Photo: Earth lights

Photo courtesy NASA

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NASA’s image of "Earth at Night" is familiar to most Americans. The image appears on posters and postcards, and in most geography textbooks. But how was this image made? And what does it tell us about where and how we live on Earth?

First of all, "Earth at Night" is not a single image, but rather a composite of hundreds of photos taken by low-altitude satellites that are able to detect light emitted by towns, cities, industrial sites, oil fields, and fires. Careful examination of the image reveals much about the distribution of people and their activities on Earth.

Examining the Image

a) Access the "Earth at Night" image online and project the image on a classroom screen, or alternatively, if a computer lab is available, have students working in small groups access the image. Provide students with blank world regional maps and world atlases.

b) Begin by clicking once to zoom in on the United States. (Clicking a second time will return the image to full size.) Have students compare the lights on the image to maps of the U.S. in the atlas in order to identify major urban areas. Have them label these urban areas on a blank map of the U.S., identifying major cities. Ask students to explain the uniform distribution of tiny dots of light in the Plains states (the grid pattern is a remnant of the township and range survey system used to divide land parcels in this area). Ask them to explain the dark areas on the image (dark areas are mountains, desert, or other areas with little or no population).  Have them refer to their atlases to identify and label these areas on their maps.

c) Assign different groups the following regions: South America, Europe, Africa, Southwest Asia, South Asia, East Asia, and Southeast Asia and Oceania. Have them repeat the exercise above for these regions, recording what they observe on the appropriate regional map.

Extending the Activity

Point out to students that not all visible light comes from urban areas. In fact, oil field burn-off flares and fires from slash-and-burn agriculture are also visible.

d) Access an updated version of "Earth at Night" and open the image. Point out the bright yellow and red areas on this image. Have students use maps in their atlases to identify these areas and speculate what the colors represent (yellow areas are oil fields; red areas are agricultural burning).

Each year thousands of schools in the United States participate in the National Geographic Bee using materials prepared by the National Geographic Society. The contest is designed to inspire students to be curious about the world. Schools with students in grades four through eight are eligible for this entertaining and challenging competition.

Registration for the 2015 Geo Bee has ended. Schools can register for next year's Geo Bee in August 2015.

School Geo Bees have all been held. Please mark your calendar for the upcoming State Geo Bee on March 27, 2015, in all 50 states and the District of Columbia. To find out the location of the State Geo Bee for your state, email us at

The national competition of the Geo Bee will be held May 11-13, 2015, at the National Geographic Society’s headquarters in Washington, D.C. It will be televised on May 15, 2015, at 8 p.m. on the National Geographic Channel and NG Wild.

Gain a Global Perspective

The 2014 National Geographic Bee finalists gush about geography.

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    Fund a School

    Donations help fund schools to participate in the National Geographic Bee.

Winners' Video

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    2014 State Winners

    Fifty-four of the nation's brightest young geography whiz kids gathered in Washington, D.C., last spring to take part in the 26th annual National Geographic Bee.

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