earthglobe.app

Night lights: where people live

From space, the Earth at night is mostly dark, with bright patches where people live. A river in the desert shows up as a thin line of light, and some borders can be seen without any lines drawn on the map. This lesson uses NASA's map of the Earth at night on a 3D globe so students can work out where people live, and why, from the lights alone.

Suggested age: 10–14 · Time: about 35 minutes · Links: all lessons · for schools · about the night map

Learning goals

By the end of the lesson students can:

  1. Explain what the night lights map shows and how it was made.
  2. Use the lights to find cities, coasts, rivers and roads.
  3. Give reasons why some areas are dark, and explain that dark does not always mean empty.
  4. Compare two countries using lights and population figures.

What you need

About the map

The night view is NASA's "Black Marble" map of the Earth at night, as observed in 2016. It was made from data from the Suomi NPP satellite, launched in 2011 by NASA, NOAA and the US Department of Defense. It is not a photo of one night: NASA combined the best cloud-free nights over each part of the world into one image. NASA makes a global night map like this about once a decade, and scientists use the data to estimate how much energy cities use, to get quick information when disasters strike, and to follow the effects of conflict and of people being forced to leave their homes.

Step-by-step globe activity

  1. Guess first (3 min). Ask: "If you could only see the Earth's lights at night, how could you tell where people live?"
  2. Open the night view (3 min). Switch to Night. Turn the globe slowly all the way round. Students call out the brightest places they see.
  3. Find a river in the desert (5 min). Search for Egypt and zoom in. Look for a thin bright line running north through a dark area, widening near the coast. Ask: "What do you think this line is?" (The Nile and its delta.) Tap Egypt to see its population on the card.
  4. Compare neighbours (6 min). Search for South Korea, then look just north of it at North Korea. Ask: "What do you notice?" Tap both countries and compare their populations on the cards. Discuss: if the population difference is much smaller than the difference in light, what else could explain the dark?
  5. Follow a coast (4 min). Turn to the east coast of the United States and follow the band of light from Boston to Washington, D.C. Then find another coast that glows, anywhere in the world.
  6. Find the dark places (6 min). Visit the middle of Australia, Siberia in Russia, the Amazon in Brazil and the Sahara in North Africa. For each one, students suggest why it is dark: desert, forest, ice, mountains, or few people.
  7. Day and night together (4 min). Switch back to Satellite. On the night side of the globe the same city lights appear, more faintly, and the line between day and night follows the real time now. Ask: "Which cities are switching their lights on right now?"
  8. Wrap up (4 min). Students write one sentence: "The night lights map shows … but it cannot show …"

Questions for students

  1. Is the night map a photo taken on one night? How was it made?
  2. What does a thin line of light through a dark desert usually show?
  3. Name two reasons why a large area could be dark at night.
  4. Does dark always mean nobody lives there? Explain.
  5. What can scientists use night lights data for? Give one example.
  6. Lights in the middle of the sea: what could they be?

Answer key (for the teacher)

  1. No. NASA combined many cloud-free nights from 2016, chosen month by month for each land area, into one image.
  2. Towns and farms along a river, where there is water. In Egypt, the lights follow the Nile.
  3. Any two: desert, thick forest, ice sheet, high mountains, ocean, very few people.
  4. No. Some places with many people use less outdoor lighting. The map shows light, not people.
  5. Any one: estimating a city's energy use, getting quick information when a disaster strikes, or following the effects of conflict and of people being forced to move.
  6. Ships, fishing fleets, or oil and gas platforms.

Optional extension

Lights and people. Each pair picks three countries: one very bright, one patchy and one mostly dark. They tap each country and record its population and area from the cards, then work out people per square kilometre (population ÷ area). Does the brightest country also have the most people per square kilometre? What else might explain the difference? For the size of countries without map stretching, continue with how big are countries really?, and for why one side of the globe is dark, see day and night & the seasons.

Frequently asked questions

Is the night view on earthglobe.app live?

No. The city lights come from NASA's Black Marble 2016 map. What is live is the line between day and night in Satellite mode.

Where does the night lights map come from?

From NASA. It was made with data from the Suomi NPP satellite, launched in 2011 by NASA, NOAA and the US Department of Defense.

Why are some countries so much darker than their neighbours?

Light depends on how many people live in a place, but also on how much outdoor lighting they use. A dark area can still have many people.