What is the world ocean and how is it explored?

What is the world ocean and how is it explored? By: Mr. D’Angelone

Learning Objectives • Students will describe the world ocean. • Students will explain what is meant by oceanography. • Students will describe three ways scientists explore the oceans. By: Mr. D'Angelone

Key Terms • world ocean • oceanography • sonar • submersible By: Mr. D'Angelone

The Water Planet • About 75 percent of Earth's surface is covered with water. • Most of this is salt water. • This large body of salt water is known as the world ocean. • Earth is the only planet in the solar system that has a covering of liquid water. By: Mr. D'Angelone

Because of its great amounts of liquid water, Earth is often known as the blue planet. By: Mr. D'Angelone

Divisions of the World Ocean • The world ocean is divided into three major bodies of salt water, also called oceans. • These are the Atlantic Ocean, the Pacific Ocean, and the Indian Ocean. • The word sea is sometimes used as another name for ocean. • It also refers to a smaller body of water connected to or near an ocean. • A gulf is a large area of ocean, larger than a bay, reaching into land. By: Mr. D'Angelone

The World Ocean By: Mr. D'Angelone

Size and Depth • The Pacific Ocean is the largest of the world's oceans. • More than half of Earth's ocean water is in the Pacific Ocean. • The Pacific is also Earth's deepest ocean. • Its average depth is 4.3 km (2.6 mi). • The Atlantic Ocean is the second largest ocean. • Several seas and gulfs are part of the Atlantic Ocean. • Its average depth is 3.3 km (2.0 mi). By: Mr. D'Angelone

Size and Depth (2) • The Indian Ocean is the smallest ocean. • It is deeper than the Atlantic Ocean, but not as deep as the Pacific. • The average depth of the Indian Ocean is 3.8 km (2.3 mi). By: Mr. D'Angelone

Oceanography • The study of Earth's oceans is called oceanography. • Scientists who study the oceans and ocean life are called oceanographers. • An oceanographer might specialize in the study of the oceans' depths, coral reefs, or the geography of the ocean floor. By: Mr. D'Angelone

Deep-Sea Drilling • Samples of rock from the ocean floor can be obtained by drilling. • Studying these samples allows scientists to learn more about the ocean floor. • The Deep Sea Drilling Project (DSDP) was an important ocean research program that ended in 1983. (Glomar Challenger) • The DSDP was replaced in 1985 by another program called the Ocean Drilling Program (ODP). (JOIDES Resolution) By: Mr. D'Angelone

Sonar • Scientists can map the ocean floor by using sonar. • The word sonar comes from the letters in sound navigation and ranging. • Sonar is an echo-sounding system. • Sound waves travel through water at about 1,500 m/s. • A transmitter bounces a sound wave off the ocean floor. By: Mr. D'Angelone

Sonar (2) • The returning sound wave, or echo, is picked up by a receiver. • Scientists can measure the time it takes for the sound wave to return. • This number can be used to calculate the depth of the ocean floor. By: Mr. D'Angelone

Sonar uses echoes of sound waves. By: Mr. D'Angelone

Submersibles • Scientists also study the oceans by traveling in underwater research vessels called submersibles. • One of the first submersibles to be developed was a bathysphere. • The bathysphere remained attached to the research ship. • Therefore, its movements were limited. By: Mr. D'Angelone

Submersibles (2) • Another kind of submersible is called a bathyscaph. • A bathyscaph is not attached to anything. • It can hold one pilot and two scientists. • Robot submersibles equipped with under water cameras can reach great depths and stay there for long periods of time. By: Mr. D'Angelone

A Bathyscaph By: Mr. D'Angelone

Checking Concepts • About how much of Earth's surface is covered with water? • What are the three major oceans? • Which of Earth's oceans is the deepest? By: Mr. D'Angelone

Answers • 75% • Atlantic, Pacific, and Indian • The Pacific By: Mr. D'Angelone

The End

What is the world ocean and how is it explored?