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From the maps you use when traveling, to the weather report you use when deciding whether or not to carry an umbrella, Earth science is part of your everyday life.
Astronomy The study of objects beyond Earth’s atmosphere is called astronomy. Prior to the invention of sophisticated instruments, such as the telescope shown in Figure 1.1, many astronomers merely described the locations of objects in space in relation to each other. Today, Earth scientists study the universe and everything in it, including galaxies, stars, planets, and other bodies they have identified. You studied units based on astronomy in Grade 6 and Grade 9 Science.
Meteorology The study of the forces and processes that cause the atmosphere to change and produce weather is meteorology. Meteorologists also try to forecast the weather and learn how changes in weather over time might affect Earth’s climate. You studied a unit based on meteorology in Grade 5 and Grade 10 Science.
Geology The study of the materials that make up Earth, the processes that form and change these materials, and the history of the planet and its lifeforms since its origin is the branch of Earth science known as geology. Geologists identify rocks, study glacial movements, interpret clues to Earth’s 4.6-billion-year history, and determine how forces change our planet. You studied geology based units all the way through, but especially in Grade 7.
Oceanography The study of Earth’s oceans, which cover nearly three-fourths of the planet, is called oceanography. Oceanographers study the creatures that inhabit salt water, measure different physical and chemical properties of the oceans, and observe various processes in these bodies of water. When oceanographers are conducting field research, they often have to dive into the ocean to gather data, as shown in Figure 1.2. If you took 11 Oceans, you have definitely been exposed to oceanography! :)
Environmental science The study of the interactions of organisms and their surroundings is called environmental science. Environmental scientists study how organisms impact the environ- ment both positively and negatively. The topics an environmental scientist might study include natural resources, pollution, alternative energy sources, and the impact of humans on the atmosphere. You have had exposure to this growing field of science all the way through your education!
Subspecialties The study of our planet is a broad endeavor, and as such, each of the five major areas of Earth science consists of a variety of subspecialties, some of which are listed in Table 1.1.
Earth’s Systems
Scientists who study Earth have identified four main Earth systems: the geosphere, atmosphere, hydrosphere, and biosphere. Each system is unique, yet each interacts with the others.
Geosphere The area from the surface of Earth down to its center is called the geosphere. The geosphere is divided into three main parts: the crust, mantle, and core. These three parts are illustrated in Figure 1.3.
The rigid outer shell of Earth is called the crust. There are two kinds of crust - continental crust and oceanic crust. Just below the crust is Earth’s mantle. The mantle differs from the crust both in composition and behavior. The mantle ranges in temperature from 100°C to 4000°C - much warmer than the temperatures found in Earth’s crust. Below the mantle is Earth’s core. You will learn more about the crust, mantle, and core in a later unit.
Atmosphere The blanket of gases that surrounds our planet is called the atmosphere. Earth’s atmosphere contains about 78 percent nitrogen and 21 percent oxygen. The remaining 1 percent of gases in the atmosphere include water vapor, argon, carbon dioxide, and other trace gases. Earth’s atmosphere provides oxygen for living things, protects Earth’s inhabitants from harmful radiation from the Sun, and helps to keep the planet at a temperature suitable for life.
Hydrosphere All the water on Earth, including the water in the atmosphere, makes up the hydrosphere. About 97 percent of Earth’s water exists as salt water, while the remaining 3 percent is freshwater contained in glaciers, lakes and rivers, and beneath Earth’s surface as groundwater. Only a fraction of Earth’s total amount of freshwater is in lakes and rivers.
Biosphere The biosphere includes all organisms on Earth as well as the environments in which they live. Most organisms live within a few meters of Earth’s surface, but some exist deep beneath the ocean’s surface, and others live high atop Earth’s mountains. All of Earth’s lifeforms require interaction with at least one of the other systems for their survival.
As illustrated in Figure 1.4, Earth’s biosphere, geosphere, hydrosphere, and atmosphere are interdependent systems. For example, Earth’s present atmosphere formed millions of years ago through interactions with the geosphere, hydrosphere, and biosphere. Organisms in the biosphere, including humans, continue to change the atmosphere through their activities and natural processes. It is all connected, ...systems within a larger system.
Technology
The study of science, including Earth science, has led to many discoveries that have been applied to solve society’s needs and problems. The application of scientific discoveries is called technology. Technology is transferable, which means that it can be applied to new situations. Freeze-dried foods, ski goggles, and the ultralight materials used to make many pieces of sports equipment were created from technologies used in space programs. Technology is not used only to make life easier. It can also make life safer. Most people have smoke detectors in their houses to help warn them if there is a fire. Smoke detectors were also invented as part of a space program and were adapted for use in everyday life.
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