What is Earth Science?
For thousands of years, people have looked at the world around them and wondered what forces shaped it. Throughout history, many cultures have been terrified and fascinated by seeing volcanoes erupt, feeling the ground shake during an earthquake, or watching the sky darken during an eclipse.
Some cultures developed myths or stories to explain these events. In some of these myths, angry goddesses hurled fire from volcanoes, and giants shook the ground by wrestling underneath the Earth’s surface. Modern science searches for natural causes and uses careful observations to explain these same events and to understand Earth and its changing landscape.
The Scientific Study of Earth
The scientific study of Earth began with careful observations. Scientists in China began keeping records of earthquakes as early as 780 BCE. The ancient Greeks compiled a catalog of rocks and minerals around 200 BCE. Other ancient peoples, including the Maya, tracked the movements of the sun, the moon, and the planets at observatories like the one shown in Figure 1. The Maya used these observations to create accurate calendars.
For many centuries, scientific discoveries were limited to observations of phenomena that could be seen with the unaided eye. Then, in the 16th and 17th centuries, the inventions of the microscope and the telescope made seeing previously hidden worlds possible.
Eventually, the body of knowledge about Earth became known as Earth science.
Earth science is the study of Earth and the universe around it. Earth science, like other sciences, assumes that the causes of natural events, or phenomena, can be discovered through careful observation and experimentation.
OBJECTIVES
▸ Describe two cultures that contributed to modern scientific study.
▸ Name the four main branches of Earth science.
► Discuss how Earth scientists help us understand the world around us.
KEY TERMS
- Earth science
- Geology
- Oceanography
- Meteorology
- Astronomy
- Earth science is the scientific study of Earth and the universe around it. Geology is the scientific study of the origin, history, and structure of Earth and the processes that shape Earth.
- Oceanography is the scientific study of the ocean, including the properties and movements of ocean water, the characteristics of the ocean floor, and the organisms that live in the ocean.
- Meteorology is the scientific study of Earth’s atmosphere, especially about weather and climate.
- Astronomy is the scientific study of the universe.
What is Earth Science, Branches of Earth Science
The ability to make observations improves when technology, such as new processes or equipment, is developed. Technology has allowed scientists to explore the ocean depths, Earth’s unseen interior, and the vastness of space. Earth scientists have used technology and hard work to build an immense body of knowledge about Earth.
Most Earth scientists specialize in one of four major areas of study: the solid Earth, the oceans, the atmosphere, and the universe beyond Earth. Examples of Earth scientists working in these areas are shown.
Geology
The study of the origin, history, processes, and structure of the solid Earth is called geology. Geology includes many specialized areas of study. Some geologists explore Earth’s crust for deposits of coal, oil, gas, and other resources. Other geologists study the forces within Earth to predict earthquakes and volcanic eruptions. Some geologists study fossils to learn more about Earth’s past. Often, new knowledge forms new areas of study.
Oceanography
Oceans cover nearly three-fourths of Earth’s surface. The study of Earth’s oceans is called oceanography. Some oceanographers work on research ships that are equipped with special instruments for studying the sea. Other oceanographers study waves, tides, and ocean currents. Some oceanographers explore the ocean floor to obtain clues to Earth’s history or to locate mineral deposits.
Meteorology
The study of Earth’s atmosphere is called meteorology. Using satellites, radar, and other technologies, meteorologists study the atmospheric conditions that produce weather. Many meteorologists work as weather observers and measure factors such as wind speed, temperature, and rainfall. This weather information is then used to prepare detailed weather maps. Other meteorologists use weather maps, satellite images, and computer models to make weather forecasts. Some meteorologists study climate, the patterns of weather that occur over long periods.
Astronomy
The study of the universe beyond Earth is called astronomy. Astronomy is one of the oldest branches of Earth science. The ancient Babylonians charted the positions of planets and stars nearly 4,000 years ago. Modern astronomers use Earth-based and space-based telescopes as well as other instruments to study the sun, the moon, the planets, and the universe. Technologies such as rovers and space probes have also provided astronomers with new information about the universe.
Environmental Science
Other Earth scientists study how humans interact with their environment. This relatively new field of Earth science is called environmental science. Environmental scientists study many issues, such as the use of natural resources, pollution, and the health of plant and animal species on Earth. Some environmental scientists study the effects of industries and technologies on the environment.
⇒ Connection to HISTORY
Scientific Revolutions ⇒
Throughout history, many cultures have added to scientific knowledge. Over the last few centuries, global exploration and cultural exchanges have helped modern science change very quickly. During this time, science has aided the industrialization of countries around the world. Technology has also allowed humans to explore areas from the deep-ocean basins to the universe beyond Earth.
Advances in science usually occur through small additions to existing knowledge. The daily work of scientists and engineers normally results in step-by-step increases of understanding and improvements in the ability to meet human needs. In this way, scientists add knowledge, invent new technologies, and educate future generations of scientists.
However, some advances in science and technology occur very quickly and have effects that ripple through science and society. When a scientific advance completely changes the way that scientists think about the universe, a scientific revolution occurs. Scientific revolutions cause long-held ideas to be challenged and put aside for new ways of thinking and viewing the universe.
Examples of recent scientific revolutions include Darwin‘s theory of evolution, the concept of quantum mechanics, and Einstein’s general theory of relativity. Progress in science and technology can be affected by social issues and challenges.
In some cases, both scientists and nonscientists resist letting go of long-held beliefs. Many of the ideas that Einstein replaced with his theory of relativity had been in place for hundreds of years. Through many years of continued research and education, revolutionary ideas often become accepted by the scientific community and by society as a whole.
But even revolutionary ideas are continuously being tested. In 2002, experiments were performed aboard NASA’s Cassini spacecraft to test a part of Einstein’s theory of relativity. Using new technologies, scientists were able to verify Einstein’s theory, which had been proposed almost 100 years earlier.
The Importance of Earth Science
Natural forces not only shape Earth but also affect life on Earth. For example, a volcanic eruption may bury a town under ash. An earthquake may produce huge ocean waves that destroy shorelines. By understanding how natural forces shape our environment, Earth scientists, can better predict potential disasters and help save lives and property.
The work of Earth scientists also helps us understand our place in the universe. Astronomers studying distant galaxies have come up with new ideas about the origins of our universe. Geologists studying rock layers have found clues to Earth’s past environments and the evolution of life on this planet.
Earth provides the resources that make life as we know it possible. Earth also provides the materials to enrich the quality of people’s lives. The fuel that powers a jet, the metal used in surgical instruments, and the paper and ink in this book all come from Earth’s resources. The study of Earth science can help people gain access to Earth’s resources, but Earth scientists also strive to help people use those resources wisely.
Science as a Process
Art, architecture, philosophy, and science are all forms of human endeavor. Although artists, architects, and philosophers may use science in their work, science does not have the same goals as other human endeavors do.
The goal of science is to explain natural phenomena. Scientists ask questions about natural events and then work to answer those questions through experiments and examination. Scientific understanding moves forward through the work of many scientists, who build on the research of the generations of scientists before them.
The behavior of Natural Systems
Scientists start with the assumption that nature is understandable. Scientists also expect that similar forces in a similar situation will cause similar results. However, the forces involved in natural events are complex. For example, changes in temperature and humidity can cause rain in one city, but the same changes in temperature and humidity may cause fog in another city. These different results might be due to differences in the two cities or due to complex issues, such as differences in climate.
Scientists also expect that nature is predictable, which means that the future behavior of natural forces can be anticipated. So, if scientists understand the forces and materials involved in a process, they can predict how that process will evolve. The scientists study ice cores in Antarctica.
Ice cores can provide clues to Earth’s past climate changes. Because natural systems are complex, however, a high level of understanding and predictability can be difficult to achieve. To increase their understanding, scientists follow the same basic processes of studying and describing natural events.
OBJECTIVES
▸ Explain how science is different from other forms of human endeavor.
▸ Identify the steps that make up scientific methods.
▸ Analyze how scientific thought changes as new information is collected.
▸ Explain how science affects society.
KEY TERMS
- Observation hypothesis
- Independent variable
- Dependent variable
- Peer review theory
Scientists use ice cores to study past compositions of Earth’s atmosphere. This information can help scientists learn about past climate changes.
- Observation is the process of obtaining information by using the senses; the information is obtained by using the senses.
- A hypothesis is an idea or explanation that is based on observations and that can be tested.
- Peer review is the process in which experts in a given field examine the results and conclusions of a scientist’s study before that study is accepted for publication
Scientific Methods
Over time, the scientific community has developed organized and logical approaches to scientific research. These approaches are known as scientific methods. Scientific methods are not a set of sequential steps that scientists always follow. Rather, these methods are guidelines for scientific problem-solving.
Ask a Question
Scientific methods often begin with observations. Observation is the process of using the senses of sight, touch, taste, hearing, and smell to gather information about the world. When you see thunderclouds form in the summer sky, you are making an observation. And when you feel cool, smooth, polished marble or hear the roar of river rapids, you are making observations.
Observations can often lead to questions.
What causes tornadoes to form?
Why is oil discovered only in certain locations?
What causes a river to change its course?
Simple questions such as these have fueled years of scientific research and have been investigated through scientific methods.
Form a Hypothesis
Once a question has been asked and basic information has been gathered, a scientist may propose a tentative answer, which is also known as a hypothesis (hie PAHTH uh sis). A hypothesis (plural, hypotheses) is a possible explanation or solution to a problem. Hypotheses can be developed through close and careful observation. Most hypotheses are based on known facts about similar events.
One example of a hypothesis is that houseplants given a large amount of sunlight will grow faster than plants given a smaller amount of sunlight. This hypothesis could be made by observing how and where other plants grow.
Test the Hypothesis
After a hypothesis is proposed, it is often tested by performing experiments. An experiment is a procedure that is carried out according to certain guidelines. Factors that can be changed in an experiment are variables. Independent variables are factors that can be changed by the person experimenting. Dependent variables are variables that change as a result of a change in independent variables.
In most experiments, only one independent variable is tested. For example, to test how sunlight affects plants, a scientist would grow identical plants. The plants would receive the same amount of water and fertilizer but different amounts of sunlight. Thus, sunlight would be the independent variable. How the plants respond to the different amounts of sunlight would be the dependent variable.
Most experiments include a control group. A control group is a group that serves as a standard of comparison with another group to which the control group is identical except for one factor. In this experiment, the plants that receive a natural amount of sunlight would be the control group. An experiment that contains a control is called a controlled experiment. Most scientific experiments are controlled experiments.
Draw Conclusions
After many experiments and observations, a scientist may reach conclusions about his or her hypothesis. If the hypothesis fits the known facts, it may be accepted as true. If the experimental results differ from what was expected, the hypothesis may be changed or discarded. Expected and unexpected results lead to new questions and further study. The results of scientific inquiry may also lead to new knowledge and new methods of inquiry that further scientific aims.
Independent variable in an experiment, the factor that is deliberately manipulated dependent variable in an experiment, the factor that changes as a result of manipulation of one or more other factors (the independent variables)
Quick LAB
Making Observations Procedure 5 min
- Get an ordinary candle of any shape and color.
- Record all the observations you can make about the candle.
- Light the candle with a match, and watch it burn for 1 minute.
- Record as many observations about the burning candle as you can.
- When you are finished, extinguish the flame. Record any observations.
Analysis
- Share your results with your class.
- How many things that your classmates observed did you not observe?
- Explain this phenomenon.
Scientific Measurements and Analysis
During an experiment, scientists must gather information. An important method of gathering information is measurement. Measurement is the comparison of some aspect of an object or event with a standard unit.
Scientists around the world can compare and analyze each other’s measurements because scientists use a common system of measurement called the International System of Units, or SL. This system includes standard measurements for length, mass, temperature, and volume. All SI units are based on intervals of 10. The Reference Tables section of the Appendix contains a chart of SI units.
Accuracy and Precision
Accuracy and precision are important in scientific measurements. Accuracy refers to how close a measurement is to the true value of the thing being measured. Precision is the exactness of the measurement. For example, a distance measured in millimeters is more precise than a distance measured in centimeters. Measurements can be precise and yet inaccurate. The relationship between accuracy and precision is shown in Figure.
Quick LAB (15 min)
Sample Size and Accuracy Procedure
- Shuffle a deck of 52 playing cards eight times.
- Lay out 10 cards. Record the number of red cards.
- Reshuffle, and repeat step 2 four more times.
- Which trials showed the highest number and lowest number of red cards?
- Calculate the total range of red cards by finding the difference between the highest number and the lowest number.
- Determine the mean number of red cards per trial by adding the number of red cards in the five trials and then dividing by 5.
Analysis
- A deck of cards has 50% red cards. How close is your average to the percentage of red cards in the deck?
- Pool the results of your classmates. How close is the new average to the percentage of red cards in the deck?
- How does changing the sample size affect accuracy?
Error
Error is an expression of the amount of imprecision or variation in a set of measurements. Error is commonly expressed as a percentage error or as a confidence interval. Percentage error is the percentage of deviation of an experimental value from an accepted value.
A confidence interval describes the range of values for a set percentage of measurements. For example, imagine that the average length of all of the ears of corn in a field is 23 cm, and 90% of the ears are within 3 cm of the average length. A scientist may report that the average length of all of the ears of corn in a field is 23 ± 3 cm with 90% confidence.
Observations and Models
In Earth science, using controlled experiments to test a hypothesis is often impossible. When experiments are impossible, scientists make additional observations to gather evidence. The hypothesis is then tested by examining how well the hypothesis fits or explains all of the known evidence.
Scientists also use models to simulate conditions in the natural world. A model is a description, representation, or imitation of an object, system, process, or concept. Scientists use several types of models. Physical models are three-dimensional models that can be touched. Maps and charts are examples of graphical models.
Conceptual models are verbal or graphical models that represent how a system works or is organized. Mathematical models are mathematical equations that represent the way a system or process works.
Most recently, scientists have developed computer models, which can be used to represent simple processes or complex systems. After a good computer model has been created, scientists can perform experiments by manipulating variables much as they would when performing a physical experiment.
MATH PRACTICE
Percentage Error Percentage error is calculated by using the following equation:
Percent error=(accepted value- experimental value) accepted value × 100
If the accepted value for the weight of a gallon of water is 3.78 kg and the measured value is 3.72 kg, what is the percentage error for the measurement? Show your work.
Acceptance of Scientific Ideas
When scientists conclude, they introduce their findings to the scientific community. New scientific ideas undergo review and testing by other scientists before the ideas are accepted.
Publication of Results and Conclusions
Scientists commonly present the results of their work in scientific journals or at professional meetings. Results published in journals are usually written in a standard scientific format. Many journals are now being published online to allow scientists quicker access to the results of other scientists.
Peer Review
Scientists in any one research group tend to view scientific ideas similarly. Therefore, they may be biased in their experimental design or data analysis. To reduce bias, scientists submit their ideas to other scientists for peer review. Peer review is the pro- cess in which several experts on a given topic review another expert’s work on that topic before the work gets published.
These experts determine if the results and conclusions of the study merit publication. Peer reviewers commonly suggest improvements to the study, or they may determine that the results or conclusions are flawed and recommend that the study not be published.
Scientists follow an ethical code that states that only valid experimental results should be published. The peer review process serves as a filter, which allows only well-supported ideas to be published.
Formulating a Theory
After results are published, they usually lead to more experiments, which are designed to test and expand the original idea. This process may continue for years until the original idea is disproved, modified, or generally accepted. Sometimes, elements of different ideas are combined to form concepts that are more complete.
When an idea has undergone much testing and reaches general acceptance, that idea may help form a theory. A theory is an explanation that is consistent with all existing tests and observations. Theories are often based on scientific laws.
A scientific law is a general statement that describes how the natural world behaves under certain conditions and for which no exceptions have been found. Like theories, laws are discovered through scientific research. Theories and scientific laws can be changed if conflicting information is discovered in the future.
The Importance of Interdisciplinary Science
Scientists from many disciplines commonly contribute the information necessary to support an idea. The free exchange of ideas between fields of science allows scientists to identify explanations that fit a wide range of scientific evidence. When an explanation is supported by evidence from a variety of fields, the explanation is more likely to be accurate.
New disciplines of science sometimes emerge as a result of new connections that are found between more than one branch of science. An example of the development of a widely accepted hypothesis that is based on interdisciplinary evidence is shown in Figure 7.
Science and Society
Scientific knowledge helps us understand our world. The work of people, including scientists, is influenced by their cultural and personal beliefs. Science is a part of society, and advances in science can have important and long-lasting effects on both science and society. Examples of these far-reaching advances include the theory of plate tectonics, quantum mechanics, and the theory of evolution.
Science is also used to develop new technology, including new tools, machines, materials, and processes. Sometimes, technologies are designed to address a specific human need. In other cases, technology is an indirect result of science that was directed at another goal. For example, technology that was designed for space exploration has been used to improve computers, cars, medical equipment, and airplanes.
However, new technology may also create new problems. Scientists involved in research that leads to new technologies must consider the possible negative effects of their work. Before making technology decisions, people should consider the alternatives, risks, costs, and benefits to humans and Earth. Even after such decisions are made, society often continues to debate them.
For example, the Alaskan pipeline transports oil. However, the transport of oil in the United States is part of an ongoing debate about how we use oil resources and how these uses affect our natural world.
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