Read satellite images and before-and-after photos
Grade 9 Social Studies Worksheet - Building Confidence
Circle the best answer.
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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.
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
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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.
A reader applies the Landsat key to the Dubai image and calls its red patches rocky debris. What went wrong, Bo asks?
- In both keys red means rocky debris, but Dubai’s image has no ice
- Each image needs its own key; in the ASTER key red means plants
- The ASTER key is wrong and should use the Landsat colors
- Nothing: a Landsat key covers any image taken from space
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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.
Why does a false-color image need a key, Esme asks?
- Colors stand for what the sensor measured; the key says what each means
- 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
- The colors are chosen for looks, so the key explains the picture’s style
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.
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?
- Snow or ice beside open water, above bare rock
- Plants beside open water, above bare rock
- Rocky debris beside open water, above bare rock
- Snow or ice beside plants, above open water
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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.
A glacier is shown in 1986 and 2024. What can Luz compare using the two images?
- The front’s place at the start and at the end
- The reason the front moved, from the colors in the later image
- How fast the front moved in each year, from the gap between the dates
- The front’s place in each year between the two dates
Which pair of images could show how a coastline changed, Milo asks?
- Two images of the same place from the same week, read with one key
- Two images of one place, dated years apart, each read with its own key
- Two images of different places taken on the same date, each read with its own key
- One image of the coast, read with two different keys
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.
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: two keys with the same water color support a rule for other images
- 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: dark blue is the standard water color in false-color images, so no key is needed
The Dubai image shows an island shaped like a palm, red patches and light gray lines. Which reading fits the ASTER key, Pia asks?
- Plants in the red patches, and open water in the gray lines
- 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
- Bare ground in the red patches, and water in the gray lines, as both are common near coasts
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.
What does dark blue tell Ren in Image 1?
- That the surface there is open water
- Whether the water is fresh, since dark blue marks fresh water
- How cold the water is, with darker blue for colder water
- How deep the water is, with darker blue for deeper water
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
- Gray is not used in either key, which has other colors for these features
- 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