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Can You Tell the Ridges from the Valleys? An Elburz Mountains, Iran story

Mountains
  1. Earthshots
  2. Elburz Mountains, Iran
  3. Can You Tell the Ridges from the Valleys?
Description

Look at the zoomed in images by the coast. Can you tell the peaks (that is, the ridges) from the valleys? It may seem easy, but you may be tricked by a common optical illusion in satellite images called relief inversion.

All Landsat images are designed to be morning views, so all of these images were taken in the morning. The Sun is to the east and south, so these images are lit from below and to the right. This causes the western and northwestern slopes to appear dark because they face the sun less squarely, and so are less illuminated.

However, we unconsciously expect to see images lit from above. This tricks the brain into believing that mountains are valleys or that craters are mountains. If you look at the image upside-down, with the sun angle generally from the top of the image, you will probably see the image differently.

View Related Imagery & Stories

Location

Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north up, image lit from below

Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north up, image lit from below

Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north down, image rotated so it is lit from above

Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north down, image rotated so it is lit from above

Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north up, image lit from below
Aug. 1, 2011, Landsat 5 (path/row 165/35) — Elburz Mountains, Iran; north down, image rotated so it is lit from above

Elburz Mountains, Iran Additional Imagery & Stories

Agriculture
Agriculture

Irrigated agriculture in the valley, shown by the red field patterns, has increased. This agriculture depends on rainfall captured in the mountains an...

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Tehran
Tehran

In the lower right of the main images is Tehran, the capital and largest city in Iran. The plain Tehran lies in is like a bowl. High mountains are to ...

Read More
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