Note: Items marked with a star (*) are linked to the glossary*. If you want to know the meaning of a word marked with a star (*), just click on the word and look for its definition.

• What is remote sensing?
• What is remote sensing used for?

Information can be collected about the land using special cameras and instruments located: 

• just a few feet above the Earth's surface, 
• from an airplane flying hundreds to thousands of feet above the ground, 
• or even from a satellite*orbiting hundreds of miles above the Earth! 

By measuring the amount of time it takes sound to travel from the ship to the seafloor and back to the ship, and how much the sounds bounces back, we can make a picture of the seafloor. 

Pictures taken by special cameras on airplanes and satellites and by sonar systems on shipsare called remotely sensed images*. These images are often collected as digital files. This allows us to use computers to improve and analyze the images.

• large forest firescan be mapped from space, allowing rangers to see a much larger area than from the ground

• tracking clouds to help predict the weatheror watcherupting volcanos, and help watch forduststorms

• tracking thegrowth of a city,andchanges in farmland or forests over several years or even decades

• mapping the ocean bottom. Mountains, volcanos, and canyons that are higher, bigger, and deeper than any on land exist on the ocean floor!

• can you think of other uses of remote sensing*? 

• for what would you want to use satellite* or sonar* pictures?

Some examples are: 

• cameras on satellites and airplanes take pictures of large areas of the Earth's surface, allowing us to see much more than we can standing on the ground

• sonar systems on ships can be used to create images of the ocean floor without needing to travel to the bottom of the ocean

• cameras on satellites can be used to make pictures of temperature changes in the oceans - an impossibly long task if we had to travel all over the ocean in a boat!