporation, condensation, precipitation, surface runoff, ground infiltration and transpiration contribute to the cycling of water through Earth’s reservoirs.
14 c) Model the natural purification of water as it moves through the water cycle and compare natural purification to processes used in local sewage treatment plants. Objective 2: Analyze the characteristics and importance of freshwater found on Earth’s surface and its effect on living systems. a) Investigate the properties of water: exists in all three states, dissolves many substances, exhibits adhesion and cohesion, density of solid vs. liquid water. b) Plan and conduct an experiment to investigate biotic and abiotic factors that affect freshwater ecosystems. c) Using data collected from local water systems, evaluate water quality and conclude how pollution can make water unavailable or unsuitable for life. d) Research and report how communities manage water resources (e.g., distribution, shortages, quality, flood control) to address social, economic, and environmental concerns. Objective 3: Analyze the physical, chemical, and biological dynamics of the oceans and the flow of energy through the oceans. a) Research how the oceans formed from outgassing by volcanoes and ice from comets. b) Investigate how salinity, temperature, and pressure at different depths and locations in oceans and lakes affect saltwater ecosystems. c) Design and conduct an experiment comparing chemical properties (e.g., chemical composition, percent salinity) and physical properties(e.g., density, freezing point depression) of freshwater samples to saltwater samples from different sources. d) Model energy flow in the physical dynamics of oceans (e.g., wave action, deep ocean tides circulation, surface currents, land and sea breezes, El Niño, upwellings). e) Evaluate the impact of human activities (e.g., sediment, pollution, overfishing) on ocean systems. Standard 5: Students will understand how Earth science interacts with society. Objective 1: Characterize Earth as a changing and complex system of interacting spheres.
15 a) Illustrate how energy flowing and matter cycling within Earth’s biosphere, geosphere, atmosphere, and hydrosphere give rise to processes that shape Earth. b) Explain how Earth’s systems are dynamic and continually react to natural and human caused changes. c) Explain how technological advances lead to increased human knowledge (e.g., satellite imaging, deep sea ocean probes, seismic sensors, weather radar systems) and ability to predict how changes affect Earth’s systems. d) Design and conduct an experiment that investigates how Earth’s biosphere, geosphere, atmosphere, or hydrosphere reacts to human-caused change. e) Research and report on how scientists study feedback loops to inform the public about Earth’s interacting systems. Objective 2: Describe how humans depend on Earth’s resources. a) Investigate how Earth’s resources (e.g., mineral resources, petroleum resources, alternative energy resources, water resources, soil and agricultural resources) are distributed across the state, the country, and the world. b) Research and report on how human populations depend on Earth resources for sustenance and how changing conditions over time have affected these resources (e.g., water pollution, air pollution, increases in population). c) Predict how resource development and use alters Earth systems (e.g., water reservoirs, alternative energy sources, wildlife preserves). d) Describe the role of scientists in providing data that informs the discussion of Earth resource use. e) Justify the claim that Earth science literacy can help the public make informed choices related to the extraction and use of natural resources. Objective 3: Indicate how natural hazards pose risks to humans. a) Identify and describe natural hazards that occur locally (e.g., wildfires, landslides, earthquakes, floods, drought) and globally (e.g., volcanoes, tsunamis, hurricanes). b) Evaluate and give examples of human activities that can contribute to the frequency and intensity of some natural hazards (e.g., construction that may increase erosion, human causes of wildfires, climate change).
16 c) Document how scientists use technology to continually improve estimates of when and where natural hazards occur. d) Investigate and report how social, economic, and environmental issues affect decisions about human-engineered structures (e.g., dams, homes, bridges, roads).
17 Universe
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18 How Do We Know What We Know About the Universe? Standard 1: Students will understand the scientific evidence that supports theories that explain how the universe and the solar system developed. They will compare Earth to other objects in the solar system. Standard 1, Objective 1: Describe both the big bang theory of universe formation and the nebular theory of solar system formation and evidence supporting them. Lesson Objectives • Investigate and report how science has changed the accepted ideas regarding the nature of the universe throughout history. • Describe the big bang theory and the evidence that supports this theory (e.g., cosmic background radiation, abundance of elements, distance/redshift relation for galaxies) The study of the universe is called cosmology. Cosmologists study the structure and changes in the present universe. The universe contains all of the star systems, galaxies, gas and dust, plus all the matter and energy that exist. The universe also includes all of space and time. Section 1: Evolution of Human Understanding of the Universe What did the ancient Greeks recognize as the universe? In their model, the universe contained Earth at the center, the Sun, the Moon, five planets, and a sphere to which all the stars were attached. This idea held for many centuries until new ideas and better observing instruments allowed people to recognize that Earth is not the center of the universe. Galileo’s telescope revealed four moons orbiting Jupiter (not Earth) and many more stars than are visible to the naked eye. More importantly, Galileo’s experiments established the principal of inertia which countered the physical arguments the Greeks used against a rotating and moving Earth. Terms to know o Big Bang Theory o Doppler Effect o Redshift o Universe
19 Timeline of cosmological theories 4th century BCE — Aristotle, building on the ideas of earlier astronomers, proposes that the Sun, Moon, planets, and stars revolve around a stationary Earth. This is known as the geocentric theory, meaning that the universe revolves around the earth. 2nd century AD — Ptolemy publishes a book that describes a mathematical procedure to calculate future positions of the Sun, Moon, and visible planets in the sky. It reaffirms that all these objects move around a stationary Earth. 1543 — Nicolaus Copernicus publishes his heliocentric (Sun-centered) theory that proposes that Earth is a planet in motion around the Sun. 1610 — Johannes Kepler analyzed the accurate astronomical observations of Tycho Brahe, and discovers that the planets move around the Sun in elliptical orbits.
20 1687 — Sir Isaac Newton publishes the laws of motion and gravity that are used to accurately predict the motion of the Moon and planets. 1915 — Albert Einstein publishes the General Theory of Relativity, proposing that mass and energy cause space and time to curve or warp. This can be used to describe large-scale motion throughout the universe. 1929 — Edwin Hubble discovers a velocity-distance relationship for galaxies that implies that the universe is expanding. In the early 20th century, an astronomer named Edwin Hubble (1889 – 1953) (see Figure 1 below) discovered that what was then called the Andromeda Nebula was so far away that it had to be a separate galaxy, outside our own Milky Way galaxy. Hubble realized that many of the objects that astronomers called nebulae were enormous collections of stars — what we now call galaxies. FIGURE 1 (a) Edwin Hubble used the 100-inch reflecting telescope at the Mount Wilson Observatory in California to show that some distant specks of light were galaxies. (b) Hubble’s namesake space telescope spotted this six galaxy group. Edwin Hubble demonstrated the existence of galaxies.
21 Hubble showed that the universe was much larger than our own galaxy. Today, we estimate that the universe contains several hundred billion galaxies—about the same number of galaxies as there are stars in the Milky Way Galaxy. Section 2: Is the Universe Getting Bigger or Smaller? After discovering that there are galaxies beyond the Milky Way, Edwin Hubble went on to measure the distance to hundreds of other galaxies. His data would eventually show how the universe is changing, and would even yield clues as to how the universe formed. Redshift. If you look at a star through a prism, you will see a spectrum, or a range of colors through the rainbow. The spectrum will have specific dark bands where elements in the star absorb light of certain wavelengths. By examining the arrangement of these dark absorption lines, astronomers can determine the composition of elements that make up a distant star. In fact, the element helium was first discovered in our Sun—not on Earth—by analyzing the absorption lines in the spectrum of the Sun. While studying the spectrum of light from distant galaxies, astronomers noticed something strange. The dark lines in the spectrum were in the patterns they expected, but they were shifted toward the red end of the spectrum, as shown in the Figure below. This shift of absorption bands toward the red end of the spectrum is known as redshift (- the shift of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects). This figure shows the absorption lines in the visible spectrum of a distant galaxy (right), as compared to absorption lines in the visible spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red, showing the galaxy moving away from the Earth.
22 Redshift occurs when the light source is moving away from the observer or when the space between the observer and the source is stretched. What does it mean that stars and galaxies are redshifted? When astronomers see redshift in the light from a galaxy, they know that the galaxy is moving away from Earth. On the other hand, a blueshifted galaxy is a galaxy moving towards the earth. If galaxies were moving randomly, would some be redshifted and others be blueshifted? Of course, since almost every galaxy in the universe has a redshift, almost every galaxy is moving away from Earth.
23 If a source of light is moving away from an observer then the electromagnetic spectrum will be redshifted, If the source is moving toward the observer it is blueshifted. Redshift can occur with other types of waves too. This phenomenon is called the Doppler Effect (an increase or decrease in the frequency of sound, light, or other waves as the source and observer move toward (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the redshift seen by astronomers). An analogy to redshift is the noise a siren makes as it passes you. You may have noticed that an ambulance seems to lower the pitch of its siren after it passes you. The sound waves shift towards a lower pitch when the ambulance speeds away from you. Though redshift involves light instead of sound, a similar principle operates in both situations. An animation of Doppler Effect: http://bit.ly/LxSbyM Youtube video: http://bit.ly/LiLRKL Edwin Hubble combined his measurements of the distances to galaxies with other astronomers’ measurements of redshift. From this data, he noticed a relationship, which is now called Hubble’s Law: the farther away a galaxy is, the faster it is moving away from us. What could this mean about the universe? It means that the universe is expanding. The Figure below shows a simplified diagram of the expansion of the universe. One way to picture this is to imagine a balloon covered with tiny dots to represent the galaxies. When you inflate the balloon, the dots slowly move away from each other because the rubber stretches in the space between them. If you were standing on one of the dots, you would see the other dots moving away from you. Also the dots farther away from you on the balloon would move away faster than dots nearby. Section 3: Expansion of the Universe Diagram An inflating balloon is only a rough analogy to the expanding universe for several reasons. One important reason is that the surface of a balloon has only two dimensions, while space has three dimensions. But
24 space itself is stretching out between galaxies like the rubber stretches when a balloon is inflated. This stretching of space, which increases the distance between galaxies, is what causes the expansion of the universe - (all existing matter and space considered as a whole; the cosmos). In this diagram of the expansion of the universe over time, the distance between galaxies gets bigger over time, although the size of each galaxy stays the same. An animation of an expanding universe is shown here: http://www.astro.ubc.ca/~scharein/a311/Sim/bang/BigBang.html One other difference between the universe and a balloon involves the actual size of the galaxies. On the balloon, the dots will become larger in size as you inflate it. In the universe, the galaxies stay the same size due to gravitational forces within the galaxy, just as the space between the galaxies expands. Section 4: Formation of the Universe Before Hubble, most astronomers thought that the universe didn’t change. But if the universe is expanding, what does that say about where it was in the past? If the universe is expanding, the next logical thought is that in the past it had to have been smaller. How Did the Universe Form? The Big Bang theory - (the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and
25 temperature) is the most widely accepted cosmological explanation of how the universe formed. If we start at the present and go back into the past, the universe is contracting – getting smaller and smaller. What is the end result of a contracting universe? According to the Big Bang theory, the universe began about 13 to 14 billion years ago. Everything that is now in the universe was squeezed into a very small volume. Imagine the entire known universe compressed into a single, hot, chaotic mass. An explosive expansion caused the universe to start growing rapidly. All the matter and energy in the universe, and even space itself, resulted from this expansion. What came before the Big Bang? There is no way for scientists to know since there is no remaining evidence. After the Big Bang In the first few moments after the Big Bang, the universe was unimaginably hot and dense. As the universe expanded, it became less dense and began to cool. After only a millionth of a second, protons (hydrogen nuclei) and neutrons could form. After a few minutes some of these subatomic particles came together to create helium nuclei. However it was not cool enough for electrons (which formed soon after protons and neutrons) to join with protons (hydrogen nuclei) or helium to make the first neutral atoms until about 380,000 years later. Matter in the early universe was smoothly distributed across space. However some of the hydrogen and helium were drawn together by gravity into clumps. These clumps were the seeds that eventually became countless trillions of stars, billions of galaxies, and other structures that now form most of the visible mass of the universe. These stars provide us with another piece of evidence that the universe is aging. The hydrogen in stars is being changed by fusion into helium and bigger elements. As time goes on the hydrogen continues to be used up and turned into helium. When the first elements formed after the Big Bang about 92% were hydrogen, with the rest being 8% helium and traces of lithium. Today we have about 74% hydrogen and 24% helium as well as the 90 other naturally occurring elements. By measuring how much hydrogen the universe started with, and the rate that stars use it, we can determine when stars began fusing. We can also use this rate to estimate how much longer fusion will continue. Right now you live in the middle of the universe’s life. Hundreds of billions of stars in hundreds of billions of galaxies are using up hydrogen and turning it into heavier elements as the universe continues to age.
