Elementary Earth and Space Science Methods by Ted Neal is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
1
Introduction
Dear Future Science Teachers,
We created this book to help you as both a college student and a future teacher. Dr. Ted Neal asked us to help him create this resource from the perspective of students who have taken Science Methods II–what would we want in a textbook for this course? With this in mind, we have gathered and created resources to help you better understand science and feel confident in your abilities as a future teacher.
This book is divided into four parts which align with the Science Methods II course: Space Science, Earth Science, Climate Change, and Pedagogy. Within each part, the material is broken down into smaller chapters. Here you will find written explanations, video links, glossary terms, key takeaways, and practice quizzes to help you understand the material. This book is designed to be a flexible resource; use it as much or as little as you need throughout the course.
As Ted likes to say, science is everywhere and it is everything. We hope this book can help you on your journey as a learner and teacher of science.
Cheers,
Rachel Dunn, Jenny Haley, Ella McDonald, Ben Smith
I
Welcome to Space Science. This part is divided into four chapters:
Additionally, there is a practice quiz at the end that covers the entire unit.
1
Heliocentrism vs Geocentrism
In early times, humans believed in geocentrism–the theory that Earth is at the center of the solar system, and the Sun and other planets revolve around it. During the Renaissance in the 1500s, Copernicus popularized the concept of heliocentrism–the theory that the Sun is at the center of the universe and Earth orbits the Sun.
Throughout Copernicus’ lifetime, the scientific community widely denied the theory of heliocentrism. A generation later, the Sun-centered theory became more commonly accepted when Galileo invented the telescope in 1609, making it easier to observe space. Additionally, Galileo made a variety of discoveries about our solar system that disproved the geocentric model of the universe. Despite these new discoveries, however, there was still significant pushback against heliocentrism, particularly from the Catholic Church.
At the time, the Church defended its stance on geocentrism because it believed Galileo’s discoveries left too many questions unanswered and did not explicitly prove heliocentrism. During this period, a case could still technically be made for geocentrism until technology advanced enough for scientists to discover more evidence supporting heliocentrism.
Additionally, the Church had certain clergy who interpreted parts of the Bible very literally, as if it were a science textbook rather than a theological work. Galileo’s claims were scandalous in their eyes because heliocentrism directly conflicted with certain biblical passages. For these reasons, the Church put Galileo on trial, convicted him of heresy, and sentenced him to house arrest for the remainder of his life. In 1822, the Church eventually accepted the theory of heliocentrism once there was enough scientific evidence to claim it as truth.
Key Takeaway
To remember the theories of heliocentrism and geocentrism, break down the names and look at the etymology.
Equinox & Solstice
There are 2 equinoxes and 2 solstices per year – Spring Equinox, Autumn Equinox, Winter Solstice, and Summer Solstice. Equinoxes (which sounds like the word equal) mark the day in which all of Earth receives an equal amount of sunlight–12 hours. This equal amount of sunlight occurs when the Equator is directly in line with the Sun. The Spring Equinox happens around March 20th and the Autumn Equinox happens around September 23rd each year.
Solstices mark the days of the year in which a hemisphere receives the least amount of sunlight (aka the shortest day of the year) and the most amount of sunlight (aka the longest day of the year). These days occur when one of the tropic lines are directly in line with the Sun. In the Northern Hemisphere, the Winter Solstice (the day with the least sunlight, usually around December 21) occurs when the Tropic of Capricorn (the southern tropic line) is in line with the Sun. The Summer Solstice (the day with the most sunlight, usually around June 21) occurs when the Tropic of Cancer (the northern tropic line) is in line with the Sun.
Eclipses
Eclipses happen when light is blocked. There are two types of eclipse that we can see on Earth: solar eclipses and lunar eclipses.
To understand each type of eclipse, you must determine whether the Sun or Moon is being blocked.
For more explanation of lunar eclipses, watch the video below.
Seasons
Earth orbits in the same plane as the other planets in our solar system: the Plane of the Ecliptic. However, Earth’s is also tilted on it axis. This tilt never changes in relation to space, so different areas of Earth are tilted toward the Sun at different times of year. This is why we have seasons.
Additionally, the Northern and Southern Hemispheres have opposite seasons due to the tilt of Earth’s axis. When the Northern Hemisphere is tilted towards the Sun it is summer (this is winter in the Southern Hemisphere). When the Southern Hemisphere is tilted towards the Sun it is summer (this is winter in the Northern Hemisphere).
Earth’s seasons are explained in the image below.
Key Takeaways
2
Phases of the Moon
The Moon orbits around Earth once every 28 days, or about once a month. Depending on where the Moon is in its orbit, it appears different from Earth. However, everyone on Earth sees the same phase of the Moon on the same day.
The phases of the moon are:
For the first half of this cycle, the visible part of the Moon waxes or grows larger. After reaching a full moon, the Moon wanes or grows smaller for the second of the cycle.
The image, below, shows the Moon’s phases.
For further explanation of the Moon’s phases, watch the following video.
Characteristics of the Moon
Sides of the Moon
There are two sides of the moon: the near side (the side we can see from Earth) and the far side (also known as the dark side). The Moon does not create its own light; it gets light from the Sun. As such, the dark side is not actually dark–it is just called the dark side because we cannot see it from Earth.
Since Earth has a larger mass, it exerts a stronger gravitational pull on the Moon. Earth’s pull controls the Moon’s orbit so that the Moon rotates once on its axis in the same amount of time it takes to orbit Earth. Therefore, the same side of the Moon is always facing Earth and we have a near side and a dark side. This effect is called tidal locking.
Click this link to see animation of how tidal locking works as the Moon orbits Earth.
Near side of the Moon | Far side of the Moon |
|
|
|
|
|
|
Sputnik and the Space Race
On October 4th, 1957 the Soviet Union successfully launched Sputnik, the world’s first artificial satellite, into Earth’s orbit. This successful launch of Sputnik sparked the Space Race between the Soviet Union and the United States. These two countries competed to get the first human to land on the Moon.
On January 31, 1958, the United States launched Explorer 1, a satellite that discovered the magnetic radiation belts around Earth. That same year, the United States created the National Aeronautics and Space Administration (NASA). In 1959, the Soviet Union launched Luna 2, the first spacecraft to land on the Moon. In April 1961, the Soviet astronaut Yuri Gagarin became the first person in space when he orbited Earth. Shortly after, astronaut Alan Shepard became the first American in space in May 1961.
The Space Race heated up and President John F. Kennedy claimed that the United States would put a man on the Moon before the end of the decade. In 1962, American astronaut John Glenn successfully orbited the Earth. In 1968, American mission Apollo 8 orbited the Moon. Finally, in 1969, the American mission Apollo 11 successfully landed the first two people on the Moon: astronauts Neil Armstrong and Buzz Aldrin.
Interesting Fact
Dr. James Van Allen from the University of Iowa created the radiation detector that launched on the Explorer 1 satellite. This led to the discovery of magnetic radiation belts around Earth which are known as Van Allen radiation belts in his honor. Van Allen Hall on Iowa’s campus is also named after him.
Women and Space
Traditionally, the story of the Space Race features male scientists and astronauts. However, women have played a key role in the history of American space exploration. NASA mathematicians Katherine Johnson and Dorothy Vaughan along with engineer Mary Jackson were key members of the team that launched John Glenn into space in 1962. In addition to this mission, these women had long careers at NASA. Their stories have recently been popularized in the movie Hidden Figures.
Initially, women were seen to have a physical advantage as astronauts; they tend to be lighter, shorter, and consumer less food. In 1960, astronaut Jerrie Cobb had logged twice as many flying hours as John Glenn. But NASA made a requirement that astronauts had to be military pilots, a job only men could have. A group of 13 female astronauts, including Cobb, was gathered and subjected to the same tests as the male astronauts. The women passed all of the tests, and in many cases, performed better than the men. Still, NASA refused to support the female astronauts. In 1983, Sally Ride became the first female astronaut in space.
3
The Milky Way
A galaxy is a collection of billions of stars, gas, and dust held together by gravity in space. Our solar system is located in the Milky Way Galaxy. The Milky Way is a large spiral galaxy; it got its name because it appears as a milky band of light in the sky. There are hundreds of billions of stars in our galaxy. Our Sun, Earth, and all the planets are located halfway between the center and the outer edge on a small partial arm called the Orion Spur. At the center of the Milky Way is a supermassive black hole named Sagittarius A which has a mass of 4 million suns.
Planets
There are 8 planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. To remember the order of the planets (closest to farthest from the sun), use the acronym “My Very Educated Mother Just Served Us Nutella.”
The four inner planets–Mercury, Venus, Earth, and Mars–are rocky planets because they have a solid surface. The four outer planets–Jupiter, Saturn, Uranus, and Neptune–are gaseous planets because they are composed of gases, mainly hydrogen and helium. Notice that the rocky planets are much smaller in size and the gaseous planets are larger. One theory for this is that when the Sun turned on and became a star, it caused the gas clouds of the four inner planets to blow away. The rocky planets were left with a smaller, solid planet. The gaseous planets are farther from the sun, so they retained their composition. As they increased in mass, their gravity increased which allowed them to attract more and more material from space and grow larger in size.
Sizes and Distances of Planets
The image below shows the huge variance in size between planets in our solar system. Notice the differences in size between the inner, rocky planets and the outer, gaseous planets.
Measurements of Our Solar System
Element | Diameter (km) | Distance from the Sun (x106) (km) |
Sun | 1,392,000 | ————————– |
Mercury | 4,897 | 57.9 |
Venus | 12,104 | 108.2 |
Earth | 12,756 | 149.6 |
Mars | 6,794 | 227.9 |
Jupiter | 142,980 | 778.6 |
Saturn | 120,540 | 1433.5 |
Uranus | 51,120 | 2872.5 |
Neptune | 49,530 | 4495.1 |
Why is Pluto Not a Planet?
Pluto was the ninth planet in our solar system until a controversial 2006 decision when it was reclassified as a dwarf planet. Pluto meets two requirements to be a planet: it orbits around the sun and its gravity formed the planet into a round shape. However, it does not meet the third requirement of “clearing the neighborhood.” Planets must have gravitational dominance and clear the neighborhood around their orbit; this means that large planets (more mass=more gravity) either attract or eject other, smaller bodies from that region of space. Several other dwarf planets and similarly-sized space objects were discovered in the solar system near Pluto’s orbit in the Kuiper Belt. Therefore, Pluto has not cleared the neighborhood and so it cannot be considered a planet.
Asteroids
During the early life of our solar system, dust and rocks in space were pulled together by gravity to form the planets. Not all the dust and rocks were made into planets; smaller, rocky remnants called asteroids remain and orbit the Sun in our solar system. Between Mars and Jupiter, you can find the Main Asteroid Belt which is where most of the known asteroids orbit.
Other Objects in the Solar System
4
The Big Bang
The Big Bang is the best-supported scientific theory for how the universe was created. 13.7 billion years ago there was nothing and nowhere. Everything that ever existed was contained in a subatomic particle that was billions of times smaller than an atom. Within a fraction of a second, this amazingly tiny particle stretched and inflated to an unimaginably huge size. Space, time, and the fundamental particles of the universe were created in this instant.
Key Takeaway
Although the word “bang” is part of the name, the Big Bang was an expansion or an inflation rather than an explosion.
Although there are alternate theories, the Big Bang theory is supported by multiple sources of scientific evidence.
For more explanation of the Big Bang theory, watch the following video.
The Life Cycle of Stars
All stars begin their lives as clouds of gas and dust which are called nebulae. The particles in a nebula start to attract, so their combined mass increases. Therefore, they have more gravity which pulls in even more particles. Eventually, there will be enough particles under intense heat and pressure in the center core and nuclear fusion can occur. The star ignites and becomes a fully functioning star.
The image, below, shows the life cycles of different types of stars.
Depending on the amount of material in the nebula, an average star (like the Sun) or a supermassive star is formed. As the star burns through its fuel, it loses mass; therefore, it has less gravity and its size increases. An average star turns into a red giant. As it continues burning fuel, the red giant becomes very large. Then, the outer layers are blown off creating a planetary nebula and the inner core of the star remains, called a white dwarf star.
A supermassive star turns into a super red giant. These stars have more mass so they burn through their fuel more quickly, therefore losing gravity and becoming extremely large. Eventually, the super red giant will run out of fuel, collapse in on itself, and create a giant explosion called a supernova. From there, the star can either form a black hole or an extremely compact neutron star.
Interesting Fact: We Are Made of Stardust
Galaxies
A galaxy is a collection of billions of stars, gas, and dust held together by gravity in space. Using the Hubble Space Telescope, scientists can take images of space. In one small area, called the eXtreme Deep Field or XDF (image below) each of the bright spots is an entire galaxy–there are 5,550 galaxies within the image.
For comparison, the area in the image is much smaller than the size of our Moon (image below). There are probably 100 hundred billion galaxies in the entire universe.
As seen in the image, below, there are 3 shapes of galaxies: spiral, elliptical, and irregular. Our galaxy, the Milky Way, is a spiral galaxy. Most galaxies have a supermassive black hole at the center which has an extremely strong gravitational pull that holds the entire galaxy together.
Black Holes
A black hole is an area in space with extremely strong gravity from which no light can escape. Thus, the area appears black. At the end of its lifecycle, a supermassive star collapses in on itself which causes a huge explosion called a supernova; this results in the formation of a black hole.
Seen below, scientists captured the first image of a black hole in 2019 using powerful telescopes. Since black holes trap all light inside, the dark spot in the center of the image is the black hole’s shadow surrounded by a ring of glowing gas in space. Based on this image, scientists were able to determine that the this black hole’s mass is 6.5 billion times larger than the mass of our Sun.
For more explanation of black holes, watch the following video.
Origins of the Sun, Earth, and Moon
Our solar system was most likely formed from a giant rotating nebula after a former star underwent a supernova. 4.65 billion years ago, this rotation and intense gravity caused the nebula to collapse on itself. This caused it to spin faster and flatten into a disk shape, the Plane of the Ecliptic. Much of this material was pulled toward the center of the disk and a star was formed: the Sun. The Sun contains 99.8% of the mass in our solar system.
Although it is enormous compared to the size of Earth, the Sun is an average-sized star. It is mostly made of hydrogen and helium. Currently, it is halfway through its fuel supply. In around 5-6 billion years, the Sun will burn all of its fuel and become a white dwarf star.
After the Plane of the Ecliptic was formed, the planets formed from the leftover gas and dust orbiting around the Sun. One theory says that when the Sun turned on and became a star, the force of its energy blew off the gas clouds around the four inner planets which is why they are rocky and the outer planets are gaseous. Earth, a rocky planet, is about 4.65 billion years old. Scientists believe that life on Earth appeared approximately 3.5 billion years ago, based on evidence found in fossils.
Key Takeaway
Earth was NOT formed during the Big Bang.
The Moon was formed when a Mars-sized object named Theia collided with the Earth. Early in its creation, Earth was molten. When it collided with Theia, chunks of Earth’s crust were ejected into space. Gravity bounded these pieces together and the Moon was formed, eventually cooling and hardening into its current rocky state. Evidence which supports this theory include that the Moon and Earth have very similar composition including an iron core, mantle, and crust, although the Moon is less dense since it was formed from lighter elements in Earth’s crust. The Moon is held to Earth by gravity and it is Earth’s only natural satellite object, although the distance between them is increasing by about 1.6 inches per year.
5
Follow this link to take the space science practice quiz. You will get immediate feedback on your answers.
II
Welcome to Earth Science. This part is divided into three chapters:
Chapters one and two will be covered on the midterm exam. Chapter three will be covered on the final exam. Additionally, there are two practice quizzes at the end.
6
Geologic Time
Earth was formed about 4.65 billion years ago. Scientists use the geologic time scale to describe events that have happened throughout Earth’s history.
If the entirety of Earth’s history was represented on a clock, humans would appear at 11:59:40 PM.
Origins of Life on Earth: Bacteria, Plants, and Animals
Snowball Earth
At least three times in Earth’s history, the planet was engulfed almost entirely in ice–an event called Snowball Earth. These events happened between 580 and 750 million years ago. Evidence for Snowball Earth comes from sedimentary rocks. In a normal ice age, the types of rock deposited by glaciers would be found mostly near Earth’s poles. However, geologists found glacial rocks of similar ages around the world, at both the poles and equatorial regions. This led to the Snowball Earth theory.
Snowball Earth was caused by a chain of events called a positive feedback loop. Ice has a high albedo and is very insulating, so it is not heated up efficiently by sunlight. As ice accumulated on the planet, it increasingly reflected more sunlight and cooled Earth even further. Thus, this created a cycle of ice formation, increased albedo, and cooling of Earth which continued until the entire planet was covered in ice.
Why is Earth not covered in ice now if the positive feedback loop continues forever? The leading theory is that volcanoes continued erupting during Snowball Earth, emitting high levels of carbon dioxide, which was trapped under the ice. Eventually, the carbon dioxide built up enough to start melting the ice. Ice turned to water, which has a lower albedo and thus absorbed more of the Sun’s energy. This led to a new positive feedback loop that resulted in warming of the planet and the end of Snowball Earth. Additionally, it is believed that bacterial life on Earth survived the harsh conditions during Snowball Earth events by living near the heat sources from volcanoes.
Pangaea
Due to plate tectonics, Earth’s land is constantly shifting and changing over time. 250 million years ago, all of Earth’s landmass was united in a single supercontinent called Pangaea. About 200 million years ago, this supercontinent began to break up into pieces as the plates moved away from each other. Smaller landmasses were formed until, eventually, the continents we recognize today were shaped. It is easy to see how certain continents, like South America and Africa, once fit together. Even today, the location of the continents continues to fluctuate. Scientists theorize that a new supercontinent, called Pangaea Proxima, could form 250 million years in the future.
Continental Drift
Proposed by scientist Alfred Wegener, the theory of continental drift was one of the earliest ways to explain why continents moved over time. Wegener noticed that the shape of Earth’s continents, such as South America and Africa, could fit together like a jigsaw puzzle. He also studied fossils from different continents that showed the remains of identical plants and animals spread throughout the world. For example, dinosaurs lived during the Triassic, Jurassic, and Cretaceous periods. As Pangaea broke into different pieces, fossils show that dinosaurs spread to different continents and evolved into different species over time. Based on this evidence, Wegener theorized that all of Earth’s continents were originally united in the supercontinent Pangaea. Over time, they drifted apart to their current positions.
While parts of this theory were correct, Wegener’s ideas had some flaws. For example, Wegener was unable to explain how the continents had separated over time. Consequently, this theory was replaced by the plate tectonics theory which is discussed in the next chapter, “Earth’s Structure: At the Surface and Underground”.
Key Takeaways
Timeline of Earth’s History:
**Change so dinosaurs come before humans, I put the stuff about plants and animals in a purple box above…so then this timeline can kind of be the summary from the whole chapter.
7
Layers of Earth
Earth is made up of four layers. The outermost layer is called the crust. The crust is made up rocks such as basalt and granite and it is very thin in comparison to the other layers. The crust is broken into many pieces called plates. There are two types of plates: continental plates and oceanic plates. Continental plates are much thicker than oceanic plates. Picture the depth of the ocean floor compared to the land; the ocean floor is much far below the land and, therefore, oceanic plates are thinner than continental plates.
The next layer is the mantle which is between the crust and core. This is the largest and thickest layer of Earth. The upper part of the mantle is made of magma; the tectonic plates float on this layer which is how they move.
Finally, Earth’s core is made of two layers: the outer and inner core. The liquid outer core is mostly made of iron and nickel. It is incredibly hot, so the metals remain in a liquid state. The flow of the liquid metals creates Earth’s magnetic field which is why compasses always point north. Additionally, the magnetic field protects the planet from extreme weather and radiation in space. The solid inner core is also made of iron and nickel. However, this layer is solid because the materials are under intense pressure at the center of Earth. Scientists know that the inner core is solid because of how seismic waves from earthquakes travel through the interior of Earth. The waves are unable to travel straight through the layers; instead they are refracted or bent by the dense inner core, so scientists believe this layer is solid.
Plate Tectonics
Plate tectonics explains how Earth’s plates move. Earth’s crust is divided into many plates which float on the molten upper layer of the mantle. This area is called the lithosphere. The movement of the plates is driven by convection currents in the mantle. Heat rises from the mantle and cools as it gets closer to the surface; from there, it sinks down where it is reheated and the cycle repeats. This creates a current that moves the plates. Although they are constantly moving, each plate moves very slowly–about 3 to 5 centimeters (1 to 2 inches) per year.
Tectonic Plate Boundaries
There are three types of tectonic plate boundaries:
Depending on the type of tectonic plate and the type of plate boundary, different landforms can occur along plate boundaries.
As seen in the map below, the Ring of Fire is an area in the Pacific Ocean bounded by several tectonic plates. Most of Earth’s earthquakes and volcanoes occur in this area due to the shifting of tectonic plates along these boundaries.
Volcanoes
A volcano is a vent that allows magma, rock fragments, ash, and gases to escape to the surface of a planet or moon. Volcanoes have created more than 80% of Earth’s surface. Volcanoes are found on every continent and on the sea floor in Earth’s oceans, as well as on several planets and moons in space.
When the material (magma, ash, and gases) from a volcano comes to Earth’s surface, it is called an eruption. There are two different types of volcanic eruptions: explosive and effusive. Explosive eruptions are when the magma is fiercely fragmented and rapidly expelled from a volcano. Effusive eruptions are when lava steadily flows out a volcano onto the ground.
How Volcanoes are Formed
Volcanoes form when magma from deep within Earth rises to the surface. Volcanoes can be formed in 3 ways: converging tectonic plates, diverging tectonic plates, or over a hot spot.
When an oceanic plate converges with a continental plate, the oceanic plate subducts under the continental plate forming a subduction zone. At this zone, the denser plate is pushed under the other and the rock melts under intense heat and pressure as it is pushed further into Earth. Thus, the melted rock turns to magma and is able to rise to Earth’s surface as a volcano.
When two plates diverge, magma rises up to fill the space in between and an underwater volcano forms.
A hot spot is an extremely hot area in the mantle where magma can rise up to the surface and create volcanic activity. The heat comes from deep within Earth, melting rock at the crust and forming magma. More typically, volcanoes occur along plate boundaries, but hot spots are located in the middle of tectonic plates. Yellowstone National Park in Wyoming is a supervolcano located over a hot spot. It hasn’t erupted for 174,000 years and is not expected to erupt soon. However, features in the park such as the geyser Old Faithful are fueled by volcanic activity over the hot spot.
The Hawaiian Islands, an island arc, were also formed by hot spot volcanoes on the Pacific Plate. The Pacific Plate is slowly moving northwest over time while the hot spot stays in the same place. As such, different areas of the plate are located over the hot spot at different times. Material from underwater volcanic eruptions at the hot spot builds up until it eventually reaches the surface, forming an island.
Based on the ages of rocks found on the islands, scientists can determine that the westernmost island, Kauai, is the oldest. 5 million years ago, Kauai was located over the hot spot. As the Pacific Plate shifted west, new islands in the chain were formed. Therefore, the easternmost island, the Big Island, is the youngest island and it is currently located over the hot spot. Eventually, new islands will continue to form in Hawaii. Scientists have detected a the beginnings of a new island, named Loihi, located southwest of the Big Island. Although it is currently located far below the ocean surface, volcanic eruptions have started to form Loihi and it will reach the surface in tens of thousands of years.
Earthquakes
Tectonic plates float on the mantle, the layer below the crust. Breaks in the rock of the plates are called faults; these can occur in the form of plate boundaries as well as smaller cracks on the interior of plates. The rock moves along these fault lines at transform boundaries. Sometimes, however, they are unable to easily pass. The plates continue to push into or slide past each other which causes intense stress to build up. Eventually, the rocks will snap and the pressure will be released in the form of powerful seismic waves. This causes the ground to shake–an earthquake.
Law of Superposition
The Law of Superposition states that deeper layers of rock are older; deeper layers of rock were formed before layers that are closer to the surface. The Law of Original Horizontality states that successive layers of rock are formed in flat, horizontal layers; this is because gravity pulls down on the rock when it forms. Using these laws, geologists and archaeologists can determine the relative age the layers of rocks.
Sometimes, however, layers of rock do not match up horizontally. Due to the movement of Earth’s plates, the layers constantly shift and may become skewed or tilted. Additionally, surface level factors such as erosion and weathering can affect the top layer of earth by washing parts of it away. Finally, intrusions of magma (which forms igneous rock) can disrupt the horizontal layers beneath the surface. All of these factors provide clues for scientists to understand what occurred and when it happened at different times on Earth.
In the image, above, the layers of rock oldest to youngest are C, B, A, D.
To learn more about the Law of Superposition, the following video is highly-recommended viewing:
Fossils
Fossils are the remains of plants or animals that have been preserved in rock. Fossils form when the remains of a plant or animal are quickly buried after they die. Over time, the remains are replaced by minerals and compacted between layers of sediment to form fossils in sedimentary rock. Fossils are very fragile so they can only be found in sedimentary rocks; the extreme heat and pressure needed to form igneous and metamorphic rocks would destroy the fossil.
Fossils can also tell a story. Using the Laws of Superposition and Original Horizontality, geologists can figure out the relative age of a certain layer of rock. Sometimes, a specific type of fossil is found widely throughout one of these horizontal layers. Scientists can infer, then, that the organism lived during the same geologic time; this is called an index fossil. If the same type of fossil is found in other areas of rock, scientists can figure out that certain layers of rock were formed at the same time as well. In this way, fossils are a record of geologic time that tell a story to the people who find them.
Disciplinary Core Ideas
ESS1.C: The History of Planet Earth
8
Follow this link to take the earth science midterm quiz. The information on this quiz will be on the midterm exam. You will get immediate feedback on your answers.
9
Types of Rocks
Rocks are classified as three types: Igneous, Sedimentary, and Metamorphic.
Igneous | Sedimentary | Metamorphic |
|
|
|
|
|
|
Intrusive Igneous Rocks | Extrusive Igneous Rocks |
When magma cools underground, it cools more slowly. Since it is inside Earth, it is well protected and forms larger crystals. This is called an intrusive rock. | When magma cools in water or on the surface of Earth, like after a volcano erupts, it cools more quickly and forms smaller crystals. This is called an extrusive rock. |
Rock Cycle
The key processes in the rock cycle are heat & pressure and weathering & erosion. Each type of rock can undergo different changes that affect its form and the type of rock it is.
Igneous rocks:
Sedimentary rocks:
Metamorphic rocks:
Geodes
A geode forms when a cavity forms in a rock, which can occur in different ways. One way a cavity can form occurs when a bubble of carbon dioxide and water vapor forms in flowing lava. As the molten rock cools and the gas dissolves, an empty space is left behind. Another possibility in which a cavity can form occurs when lava solidifies under water. Sometimes the outside of the melted rock cools before the inside, which becomes brittle and breaks a little bit due to the weight of the liquid inside. That liquid then leaks out, leaving a hollow space and a crack for minerals to seep into overtime. Cavities that allow geodes to form are most commonly found in igneous rock formed by cooling lava or magma.
However, cavities can also form in sedimentary rocks, such as limestone and sandstone. In these particular rocks, the cavity generally forms a solid core. In some cases, in the sediment, a mass of minerals begin to dissolve and leave behind space. In other cases, organic material, like a piece of wood, gets buried in the sediment and eventually weathers over time, leaving behind empty space. Once these rocks are hollow, or at least semi-hollow, various minerals are able to seep in through the rock’s microscopic pores, creating crystalline structures over long periods of time. Different minerals form different types and colors of crystals inside the geodes.
Archimedes’ Principle
Archimedes’ Principle is a law of physics regarding buoyancy. The principle states, “The buoyant force applied by the fluid is equal to the weight of the displaced fluid. Essentially, when an object is immersed fully or partially in a fluid, the upward force applied by the fluid on the object is the same as the weight of the fluid displaced by the object.” We can apply Archimedes’ Principle with the equation W(air) / (w(air)-W(water)) to determine how much of the geode is solid and how much is hollow.
Key Takeaways
Archimedes’ Principle explained (explanation of the principle technically begins around 5:54, but the additional information about fluids at rest leading up to it is helpful to have a better understanding of Archimedes’ Principle):
Weathering, Erosion, and Deposition
Weathering is the breakdown of rocks on Earth’s surface. There are two types of weathering:
After the rocks are broken down through weathering, erosion can occur. Erosion is the process by which the small bits of rock are transported to a new location. Finally, deposition occurs when the particles are added to or deposited at a new location. These three processes act as a cycle, continually breaking down and building up different parts of Earth’s landscape.
Key Takeaway
Weathering is the making the mess and Erosion is cleaning it up.
Sand
Sand is any rocky material that is bigger in size than silt and smaller than gravel. Sand is created when rocks are weathered, or broken down, in one of two ways: by water or by wind. When wind or water continually passes over a rock, it breaks it down into smaller and smaller pieces and sand is formed. Sand that was formed from weathering by wind tends to be pitted and frosted in appearance because other grains of sand have constantly been pelted against the rock. Sand that was formed from weathering by water tends to be smooth and polished because the water has continually passed over the rock.
Where did this sand come from?
Type of Sand | Location | Characteristics |
Weathering by wind | Dunes in the desert | Scratched or frosted, pitted, uniform in size |
Weathering by water | Rocks near water | Rounded, polished, smooth |
Like fossils, sand can also tell a story. Based on where it is found in the world, sand is composed of different materials. Thus, it can also come in a variety of colors such as black, white, green, red and pink. Black sand, for example, is made from lava that has cooled to form an igneous rock; one place it can be found is near volcanoes in Hawaii.
10
Follow this link to take the earth science final quiz. The information on this quiz will be on the final exam. You will get immediate feedback on your answers.
III
11
Weather vs. Climate
Weather is the short-term atmospheric conditions in an area like, “It’s raining” or “It’s sunny today”. As such, weather can change day to day.
Climate is the usual weather activity that can be expected for an area and time of year such as, “Minnesota is so snowy during the winter” or “Florida is sunny in the summer”. Climate is measured in 30-year intervals, so the term climate change refers to the continual change of the climate over time from what is typically expected to happen.
Some people confuse weather and climate. For example, you may hear something like, “This snowstorm is crazy…we need global warming!” However, this statement confuses weather and climate. A snowstorm that lasts for a few days is a weather event; global warming is part of climate change which is measured over decades. Earth could have its hottest day on record–a weather event–but we cannot call that climate change unless a trend indicating a change in temperature can be measured over a 30-year period.
Key Takeaways
12
Earth’s Atmosphere
Earth’s atmosphere is a layer of gases, mainly nitrogen and oxygen, between Earth’s surface and space. From space, the atmosphere can be seen as a thin blue line around Earth’s circumference in the image below.
The atmosphere is relatively thin, 60 miles wide, but it plays an important role for the planet. It lets in heat from the Sun so Earth has a livable temperature, while also acting a shield to block much of the Sun’s harmful radiation. When Earth’s systems are in balance, the atmosphere is a key part of regulating temperature, weather, and climate.
Certain gases in Earth’s atmosphere are called greenhouse gases. Like a greenhouse, they let sunlight through to reach the surface of Earth and then trap its heat in the atmosphere. The most abundant greenhouse gases are:
Greenhouse gases are complex molecules made of three or more atoms bonded together. Gases move quickly and collide with other molecules in the atmosphere. This causes greenhouse gas molecules to vibrate and have an asymmetrical shape.
Because of this asymmetrical shape, they can absorb infrared radiation from the Sun. Then, the radiation is released back into the atmosphere which helps keep the planet warm enough to support life. Other gases in Earth’s atmosphere such as nitrogen and oxygen are more abundant, but they do not absorb infrared radiation because their molecular structure stays symmetrical.
The Greenhouse Effect
Watch the following video for a short explanation of carbon dioxide and the greenhouse effect.
The greenhouse effect describes how greenhouse gases in Earth’s atmosphere trap heat.
When infrared radiation from the Sun reaches Earth:
Watch the animation, below, to see the greenhouse effect in action.
The greenhouse effect is a key part of Earth’s natural processes. Without heat from the Sun’s radiation and the atmosphere’s protection, Earth’s temperature would not be regulated to support life. However, the greenhouse effect can go too far when Earth’s systems are out of balance.
Earth’s atmosphere can be compared to a blanket that is wrapped around the planet; the planet needs this blanket to survive in outer space. But when there are too many greenhouse gases in the atmosphere (from burning fossil fuels, for example), they radiate more heat than normal. This causes Earth’s blanket to get thicker and thicker and global temperature increases. Unfortunately, Earth cannot simply take the blanket off in order to cool down. Over time, this leads to our current situation: global climate change with wide-reaching and serious consequences.
Albedo Effect
Albedo is the amount of energy reflected by a surface. Light surfaces tend to have a high albedo because they reflect more energy. Dark surfaces tend to have a low albedo because they absorb more energy.
As seen in the image, below, the Sun’s rays project solar radiation to Earth’s surface. Lighter-colored surfaces such as ice reflect the radiation. Darker-colored surfaces such as land and water absorb the Sun’s heat.
Currently, Earth’s albedo is decreasing as a result of climate change. As ice melts at the poles and glaciers, it is replaced by land and water. Because of their darker colors, land and water have low albedo–they absorb radiation which increases Earth’s temperature and leads to increased ice melt. This relationship, a positive feedback loop, is shown in the image below.
Key Takeaways
The Carbon Cycle
Carbon is an abundant element that is critical for life on Earth. As seen in the image, below, carbon naturally moves between the atmosphere, land, and water in the carbon cycle. Most of Earth’s carbon is stored in rocks and sediments, but also in the oceans and in the atmosphere.
Carbon dioxide, a greenhouse gas, is important for life on Earth. For example, it traps heat to regulate Earth’s temperature and is a key component of photosynthesis, the process by which plants create their own food. Due to human activities, however, carbon dioxide is increasing to abnormally high levels in the atmosphere and causing Earth’s temperature to heat up.
The following video shows the global carbon cycle, how carbon dioxide in Earth’s atmosphere fluctuates and moves around the globe over the course of a year.
What is ppm?
Carbon dioxide in the atmosphere is measured in parts per million (ppm).
So, if the CO2 concentration is 400 ppm, that means 400 molecules out of every one million gas molecules in the atmosphere are carbon dioxide.
Scientists use ice cores, samples of ice drilled from ice sheets and glaciers, to gather data about carbon dioxide levels over time. The Law of Superposition and the Law of Original Horizontality can be applied to ice cores as well: Older layers of ice are compacted and trapped beneath newer layers over time. Within each layer, bubbles of carbon dioxide are trapped; this provides scientists with a record of atmospheric levels of carbon dioxide going back hundreds of thousands of years. Scientists can also use this data to create climate models which help predict future climate change.
The graph, below, was created using ice core data. As shown in the graph, carbon dioxide levels on Earth have naturally fluctuated for hundreds of thousands of years. Still, CO2 levels were relatively stable within a certain range and never exceeded 300 ppm.
At the far right side of the graph, there is a sharp uptick in CO2 levels, indicating the rise of fossil fuel use. By 2017, the average was 405 ppm. NASA’s most recent data from July 2019 measured 411 ppm of CO2 in the atmosphere. All of this data indicates that Earth’s systems are out of balance from typical patterns that have been established over millennia.
13
Climate Change
Fast Facts:
At the most basic level, climate change is a significant change over a 30-year period from the typical or expected weather patterns of an area. Earth’s climate has always fluctuated; the difference now is that Earth is experiencing significant climate change in a much shorter time period–decades rather than millions of years.
Climate change is human-caused. Since the rise of industrialization in the 19th century, humans have relied more and more on fossil fuels for energy. However, fossil fuels release a significant amount of greenhouse gases, especially carbon dioxide, into the air when they are burned. This has led to a rapid rise in global temperature as well as many other significant changes to Earth’s natural balance.
The video, below, shows Earth’s temperature increase between 1880 and 2017.
Tipping Points: The Point of No Return
Human caused climate change is not a new idea.
Despite decades of warnings and scientific data, human-caused climate change has severely escalated. Atmospheric carbon dioxide has massively increased leading to higher global temperatures and a multitude of other serious consequences for the planet.
Recently, scientists have warned that we are near to reaching a tipping point, a place of irreversible damage where abnormal and extreme climate change conditions become the norm. Some climate models predict that Earth could reach a tipping point by 2060 if significant action is not taken to reduce greenhouse gas emissions and other human factors that accelerate climate change.
Global Impact of Climate Change
Due to climate change, Earth’s systems are out of balance. Global systems have more energy than normal and climate change events are often amplified by each other. This creates a positive feedback loop which has wide-ranging effects. including more extreme temperatures, more extreme weather events, melting sea ice, glacier retreat, sea level rise, and ecosystem disruption.
Watch the video, below, for a quick overview of the impacts of climate change.
More Extreme Temperatures
Climate change is not just global warming. Although Earth’s climate is heating up overall, climate change leads to increased frequency and intensity of temperature–a weather event–at both the high and low range of the spectrum.
For example, July 2019 was the hottest month on record globally. On the map, below, the pink and red shading indicates areas that had warmer than average temperatures.
On the other hand, climate change can also cause extreme and abnormally cold temperatures. As seen in the images below, the polar vortex–a system of freezing wind and air–split from its normal position over the Arctic in January 2019. The vortex, now unstable, caused the jet stream to warp from its normal pattern. This pushed extremely cold Arctic air down to the midwestern United States while areas of Alaska experienced warm weather. While the polar vortex is an example of weather, not climate, it is likely that the planet will experience more frequent and unexpected temperature extremes such as this due to the effects of climate change.
More Extreme Weather Events
An increase in the frequency and intensity of extreme weather events is one way many people can observe and recognize climate change. The image, below, shows weather events that typically increase due to climate change. From left to right they are: heat waves, drought, hurricanes, wildfires, and melting sea ice.
The map, below, shows the cost per state in weather disasters causing $1 billion or more in damages between 1980 and 2019. In total, these disasters costed the U.S. more than $1.7 trillion, although different states were affected by different types of weather.
Click here to access the interactive map and see data for other states.
Melting Sea Ice
Temperatures at the North and South Poles are rising at twice the rate of the rest of the world due to melting ice and the albedo effect. This is an example of a positive feedback loop: As temperatures warm, more sea ice melts into water which absorbs solar radiation and causes temperatures to warm even further. The image, below, illustrates this positive feedback loop.
The photos, below, show the Bering and Chukchi Seas which are located in the northern Pacific Ocean between Alaska and Russia. These seas typically have maximum ice cover in late March and early April; as seen in the image on the left, most of the sea is covered in ice. Just five years later, the image on the right shows significantly less ice on the sea. In fact, 2019 had the lowest levels of ice on record for this region.
Ice has a higher albedo than water so it reflects the Sun’s rays back into the atmosphere. When sea ice melts, darker-colored seawater absorbs the sun’s radiation which heats the oceans. Higher ocean temperatures negatively affect plants and living creatures in marine ecosystems which affects marine-based economic industries, such as fishing, in turn.
Glacier Retreat
Glaciers are large bodies of snow and ice that move slowly across land. Glaciers naturally fluctuate in size with the seasons, but climate change has led to warmer temperatures overall. This means that glaciers melt at a faster rate than snow falls to rebuild the glacier’s mass, a phenomenon called glacier retreat. Melting glaciers affects the ecosystem of an area because different plants and animals will not be able to survive in a changing landscape. Additionally, humans rely on typical ice melt from glaciers as a critical water source which dwindles when glaciers retreat.
For example, when Montana’s Glacier National Park was created in 1910, it had 150 glaciers. Today, only 26 remain and they are all significantly smaller than their original size. The image, below, shows the significant retreat of the Boulder Glacier. Today, the glacier is so small it is considered inactive. Click here to see more images of glacier retreat.
Sea Level Rise
The main cause of sea level rise is thermal expansion. When water is heated, its volume increases. Picture a pot of water boiling on the stove: When the liquid water heats, it expands and turns to steam which has a larger volume.
The same thing happens with water in the ocean. As Earth’s temperature increases due to climate change, the oceans are absorbing 90% of the increased heat. As the temperature of the ocean increases, its volume increases so sea level rises.
Watch the following video for more explanation of thermal expansion.
The second cause of sea level rise is ice melt from land. As global temperatures rise, ice sheets and glaciers are melting at increasingly fast rates. However, it is important to note that only ice melt from Antarctica and other land masses contributes to sea level rise.
Like Antarctica, ice melting off of Greenland contributes to sea level rise because Greenland is an island. Watch the following short video for further explanation.
Ecosystem Disruption
As the climate changes, the delicate balance of many ecosystems is disrupted or even destroyed. One example is coral reefs. Coral reefs play a critical role in the ocean ecosystem–they provide shelter for thousands of marine species, they regulate carbon dioxide levels in the ocean, they protect the shoreline from rough waters and storms, and they generate billions of dollars in revenue from fishing and tourism.
Coral reefs are severely impacted by climate change. Scientists estimate that more than a quarter of coral reefs have died worldwide in the last three decades. Read the infographic below to learn more about coral reefs and climate change.
Climate Change in Iowa ppt 7.1
General trends from climate change in Iowa
-More rain, warmer winters, hundred-year floods
Based on data which has been peer-reviewed by thousands of scientists, researchers and educators from colleges and universities across Iowa release an annual Iowa Climate Statement each year. According to the Iowa Climate Statement 2019, “Dangerous Heat Events Will Be More Frequent and Severe”. Click here to access the one-page report.
Previous topics have included the impact of climate change on Iowa agriculture, droughts in Iowa, humidity and heat, and calls to politicians to address climate change. Click here to access previous Iowa climate statements.
Misinformation and Doubt
Among scientists, there is nearly universal consensus that human-caused climate change is occurring and it has serious ramifications for life on Earth. Nonetheless, there is still widespread misinformation and doubt about global climate change.
Politics/Economics-Resistance to climate science and data, fake news/science
What is Being Done?
Paris Climate Agreement ppt 8.2
What individuals can do
Educate yourself
14
Warm and cold fronts
A warm front is the boundary where a warmer air mass is moving in to replace a cooler air mass; the air behind a warm front is warmer than the area it is moving into.
A cold front is the boundary where a cooler air mass is moving in to replace a warmer air mass; the air behind a cold front is cooler than the area it is moving into.
Pressure systems
The air pressure on Earth changes throughout the day which affects the weather of an area. A high or low pressure system indicates higher or lower pressure than what is typical for an area. In general, air moves from high pressure areas to low pressure areas.
In a low pressure system, there is less pressure on Earth’s surface so air rises. The rising air carries water vapor into the atmosphere which forms clouds and leads to precipitation. As such, a low pressure system is associated with more volatile weather conditions such as clouds, rain, and wind.
In a high pressure system, there is more pressure on Earth’s surface so air descends. Consequently, fewer clouds form. Therefore, the weather is typically sunny and clear in a high pressure system.
A red line indicates a warm front. The circles point in the direction that the front is moving.
A blue line indicates a cold front. The triangles point in the direction that the front is moving.
A line that alternates blue and red indicates a stationary front–an area where a warm and cold front meet, but neither replaces the other.
A blue H is used to indicate a high pressure system. A red L is used to indicate a low pressure system.
On the weather map, below, different symbols are used to indicate weather conditions across the United States.
This saying has been used to predict the weather for many years; similar sayings have even been quoted in the Bible and Shakespeare’s plays. However, this saying is also scientifically accurate.
Light from the Sun is made of all the colors of the rainbow. Picture the arc of a rainbow: The red wavelengths on the outside are longer and the blue wavelengths on the inside are shorter. On a typical day, the blue light is scattered and reflected by particles in the atmosphere most efficiently because it travels in shorter wavelengths. This is why the sky is blue.
A high pressure system is associated with good weather. However, the air is filled with dust and aerosols because the air is pushed down closer to the surface of Earth. These particles scatter long red wavelengths through the atmosphere more efficiently than blue wavelengths which gives the sky a red appearance at sunrise and sunset.
“Red sky at night, sailor’s delight.”
In the middle latitudes, between 30 and 60 degrees, weather generally moves from west to east. The Sun sets in the west, so a red sky at night indicates that good weather will be moving toward you the next day.
“Red sky at morning, sailors take warning.”
The Sun rises in the east, so a red sky in the morning indicates that the good weather has already passed. Therefore, a low pressure system, and bad weather, will likely be moving in next.
Carbon Cycle
Within the carbon cycle, there are two interconnected subcycles. One is dealing with the rapid carbon exchange with living organisms. The other one is dealing with long-term cycling of carbon through geologic processes. In this cycle, carbon dioxide goes through make changes. Photosynthesis can convert carbon dioxide gas into organic carbon. Also, when matter from living organisms are buried deep underground, they become fossilized which is a form of long-term storage of organic carbon.
Biogeochemical cycles by OpenStax College CC by 4.0; modification of work by John M. Evans and Howard Perlman, USGS
Water Cycle
Although it may seem to change, the amount of water on Earth is actually constant. However, the water’s physical state and its location change in a process called the water cycle.
Key Terms in the Water Cycle
For more explanation, watch the following video from Khan Academy:
Wind
Wind is caused when Earth’s surface is heated unevenly by the Sun. Different types of surfaces on Earth, such as land or water, absorb heat differently. Additionally, darker-colored areas absorb more heat than lighter-colored surfaces. Finally, Earth is tilted on its axis so the Sun hits certain areas of the surface more directly than others which causes temperature differences. All of these factors contribute to the uneven heating of Earth’s surface.
Remember that warm air rises and cool air descends. When warm air rises, it leaves a low pressure area behind. In order to maintain balance, air from a cooler, high-pressure area moves in to fill the space and wind occurs.
15
The link below is a guide to use while watching Before the Flood (2016). This is not required for class, but can be used as an additional resource.
Click here to access and download the watching guide.
“The Garden of Earthly Delights” by Hieronymus Bosch is public domain
16
Follow this link to take the climate science practice quiz. You will get immediate feedback on your answers.
IV
In addition to the content presented in the first three sections, pedagogy for science teachers is an important part of this course. This section includes the following chapters:
17
Key ideas of pedagogy in this class
The following TED Talk discusses the history of our education system, current issues in education, and ways we can reform education to be more relevant for the future. This video is highly recommended viewing.
Misconceptions
18
Five Good Reasons to Use Science Notebooks
Gilbert, J. & Kotelma, M. (2005). Five good reasons to use science notebooks. Science and Children, November/December, 28-32.
Harvard-Smithsonian Center for Astrophysics. (1987). A private universe [Video documentary]. Retrieved from https://vimeo.com/113349804
Introduction to Earth/Space Science
National Research Council (2012). A framework for k-12 science education: Practices, crosscutting concepts, and core Ideas. Washington, DC: The National Academies Press. https://doi.org/10.17226/13165.
Rutherford, F. J. (1990). The physical setting. In Science for all Americans online (Chapter 4). Retrieved from http://www.project2061.org/publications/sfaa/ online/chap4.htm
Stepans, J. I., Beiswenger, R. E., & Dyche, S. (1986). Misconceptions die hard. The Science Teacher, September, 65-69.
Watson, B. & Konicek, R. (1990). Teaching for conceptual change: Confronting children’s experience. Phi Delta Kappan, May, 35-40.
Environmental Education–School of the Wild
Braus, J.A. & Wood, D. (1993). Environmental education in the schools: Creating a program that works. Peace Corps Information Collection and Exchange. 4-13.
19
Next Generation Science Standards (NGSS)
Science Methods 2 YouTube Channel
1