1.1 - Introduction to Earth Science_May

1.1 - Introduction to Earth Science

Lesson Objectives

  • Identify and describe the five branches of Earth science.
  • Differentiate between the Earth’s four systems.
  • Explain how Earth's four systems are interdependent.


  • astronomy
  • geology
  • meteorology
  • oceanography
  • environmental science
  • biosphere
  • hydrosphere
  • atmosphere
  • geosphere
  • interdependent


Earth science is the study of all aspects of our planet Earth.  Earth science is not just about the molten lava, icy mountain peaks, steep canyons and towering waterfalls of the continents. Earth science includes the atmosphere and oceans. The field also looks out into the solar system, galaxy, and universe.   Earth science is a combination science that draws upon all other sciences to unlock Earth’s mysteries.

Earth as seen from Apollo 17

Earth as seen from Apollo 17.

Different branches of Earth science study one particular part of Earth.  Since all of the branches are connected, specialists work together to answer complicated questions.  Let’s look at the five main branches of Earth science.


Geology is the study of the materials that make up Earth, the processes that form and change these materials, and Earth’s history.  Geologists study how rocks and minerals form and the way mountains rise up and erode away.  There are many other branches of geology.  There is so much to know about our home planet that most geologists become specialists in one area.  For example, a mineralogist studies minerals, as seen below.  

(A) Mineralogists focus on all kinds of minerals. (B) Seismographs are used to measure earthquakes and pinpoint their origins.

Volcanologists brave molten lava to study volcanoes. Seismologists monitor earthquakes worldwide to help protect people and property from harm.  Paleontologists are interested in fossils and how ancient organisms lived.  Scientists who compare the geology of other planets to Earth are planetary geologists.  Some geologists study the Moon, others look for petroleum, and still others specialize in studying soil.  Some geologists study how old rocks are and determine how different rock layers formed.  Geologists might study rivers and lakes, the underground water found between soil and rock particles, or even water that is frozen in glaciers.  Earth scientists also need geographers who explore the features of Earth’s surface and work with cartographers, who make maps.  Studying the layers of rock beneath the surface helps us to understand the history of planet Earth.  There is probably an expert in almost anything you can think of related to Earth!

These folded rock layers have bent over time. Studying rock layers helps scientists to explain these layers and the geologic history of the area.


Oceanography is the study of the oceans.  More than 70% of Earth’s surface is covered with water, and almost all of that water is in the oceans.  Scientists have visited the deepest parts of the ocean in submarines.  Remote vehicles go where humans cannot, yet much of the ocean remains unexplored.  Some people call the ocean “the last frontier.”

This research vessel is specially designed to explore the seas around Antarctica.

There are many branches of oceanography.  Physical oceanography is the study of water movement, like waves and ocean currents.  Marine geology looks at rocks and structures in the ocean basins.  Chemical oceanography studies the natural elements in ocean water.  Marine biology looks at marine life.

Humans have had a big impact on the oceans.  Populations of fish and other marine species have been overfished. Contaminants are polluting the waters.  Global warming is melting the thick ice caps and warming the water.  Warmer water expands and, along with water from the melting ice caps, causes sea levels to rise.


Meteorologists don’t study meteors — they study the atmosphere, the thin layer of gas that surrounds the Earth.  The word “meteor” refers to things in the air.  Meteorology includes the study of weather patterns, climate, clouds, hurricanes, and tornadoes.  Using radar and satellites, meteorologists work to predict, or forecast, the weather.  Some scientists, called climatologists, work to understand the climate as it is now and to predict how the climate may change in the future.

Meteorologists can help us to prepare for major storms or know if today is a good day for a picnic.

Environmental Science

Environmental science is the study of the interactions of living things and their surroundings as well as their impact on the Earth.  Environmental scientists hope to find better ways of living that can also help the environment. The topics an environmental scientist might study include natural resources, pollution, alternative energy sources, and the impact of humans on Earth’s systems.

In a marine ecosystem, coral, fish, and other sea life depend on each other for survival.


Astronomy is the study of objects beyond the Earth’s atmosphere.  Earth scientists study the universe and everything in it, including galaxies, stars, planets, and the electromagnetic spectrum.

Astronomy and astronomers have shown that the planets in our solar system are not the only planets in the universe.  The universe also contains black holes, other galaxies, asteroids, comets, and nebulae. As big as Earth seems, the entire universe is vastly more enormous. Earth is just a tiny part of our universe.

Astronomers use many tools to study things in space. Earth-orbiting telescopes view stars and galaxies from the darkness of space. They may have optical and radio telescopes to see things that the human eye can't see. Spacecrafts travel great distances to send back information on faraway places.

Scientists are using telescopes to search for other planets that may have conditions favorable for life. The places they can look are near our solar system in our galaxy.

Subspecialties of Earth Science

Major Area of StudySubspecialtySubjects Studied
AstronomyAstrophysicsPhysics of the universe, including the physical properties of objects found in space
Planetary sciencePlanets of the solar system and the processes that form them
MeteorologyClimatologyPatterns of weather over a long period of time
Atmospheric chemistryChemistry of Earth's atmosphere, and the atmospheres of other planets
GeologyPaleontologyRemains of organisms that once lived on Earth; ancient environments
GeochemistryEarth's composition and the processes that change it
OceanographyPhysical oceanographyPhysical characteristics of oceans, such as salinity, waves, and currents
Marine geologyGeologic features of the ocean floor, including plate tectonics of the ocean
Environmental ScienceEnvironmental soil scienceInteractions between humans and the soil, such as impact of farming practices, the effects of pollution on soil, plants, and groundwater
Environmental chemistryChemical alterations to the environment through pollution and natural means

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[a] others.  


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 the diagram below.


The solid, semi-solid, and liquid land of the geosphere form layers that are physically and[b] chemically different. If someone were to cut through Earth to its center, these layers would be revealed like the layers of an onion (see image above). The outermost layer of the geosphere consists of loose soil rich in nutrients, oxygen, and silicon. Beneath that layer lies a very thin, solid crust of oxygen and silicon. Next is a thick, semi-solid mantle of oxygen, silicon, iron, and magnesium. Below that is a liquid outer core of nickel and iron. At the center of Earth is a solid inner core of nickel and iron.


The blanket of gases that surrounds our planet is called the atmosphere.   It extends from less than 1 m below the planet's surface to more than 10,000 km above the planet's surface.  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.


The hydrosphere contains all the solid, liquid, and gaseous water of the planet.  The hydrosphere extends from Earth's surface downward several kilometers into the lithosphere and upward about 12 kilometers into the atmosphere.

A small portion of the water in the hydrosphere is fresh.  This water flows as precipitation from the atmosphere down to Earth's surface, as rivers and streams along Earth's surface, and as groundwater beneath Earth's surface.  Most of Earth's fresh water, however, is frozen.

Ninety-seven percent of Earth's water is saltwater.  The saltwater collects in deep valleys along Earth's surface.  These large collections of saltwater are referred to as oceans.  Water near the poles is very cold, while water near the equator is very warm.  The differences in temperature cause water to change physical states.  Extremely low temperatures like those found at the poles cause water to freeze into a solid such as a polar icecap, a glacier, or an iceberg.  Extremely high temperatures like those found at the equator cause water to evaporate into a gas.


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 life-forms require interaction with at least one of the other systems for their survival.  

Earth’s biosphere, geosphere, hydrosphere, and atmosphere are interdependent systems.  Interdependence means there is mutual reliance or relationship between each entity; each system depends on one another and is affected by changes to the others.   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.  In fact, the spheres are so closely connected that a change in one sphere often results in a change in one or more of the other spheres.  Interactions between the systems are happening constantly, in many different ways.

Lesson Summary

  • Earth science includes many fields of science related to our home planet.
  • Geology is the study of Earth's materials and structures and the processes that create them.
  • Oceanography is the study of the oceans: water movement, chemistry and the ocean basins among other things.
  • Meteorologists study the atmosphere including climate and weather.
  • Environmental science is the study of the interactions of living things and their surroundings as well as their impact on the Earth.
  • Astronomers study Earth's larger environment: the solar system, galaxy, and universe that our planet resides in.
  • The Earth is made up of four interdependent spheres.

Lesson Review Questions

1. What are the five major branches of Earth science?

2. What branch of science deals with stars and galaxies beyond Earth?

3. List a topic of study from each branch of Earth science.

4. What does a meteorologist study?

5. A glacier is melting. What are all of the scientists you can think of who might be involved in studying this glacier? What would each of them do?

6. Design an experiment that you could conduct in any branch of Earth science. Identify the independent variable and dependent variable.





All other images came from David Johnson book.

Video link to include or embed: https://www.youtube.com/watch?v=jxbIJH4fTYo&feature=youtu.be 




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