Ch 1: Introduction to Earth Science
LEARNING OUTCOMES
- Develop an understanding of scientific knowledge and inquiry.
- Describe the basic model of the scientific method and how scientists use it to understand the natural world.
- Explain the importance of understanding location.
- Compare and contrast the various types of geospatial technologies used today.
Earth science is the study of our home planet and all of its components: its lands, waters, atmosphere, and interior. In this book, some chapters are devoted to the processes that shape the lands and impact people. Other chapters depict the processes of the atmosphere and its relationship to the planet’s surface and all our living creatures. For as long as people have been on the planet, humans have had to live within Earth’s boundaries. Now human life is having a profound effect on the planet. Several chapters are devoted to the effect people have on the planet.
The journey to better understanding Earth begins here with an exploration of how scientists learn about the natural world and will introduce you to the study of Earth science.
The journey to better understanding Earth begins here with an exploration of how scientists learn about the natural world and will introduce you to the study of Earth science.
Scientific Inquiry
Science is a path to gaining knowledge about the natural world. The study of science also includes the body of knowledge that has been collected through scientific inquiry. To conduct a scientific investigation, scientists ask testable questions that can be systematically observed and careful evidence collected. Then they use logical reasoning and some imagination to develop a testable idea, called a hypothesis, along with explanations to explain the idea. Finally, scientists design and conduct experiments based on their hypotheses.
Scientists seek to understand the natural world by asking questions and then trying to answer the questions with evidence and logic. A scientific question must be testable and supported by empirical data, it does not rely on faith or opinion. Our understanding of natural Earth processes helps us to understand why earthquakes occur where they do and how to understand the consequences of adding excess greenhouse gases into the atmosphere.
Scientific research may be done to build knowledge or to solve problems and lead to scientific discoveries and technological advances. Pure research often aids in the development of applied research. Sometimes the results of pure research may be applied long after the pure research was completed. Sometimes something unexpected is discovered while scientists are conducting their research. Some ideas are not testable. For example, supernatural phenomena, such as stories of ghosts, werewolves, or vampires, cannot be tested. Scientists describe what they see, whether in nature or in a laboratory.
Science is the realm of facts and observations, not moral judgments. Scientists might enjoy studying tornadoes, but their opinion that tornadoes are exciting is not important to learn about them. Scientists increase our technological knowledge, but science does not determine how or if we use that knowledge. Scientists learned to build an atomic bomb, but scientists didn’t decide whether or when to use it. Scientists have accumulated data on warming temperatures; their models have shown the likely causes of this warming. But although scientists are largely in agreement on the causes of global warming, they can’t force politicians or individuals to pass laws or change behaviors.
For science to work, scientists must make some assumptions. The rules of nature, whether simple or complex, are the same everywhere in the universe. Natural events, structures, and landforms have natural causes and evidence from the natural world can be used to learn about those causes. The objects and events in nature can be understood through careful, systematic study. Scientific ideas can change if we gather new data or learn more. An idea, even one that is accepted today, may need to be changed slightly or be entirely replaced if new evidence is found that contradicts it. Scientific knowledge can withstand the test of time because accepted ideas in science become more reliable as they survive more tests.
Scientists seek to understand the natural world by asking questions and then trying to answer the questions with evidence and logic. A scientific question must be testable and supported by empirical data, it does not rely on faith or opinion. Our understanding of natural Earth processes helps us to understand why earthquakes occur where they do and how to understand the consequences of adding excess greenhouse gases into the atmosphere.
Scientific research may be done to build knowledge or to solve problems and lead to scientific discoveries and technological advances. Pure research often aids in the development of applied research. Sometimes the results of pure research may be applied long after the pure research was completed. Sometimes something unexpected is discovered while scientists are conducting their research. Some ideas are not testable. For example, supernatural phenomena, such as stories of ghosts, werewolves, or vampires, cannot be tested. Scientists describe what they see, whether in nature or in a laboratory.
Science is the realm of facts and observations, not moral judgments. Scientists might enjoy studying tornadoes, but their opinion that tornadoes are exciting is not important to learn about them. Scientists increase our technological knowledge, but science does not determine how or if we use that knowledge. Scientists learned to build an atomic bomb, but scientists didn’t decide whether or when to use it. Scientists have accumulated data on warming temperatures; their models have shown the likely causes of this warming. But although scientists are largely in agreement on the causes of global warming, they can’t force politicians or individuals to pass laws or change behaviors.
For science to work, scientists must make some assumptions. The rules of nature, whether simple or complex, are the same everywhere in the universe. Natural events, structures, and landforms have natural causes and evidence from the natural world can be used to learn about those causes. The objects and events in nature can be understood through careful, systematic study. Scientific ideas can change if we gather new data or learn more. An idea, even one that is accepted today, may need to be changed slightly or be entirely replaced if new evidence is found that contradicts it. Scientific knowledge can withstand the test of time because accepted ideas in science become more reliable as they survive more tests.
Scientific Method
You have probably learned that the scientific method is a series of steps that help to investigate To answer those questions, scientists use data and evidence gathered from observations, experience, or experiments to answer their questions.
But scientific inquiry rarely proceeds in the same sequence of steps outlined by the scientific method. For example, the order of the steps might change because more questions arise from the data that is collected. Still, to come to verifiable conclusions, logical, repeatable steps of the scientific method must be followed. This video of The Scientific Method Made Easy explains the scientific method succinctly and well.
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SCIENTIFIC QUESTIONING
The most important thing a scientist can do is to ask questions.
SCIENTIFIC RESEARCH
To answer a question, a scientist first finds out what is already known about the topic by reading books and magazines, searching the Internet, and talking to experts. This information will allow the scientist to create a good experimental design. If this question has already been answered, the research may be enough or it may lead to new questions. Example: The farmer researches no-till farming on the Internet, at the library, at the local farming supply store, and elsewhere. He learns about various farming methods. He learns what type of fertilizer is best to use and what the best crop spacing would be. From his research, he learns that no-till farming can be a way to reduce carbon dioxide emissions into the atmosphere, which helps in the fight against global warming.
HYPOTHESIS
With the information collected from background research, the scientist creates a plausible explanation for the question. This is a hypothesis. The hypothesis must directly relate to the question and must be testable. Having a hypothesis guides a scientist in designing experiments and interpreting data. Example: The farmer’s hypothesis is this: No-till farming will decrease soil erosion on hills of similar steepness as compared to the traditional farming technique because there will be fewer disturbances to the soil.
DATA COLLECTION
To support or refute a hypothesis, the scientist must collect data. A great deal of logic and effort goes into designing tests to collect data so the data can answer scientific questions. Data is usually collected by experiment or observation. Sometimes improvements in technology will allow new tests to better address a hypothesis.
Observation is used to collect data when it is not possible for practical or ethical reasons to perform experiments. Written descriptions are qualitative data based on observations. This data may also be used to answer questions. Scientists use many different types of instruments to make quantitative measurements. Electron microscopes can be used to explore tiny objects or telescopes to learn about the universe. Probes make observations where it is too dangerous or too impractical for scientists to go. Data from the probes travel through cables or through space to a computer where it is manipulated by scientists.
Experiments may involve chemicals and test tubes, or they may require advanced technologies like a high-powered electron microscope or radio telescope. Atmospheric scientists may collect data by analyzing the gases present in gas samples, and geochemists may perform chemical analyses on rock samples.
A good experiment must have one factor that can be manipulated or changed. This is the independent variable. The rest of the factors must remain the same. They are the experimental controls. The outcome of the experiment, or what changes as a result of the experiment, is the dependent variable. The dependent variable “depends” on the independent variable.
Example: The farmer conducts an experiment on two separate hills. The hills have similar steepness and receive similar amounts of sunshine. On one, the farmer uses a traditional farming technique that includes plowing. On the other, he uses a no-till technique, spacing plants farther apart and using specialized equipment for planting. The plants on both hillsides receive identical amounts of water and fertilizer. The farmer measures plant growth on both hillsides. In this experiment:
Data gathered from advanced equipment usually goes directly into a computer, or the scientist may put the data into a spreadsheet. The data then can be manipulated. Charts and tables display data and should be clearly labeled. Statistical analysis makes more effective use of data by allowing scientists to show relationships between different categories of data. Statistics can make sense of the variability in a data set. Graphs help scientists to visually understand the relationships between data. Pictures are created so that other people who are interested can see the relationships easily.
In just about every human endeavor, errors are unavoidable. In a scientific experiment, this is called experimental error. What are the sources of experimental errors? Systematic errors may be inherent in the experimental setup so that the numbers are always skewed in one direction. For example, a scale may always measure one-half ounce high. The error will disappear if the scale is re-calibrated. Random errors occur because the measurement is not made precisely. For example, a stopwatch may be stopped too soon or too late. To correct this type of error, many measurements are taken and then averaged. If a result is inconsistent with the results from other samples and many tests have been done, it is likely that a mistake was made in that experiment and the inconsistent data point can be thrown out.
The most important thing a scientist can do is to ask questions.
- What makes Mount St. Helens more explosive and dangerous than the volcano on Mauna Loa, Hawaii?
- What makes the San Andreas fault different than the Wasatch Fault?
- Why does Earth have so many varied life forms but other planets in the solar system do not?
- What impacts could a warmer planet have on weather and climate systems?
SCIENTIFIC RESEARCH
To answer a question, a scientist first finds out what is already known about the topic by reading books and magazines, searching the Internet, and talking to experts. This information will allow the scientist to create a good experimental design. If this question has already been answered, the research may be enough or it may lead to new questions. Example: The farmer researches no-till farming on the Internet, at the library, at the local farming supply store, and elsewhere. He learns about various farming methods. He learns what type of fertilizer is best to use and what the best crop spacing would be. From his research, he learns that no-till farming can be a way to reduce carbon dioxide emissions into the atmosphere, which helps in the fight against global warming.
HYPOTHESIS
With the information collected from background research, the scientist creates a plausible explanation for the question. This is a hypothesis. The hypothesis must directly relate to the question and must be testable. Having a hypothesis guides a scientist in designing experiments and interpreting data. Example: The farmer’s hypothesis is this: No-till farming will decrease soil erosion on hills of similar steepness as compared to the traditional farming technique because there will be fewer disturbances to the soil.
DATA COLLECTION
To support or refute a hypothesis, the scientist must collect data. A great deal of logic and effort goes into designing tests to collect data so the data can answer scientific questions. Data is usually collected by experiment or observation. Sometimes improvements in technology will allow new tests to better address a hypothesis.
Observation is used to collect data when it is not possible for practical or ethical reasons to perform experiments. Written descriptions are qualitative data based on observations. This data may also be used to answer questions. Scientists use many different types of instruments to make quantitative measurements. Electron microscopes can be used to explore tiny objects or telescopes to learn about the universe. Probes make observations where it is too dangerous or too impractical for scientists to go. Data from the probes travel through cables or through space to a computer where it is manipulated by scientists.
Experiments may involve chemicals and test tubes, or they may require advanced technologies like a high-powered electron microscope or radio telescope. Atmospheric scientists may collect data by analyzing the gases present in gas samples, and geochemists may perform chemical analyses on rock samples.
A good experiment must have one factor that can be manipulated or changed. This is the independent variable. The rest of the factors must remain the same. They are the experimental controls. The outcome of the experiment, or what changes as a result of the experiment, is the dependent variable. The dependent variable “depends” on the independent variable.
Example: The farmer conducts an experiment on two separate hills. The hills have similar steepness and receive similar amounts of sunshine. On one, the farmer uses a traditional farming technique that includes plowing. On the other, he uses a no-till technique, spacing plants farther apart and using specialized equipment for planting. The plants on both hillsides receive identical amounts of water and fertilizer. The farmer measures plant growth on both hillsides. In this experiment:
- What is the independent variable?
- What are the experimental controls?
- What is the dependent variable?
Data gathered from advanced equipment usually goes directly into a computer, or the scientist may put the data into a spreadsheet. The data then can be manipulated. Charts and tables display data and should be clearly labeled. Statistical analysis makes more effective use of data by allowing scientists to show relationships between different categories of data. Statistics can make sense of the variability in a data set. Graphs help scientists to visually understand the relationships between data. Pictures are created so that other people who are interested can see the relationships easily.
In just about every human endeavor, errors are unavoidable. In a scientific experiment, this is called experimental error. What are the sources of experimental errors? Systematic errors may be inherent in the experimental setup so that the numbers are always skewed in one direction. For example, a scale may always measure one-half ounce high. The error will disappear if the scale is re-calibrated. Random errors occur because the measurement is not made precisely. For example, a stopwatch may be stopped too soon or too late. To correct this type of error, many measurements are taken and then averaged. If a result is inconsistent with the results from other samples and many tests have been done, it is likely that a mistake was made in that experiment and the inconsistent data point can be thrown out.
CONCLUSIONS
Scientists study graphs, tables, diagrams, images, descriptions, and all other available data to draw a conclusion from their experiments. Is there an answer to the question based on the results of the experiment? Was the hypothesis supported? Some experiments completely support a hypothesis and some do not. If a hypothesis is shown to be wrong, the experiment was not a failure. All experimental results contribute to knowledge. Experiments that do or do not support a hypothesis may lead to even more questions and more experiments.
Example: After a year, the farmer finds that erosion on the traditionally farmed hill is 2.2 times greater than erosion on the no-till hill. The plants on the no-till plots are taller and the soil moisture is higher. The farmer decides to convert to no-till farming for future crops. The farmer continues researching to see what other factors may help reduce erosion
Scientists study graphs, tables, diagrams, images, descriptions, and all other available data to draw a conclusion from their experiments. Is there an answer to the question based on the results of the experiment? Was the hypothesis supported? Some experiments completely support a hypothesis and some do not. If a hypothesis is shown to be wrong, the experiment was not a failure. All experimental results contribute to knowledge. Experiments that do or do not support a hypothesis may lead to even more questions and more experiments.
Example: After a year, the farmer finds that erosion on the traditionally farmed hill is 2.2 times greater than erosion on the no-till hill. The plants on the no-till plots are taller and the soil moisture is higher. The farmer decides to convert to no-till farming for future crops. The farmer continues researching to see what other factors may help reduce erosion
THEORY
As scientists conduct experiments and make observations to test a hypothesis, over time they collect a lot of data. If a hypothesis explains all the data and none of the data contradicts the hypothesis, the hypothesis becomes a theory. A scientific theory is supported by many observations and has no major inconsistencies. A theory must be constantly tested and revised. Once a theory has been developed, it can be used to predict behavior. A theory provides a model of reality that is simpler than the phenomenon itself. Even a theory can be overthrown if conflicting data is discovered. However, a longstanding theory that has lots of evidence to back it up is less likely to be overthrown than a newer theory.
As scientists conduct experiments and make observations to test a hypothesis, over time they collect a lot of data. If a hypothesis explains all the data and none of the data contradicts the hypothesis, the hypothesis becomes a theory. A scientific theory is supported by many observations and has no major inconsistencies. A theory must be constantly tested and revised. Once a theory has been developed, it can be used to predict behavior. A theory provides a model of reality that is simpler than the phenomenon itself. Even a theory can be overthrown if conflicting data is discovered. However, a longstanding theory that has lots of evidence to back it up is less likely to be overthrown than a newer theory.
Science does not prove anything beyond a shadow of a doubt. Scientists seek evidence that supports or refutes an idea. If there is no significant evidence to refute an idea and a lot of evidence to support it, the idea is accepted. The more lines of evidence that support an idea, the more likely it will stand the test of time. The value of a theory is when scientists can use it to offer reliable explanations and make accurate predictions.
Geographic Grid System
Geography is about spatial understanding, which requires an accurate grid system to determine absolute and relative location. Absolute location is the exact x- and y- coordinate on the Earth. Relative location is the location of something relative to other entities. For example, when you use your GPS in your smartphone or car, say Google Maps, you put in an absolute location. But as you start driving, the device tells you to turn right or left relative to objects on the ground: "Turn left on exit 202" is relative to the other exit points. Or if you give directions to your house, you often use relative locations to help them understand how to get to your house.
GREAT AND SMALL CIRCLES
Much of Earth's grid system is based on the location of the North Pole, South Pole, and the Equator. The poles are an imaginary line running from the axis of Earth's rotation. The plane of the equator is an imaginary horizontal line that cuts the earth into two equal halves. This brings up the topic of great and small circles. A great circle is any circle that divides the earth into a circumference of two equal halves. It's also the largest circle that can be drawn on a sphere. The line connecting any points along a great circle is also the shortest distance between those two points. Examples of great circles include the Equator, all lines of longitude, the line that divides the earth into day and night called the circle of illumination, and the plane of the ecliptic, which divides the earth into equal halves along the equator. Small circles are circles that cut the earth, but not into equal halves. Examples of small circles include all lines of latitude except the equator, the Tropical of Cancer, Tropic of Capricorn, the Arctic Circle, and the Antarctic Circle.
Much of Earth's grid system is based on the location of the North Pole, South Pole, and the Equator. The poles are an imaginary line running from the axis of Earth's rotation. The plane of the equator is an imaginary horizontal line that cuts the earth into two equal halves. This brings up the topic of great and small circles. A great circle is any circle that divides the earth into a circumference of two equal halves. It's also the largest circle that can be drawn on a sphere. The line connecting any points along a great circle is also the shortest distance between those two points. Examples of great circles include the Equator, all lines of longitude, the line that divides the earth into day and night called the circle of illumination, and the plane of the ecliptic, which divides the earth into equal halves along the equator. Small circles are circles that cut the earth, but not into equal halves. Examples of small circles include all lines of latitude except the equator, the Tropical of Cancer, Tropic of Capricorn, the Arctic Circle, and the Antarctic Circle.
 Image copyright: Pearson Scott Foresman, licensed under Creative Commons Attribution Share Alike 3.0
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 Image copyright: Pearson Scott Foresman, licensed under Creative Commons Attribution Share Alike 3.0
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LATITUDE AND LONGITUDE
Many think that latitude is a line connecting points on the earth and it's not. Latitude is actually an angular measurement north or south of the equator. So 30 degrees north means a point that is 30 degrees north of the equator. Latitude is also expressed in degrees, minutes, and seconds; 360 degrees in a circle, 60 minutes ( ' ) in a degree, and 60 seconds ( " ) in a minute. When you use Google Earth, the coordinate locations are in this degrees/minutes/seconds format. Latitude varies from 0 degrees (equator) to 90 degrees north and south (the poles).
A line connecting all points of the same latitude is called a parallel because the lines run parallel to each other. The only parallel that is also a great circle is the equator. All other parallels are small circles. The following are the most important parallel lines:
Many think that latitude is a line connecting points on the earth and it's not. Latitude is actually an angular measurement north or south of the equator. So 30 degrees north means a point that is 30 degrees north of the equator. Latitude is also expressed in degrees, minutes, and seconds; 360 degrees in a circle, 60 minutes ( ' ) in a degree, and 60 seconds ( " ) in a minute. When you use Google Earth, the coordinate locations are in this degrees/minutes/seconds format. Latitude varies from 0 degrees (equator) to 90 degrees north and south (the poles).
A line connecting all points of the same latitude is called a parallel because the lines run parallel to each other. The only parallel that is also a great circle is the equator. All other parallels are small circles. The following are the most important parallel lines:
- The Equator, 0 degrees
- Tropic of Cancer, 23.5 degrees N
- Tropic of Capricorn, 23.5 degrees S
- Arctic Circle, 66.5 degrees N
- Antarctic Circle, 66.5 degrees S
- The North Pole, 90 degrees N (infinitely small circle)
- The South Pole, 90 degrees S (infinitely small circle)
Latitude is also sometimes described as zones of latitude. Some of these zones of latitude include:
- Low latitude - generally between the equator and 30 degrees N
- Midlatitude - between 30 degrees and 60 degrees N and S
- High latitude - latitudes greater than about 60 degrees N and S
- Equatorial - within a few degrees of the equator
- Tropical - within the tropics (between 23.5 degrees N and 23.5 degrees S
- Subtropical - slightly pole-ward of the tropics, generally around 25-30 degrees N and S
- Polar - within a few degrees of the North or South Pole
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Longitude is the angular measurement east and west of the Prime Meridian (image on the right). Like latitude, longitude is measured in degrees, minutes, and seconds. Lines connecting equal points of longitude are called meridians. But unlike parallels, meridians do not run parallel to each other. Rather they are farthest apart from each other at the equator and merge toward each other toward the poles. The problem with longitude is that there isn't a natural baseline like the equator is for latitude. For over a hundred years, nations used their own "prime meridian" which proved problematic for trade. But in 1883 an international conference in Washington D.C. was held to determine a global prime meridian. After weeks of debate, the Royal Observatory at Greenwich, England was determined as the Greenwich Meridian or also called the prime meridian for the world. So today, longitude starts at the Prime Meridian and measures east and west of that line. At 180 degrees of the Prime Meridian in the Pacific Ocean is the International Date Line. The line determines where the new day begins in the world. Now because of this, the International Date Line is not actually a straight line, rather it follows national borders so that a country isn't divided into two separate days (and we think hour time zones are a pain). If you look at the map above, the International Date Line is to the right in a dark, black line. Note how it is drawn to make sure nations are not divided by the International Date Line.
Image copyright: CIA Fact Book 2010, licensed under Creative Commons Public Domain
TIME ZONES
This is also a good time to take a look at time zones around the world. If you refer back to the map above, you can see the different time zones in various colors. Since the earth rotates 360 degrees in a 24 hour period, the earth rotates 15 degrees every hour creating 24 time zones. In an ideal world, each time zone would follow lines of longitude every 15 degrees (7.5 degrees in each direction from the center of the time zone). But because of political boundaries, time zones are not divided up so perfectly and vary greatly in shape and width.
Greenwich, England was chosen in the mid-nineteenth century as the starting point of time worldwide. The reason was that at the time, England was the superpower of the time both militarily and economically. So the meridian that ran through Greenwich became zero degrees or the prime meridian. Because of the earth’s rotation in reference to the prime meridian, locations east of the new meridian meant time was ahead while locations west of the meridian were behind in time in reference to Greenwich, England.
Ultimately, when you combine parallel and meridian lines, you end up with a geographic grid system that allows you to determine your exact location on the planet.
This is also a good time to take a look at time zones around the world. If you refer back to the map above, you can see the different time zones in various colors. Since the earth rotates 360 degrees in a 24 hour period, the earth rotates 15 degrees every hour creating 24 time zones. In an ideal world, each time zone would follow lines of longitude every 15 degrees (7.5 degrees in each direction from the center of the time zone). But because of political boundaries, time zones are not divided up so perfectly and vary greatly in shape and width.
Greenwich, England was chosen in the mid-nineteenth century as the starting point of time worldwide. The reason was that at the time, England was the superpower of the time both militarily and economically. So the meridian that ran through Greenwich became zero degrees or the prime meridian. Because of the earth’s rotation in reference to the prime meridian, locations east of the new meridian meant time was ahead while locations west of the meridian were behind in time in reference to Greenwich, England.
Ultimately, when you combine parallel and meridian lines, you end up with a geographic grid system that allows you to determine your exact location on the planet.
Geospatial Technology
Data, data, data… data is everywhere. It’s collected every time you go to the grocery store and use their card to reduce the costs when you click on a link on Facebook, or when you do any kind of search on a search engine like Google, Bing, or Yahoo!. It is used by your state department of transportation when you are driving on a freeway or when you use an app on a smartphone. Futurists believe that in the near future, face recognition technology will allow a sales representative to know what types of clothes you like to buy based on a database of your recent purchases at their store and others.
Now there are two basic types of data you need to know: spatial and non-spatial data. Spatial data, also called geospatial data, is data that can be linked to a specific location on Earth. Geospatial data is becoming “big business” because it isn’t just data, but data that can be located, tracked, patterned, and modeled based on other geospatial data. Census information that is collected every 10 years is an example of spatial data. Non-spatial data is data that cannot be specifically traced to a specific location. This might include the number of people living in a household, enrollment within a specific course, or gender information. But non-spatial data can easily become spatial data if it can be linked in some way to a location. Geospatial technology specialists have a method called geocoding that can be used to give non-spatial data a geographic location. Once data has a spatial component associated with it, the type of questions that can be asked dramatically changes.
Now there are two basic types of data you need to know: spatial and non-spatial data. Spatial data, also called geospatial data, is data that can be linked to a specific location on Earth. Geospatial data is becoming “big business” because it isn’t just data, but data that can be located, tracked, patterned, and modeled based on other geospatial data. Census information that is collected every 10 years is an example of spatial data. Non-spatial data is data that cannot be specifically traced to a specific location. This might include the number of people living in a household, enrollment within a specific course, or gender information. But non-spatial data can easily become spatial data if it can be linked in some way to a location. Geospatial technology specialists have a method called geocoding that can be used to give non-spatial data a geographic location. Once data has a spatial component associated with it, the type of questions that can be asked dramatically changes.
REMOTE SENSING
Remote sensing can be defined as a human’s ability to study objects without being in direct physical contact with them. So for example, your eyes are a form of passive remote sensing because they are “passively” absorbing electromagnetic energy within the visible spectrum from distant objects and your brain is processing that energy into information. There are a variety of remote sensing platforms or devices, but they can basically be categorized into the following that we will look at throughout the course. Satellite imagery is a type of remotely sensed imagery taken of the Earth's surface, which is produced from orbiting satellites that gather data via electromagnetic energy. Next is areal photography, which is film-based or digital photographs of the Earth, usually from an airplane or non-piloted drone. Images are either taken from a vertical or oblique position. The third is radar, which is an interesting form of remote sensing technology that uses microwave pulses to create imagery of features on Earth. This can be from a satellite image or ground-based Doppler radar for weather forecasting. Finally, a fast-growing realm of remote sensing is called Light Detection and Ranging or Lidar, which is a form of remote sensing that measures the distance of objects using laser pulses of light.
Remote sensing can be defined as a human’s ability to study objects without being in direct physical contact with them. So for example, your eyes are a form of passive remote sensing because they are “passively” absorbing electromagnetic energy within the visible spectrum from distant objects and your brain is processing that energy into information. There are a variety of remote sensing platforms or devices, but they can basically be categorized into the following that we will look at throughout the course. Satellite imagery is a type of remotely sensed imagery taken of the Earth's surface, which is produced from orbiting satellites that gather data via electromagnetic energy. Next is areal photography, which is film-based or digital photographs of the Earth, usually from an airplane or non-piloted drone. Images are either taken from a vertical or oblique position. The third is radar, which is an interesting form of remote sensing technology that uses microwave pulses to create imagery of features on Earth. This can be from a satellite image or ground-based Doppler radar for weather forecasting. Finally, a fast-growing realm of remote sensing is called Light Detection and Ranging or Lidar, which is a form of remote sensing that measures the distance of objects using laser pulses of light.
Image copyright: GPS.gov, licensed under Creative Commons Public Domain
GLOBAL POSITIONING SYSTEMS
Another type of geospatial technology is global positioning systems (GPS) and a key technology for acquiring accurate control points on Earth’s surface. Now to determine the location of that GPS receiver on Earth’s surface, a minimum of four satellites is required using a mathematical process called triangulation. Normally the process of triangulation requires a minimum of three transmitters, but because the energy sent from the satellite is traveling at the speed of light, minor errors in calculation could result in large location errors on the ground. Thus, a minimum of four satellites is often used to reduce this error. This process using the geometry of triangles to determine location is used not only in GPS, but a variety of other location needs like finding the epicenter of earthquakes.
A user can use a GPS receiver to determine their location on Earth through a dynamic conversation with satellites in space. Each satellite transmits orbital information called the ephemeris using a highly accurate atomic clock along with its orbital position called the almanac. The receiver will use this information to determine its distance from a single satellite using the equation D = rt, where D = distance, r = rate or the speed of light (299,792,458 meters per second), and t = time using the atomic clock. The atomic clock is required because the receiver is trying to calculate distance, using energy that is transmitted at the speed of light. Time will be fractions of a second and requires a “time clock” up to the utmost accuracy.
Another type of geospatial technology is global positioning systems (GPS) and a key technology for acquiring accurate control points on Earth’s surface. Now to determine the location of that GPS receiver on Earth’s surface, a minimum of four satellites is required using a mathematical process called triangulation. Normally the process of triangulation requires a minimum of three transmitters, but because the energy sent from the satellite is traveling at the speed of light, minor errors in calculation could result in large location errors on the ground. Thus, a minimum of four satellites is often used to reduce this error. This process using the geometry of triangles to determine location is used not only in GPS, but a variety of other location needs like finding the epicenter of earthquakes.
A user can use a GPS receiver to determine their location on Earth through a dynamic conversation with satellites in space. Each satellite transmits orbital information called the ephemeris using a highly accurate atomic clock along with its orbital position called the almanac. The receiver will use this information to determine its distance from a single satellite using the equation D = rt, where D = distance, r = rate or the speed of light (299,792,458 meters per second), and t = time using the atomic clock. The atomic clock is required because the receiver is trying to calculate distance, using energy that is transmitted at the speed of light. Time will be fractions of a second and requires a “time clock” up to the utmost accuracy.
There is a technology that exists that can bring together remote sensing data, GPS data points, spatial and non-spatial data, and spatial statistics into a single, dynamic system for analysis and that is a geographic information system (GIS). A GIS is a powerful database system that allows users to acquire, organize, store, and most importantly analyze information about the physical and cultural environments. A GIS views the world as overlaying physical or cultural layers, each with quantifiable data that can be analyzed. A single GIS map of a national forest could have layers such as elevation, deciduous trees, evergreens, soil type, soil erosion rates, rivers and tributaries, major and minor roads, forest health, burn areas, regrowth, restoration, animal species type, trails, and more. Each of these layers would contain a database of information specific to that layer.
Nearly every discipline, career path, or academic pursuit uses geographic information systems because of the vast amount of data and information about the physical and cultural world. Disciplines and career paths that use GIS include: conservation, ecology, disaster response and mitigation, business, marketing, engineering, sociology, demography, astronomy, transportation, health, criminal justice and law enforcement, travel and tourism, news media, and the list could endlessly go on.
Now, GIS primarily works from two different spatial models: raster and vector. Raster based GIS models are images much like a digital picture. Each image is broken down into a series of columns and rows of pixels and each pixel is georeferenced to somewhere on Earth's surface is represents a specific numeric value - usually a specific color or wavelength within the electromagnetic spectrum. Look at this website to review electromagnetic radiation. Most remote sensing images come into a GIS as a raster layer. The other type of GIS model is called a vector model. Vector-based GIS models are based on the concept of points that are again georeferenced (i.e. given an x-, y-, and possibly z- location) to somewhere specific on the ground. From points, lines can be created by connecting a series of points and areas can be created by closing loops of vector lines. For each of these vector layers, a database of information can be attributed to it. So for example, a vector line of rivers could have a database associated with it such as length, width, streamflow, government agencies responsible for it, and anything else the GIS user wants to be tied to it. What these vector models represent is also a matter of scale. For example, a city can be represented as a point or a polygon depending on how zoomed in you are on the location. A map of the world would show cities as points, whereas a map of a single county may show the city as a polygon with roads, populations, pipes, or grid systems within it.
Summary
Nearly every discipline, career path, or academic pursuit uses geographic information systems because of the vast amount of data and information about the physical and cultural world. Disciplines and career paths that use GIS include: conservation, ecology, disaster response and mitigation, business, marketing, engineering, sociology, demography, astronomy, transportation, health, criminal justice and law enforcement, travel and tourism, news media, and the list could endlessly go on.
Now, GIS primarily works from two different spatial models: raster and vector. Raster based GIS models are images much like a digital picture. Each image is broken down into a series of columns and rows of pixels and each pixel is georeferenced to somewhere on Earth's surface is represents a specific numeric value - usually a specific color or wavelength within the electromagnetic spectrum. Look at this website to review electromagnetic radiation. Most remote sensing images come into a GIS as a raster layer. The other type of GIS model is called a vector model. Vector-based GIS models are based on the concept of points that are again georeferenced (i.e. given an x-, y-, and possibly z- location) to somewhere specific on the ground. From points, lines can be created by connecting a series of points and areas can be created by closing loops of vector lines. For each of these vector layers, a database of information can be attributed to it. So for example, a vector line of rivers could have a database associated with it such as length, width, streamflow, government agencies responsible for it, and anything else the GIS user wants to be tied to it. What these vector models represent is also a matter of scale. For example, a city can be represented as a point or a polygon depending on how zoomed in you are on the location. A map of the world would show cities as points, whereas a map of a single county may show the city as a polygon with roads, populations, pipes, or grid systems within it.
Summary
Earth Science is the study of our home planet and all of its components: its lands, waters, atmosphere, and interior. Like other sciences, Earth science is a science that is grounded in scientific knowledge using the scientific method as the fundamental way to understand the environment.
Earth scientists, geographers, and all spatial scientists require a strong background in understanding the way humans have partitioned the earth to determine location. In order to do that, a series of lines representing angular measurements on the earth was established, known as the geographic grid system. Once that has been done, spatial knowledge can be collected and analyzed based on geographic or spatial data. This allows us to understand spatial concepts of patterns, distributions and flows based on location and spatial boundaries.
Often times this geographic data must be collected and analyzed using a high-tech and dynamic technology called geospatial technology. This technology encompasses powerful remote sensing technology, global positioning systems, and geographic information systems.
Earth scientists, geographers, and all spatial scientists require a strong background in understanding the way humans have partitioned the earth to determine location. In order to do that, a series of lines representing angular measurements on the earth was established, known as the geographic grid system. Once that has been done, spatial knowledge can be collected and analyzed based on geographic or spatial data. This allows us to understand spatial concepts of patterns, distributions and flows based on location and spatial boundaries.
Often times this geographic data must be collected and analyzed using a high-tech and dynamic technology called geospatial technology. This technology encompasses powerful remote sensing technology, global positioning systems, and geographic information systems.
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