Read satellite images and before-and-after photos

Grade 9 Social Studies Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Use this

   Card C. Two tiles of one made-up town. Tile 1 uses a Landsat-style key and Tile 2 an ASTER-style key. A large patch beside the river is bright green in Tile 1 and bright red in Tile 2. Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray.

2. 1.

   A patch is bright green in Tile 1 and bright red in Tile 2. What is the patch most likely to be, Ari asks?

   • Two different things, since a patch cannot be green and red in two images at once
   • Plants, since green in a Landsat-style key and red in an ASTER-style key both mean plants
   • Buildings in both tiles, since a bright color marks a built-up area
   • Water in Tile 1 and bare ground in Tile 2, since each key gives its own color

3. Use this

   Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray. Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

4. 2.

   A reader applies the Landsat key to the Dubai image and calls its red patches rocky debris. What went wrong, Bo asks?

   • The ASTER key is wrong and should use the Landsat colors
   • Each image needs its own key; in the ASTER key red means plants
   • In both keys red means rocky debris, but Dubai’s image has no ice
   • Nothing: a Landsat key covers any image taken from space

5. Use this

   Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

6. 3.

   Why does a false-color image need a key, Esme asks?

   • The colors are chosen for looks, so the key explains the picture’s style
   • A key gives the date and place, which are needed to read any image
   • A key gives the picture’s scale, as on a road map
   • Colors stand for what the sensor measured; the key says what each means

7. Use this

   Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray.

8. 4.

   In Image 1, a bright cyan patch lies beside a dark blue patch, above a brown slope. Which reading fits the Landsat key, Jun asks?

   • Rocky debris beside open water, above bare rock
   • Snow or ice beside plants, above open water
   • Snow or ice beside open water, above bare rock
   • Plants beside open water, above bare rock

9. Use this

   Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray. Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

10. 5.

    A student wants an Alaskan glacier as it looked in 1965. Can Landsat help, Kira asks?

    • Yes, but the image would use the ASTER key, since older images do
    • No: a glacier cannot be seen in any image taken from space
    • No: the Landsat program began in 1972, so it has no image from 1965
    • Yes: Landsat is the longest-running series, so it covers the whole century

11. Use this

    Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

12. 6.

    Which pair of images could show how a coastline changed, Milo asks?

    • Two images of different places taken on the same date, each read with its own key
    • Two images of the same place from the same week, read with one key
    • One image of the coast, read with two different keys
    • Two images of one place, dated years apart, each read with its own key

13. Use this

    Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray. Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

14. 7.

    Both keys on Card A use dark blue for water. A student says every false-color image uses dark blue for water. What does Card A support, Noah asks?

    • Yes: dark blue is the standard water color in false-color images, so no key is needed
    • No: the student is wrong, since the two keys do not agree about water
    • That these two keys do; another image may use another color, so check its key
    • Yes: two keys with the same water color support a rule for other images
15. 8.

    The Dubai image shows an island shaped like a palm, red patches and light gray lines. Which reading fits the ASTER key, Pia asks?

    • Red patches are plants; gray lines are buildings or paved surfaces
    • Buildings in the red patches, and plants in the gray lines, as built areas stand out
    • Plants in the red patches, and open water in the gray lines
    • Bare ground in the red patches, and water in the gray lines, as both are common near coasts

16. Use this

    Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray.

17. 9.

    Gray appears in both keys. How do its meanings differ, Tala asks?

    • Gray means buildings in both keys, since gray is the color of concrete
    • Landsat gray is rocky debris on ice; ASTER gray is buildings or paved surfaces
    • Gray means rocky debris in both keys, since both images show rock
    • Gray is not used in either key, which has other colors for these features

18. Use this

    Card A. Two false-color keys (public-domain NASA images, described in words). Image 1 (Landsat, a glacier in Alaska): ice, green slopes, dark water and brown rock around a glacier. Image 2 (ASTER, Dubai, 2011): a coastline with an island shaped like a palm tree, red patches and light gray streets. Landsat key: snow and ice are bright cyan, plants are green, open water is dark blue, bare rock is brown, rocky debris on the ice is gray. ASTER key: plants are red, bare ground is brown, water is dark blue, buildings and paved surfaces are light blue or gray. Card B. Reading rules, in our words. In a false-color image, colors stand for what the sensor measured, so each image needs its own key. Every image has a date. The Landsat program, begun in 1972, is the longest-running series of Earth images from space.

19. 10.

    A third image uses a key that is not on Card A. What should Zee do?

    • Ignore the colors and guess from the shapes alone
    • Use that image’s own key, since Card A’s keys describe only those two images
    • Use the ASTER key, since it is the newer of the two
    • Use the Landsat key, since glaciers are in Alaska and Landsat shows them