< ISS020-E-26195 >
| NASA Photo ID | ISS020-E-26195 |
| Focal Length | 800mm |
| Date taken | 2009.07.25 |
| Time taken | 10:57:33 GMT |
Resolutions offered for this image:
1000 x 709 pixels 540 x 383 pixels 720 x 480 pixels 4256 x 2913 pixels 640 x 438 pixels
1000 x 709 pixels 540 x 383 pixels 720 x 480 pixels 4256 x 2913 pixels 640 x 438 pixels
Spacecraft nadir point: 21.5° N, 20.7° E
Photo center point: 19.1° N, 19.2° E
Photo center point by machine learning:
Photo center point: 19.1° N, 19.2° E
Photo center point by machine learning:
Nadir to Photo Center: Southwest
Spacecraft Altitude: 187 nautical miles (346km)
Country or Geographic Name: | CHAD |
Features: | AOROUNGA IMPACT CRATER, YARDANGS |
| Features Found Using Machine Learning: | |
Cloud Cover Percentage: | 10 (1-10)% |
Sun Elevation Angle: | 86° |
Sun Azimuth: | 242° |
Camera: | Nikon D3 Electronic Still Camera |
Focal Length: | 800mm |
Camera Tilt: | 42 degrees |
Format: | 4256E: 4256 x 2832 pixel CMOS sensor, 36.0mm x 23.9mm, total pixels: 12.87 million, Nikon FX format |
Film Exposure: | |
| Additional Information | |
| Width | Height | Annotated | Cropped | Purpose | Links |
|---|---|---|---|---|---|
| 1000 pixels | 709 pixels | No | Yes | Earth From Space collection | Download Image |
| 540 pixels | 383 pixels | Yes | Yes | Earth From Space collection | Download Image |
| 720 pixels | 480 pixels | Yes | Yes | NASA's Earth Observatory web site | Download Image |
| 4256 pixels | 2913 pixels | No | No | Download Image | |
| 640 pixels | 438 pixels | No | No | Download Image |
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No GeoTIFF is available for this photo.Image Caption: Aorounga Impact Crater, Chad
Aorounga Impact Crater is located in the Sahara Desert, in north-central Chad, and is one of the best preserved impact structures in the world. The crater is thought to be middle or upper Devonian to lower Mississippian (approximately 345-370 million years old) based on the age of the sedimentary rocks deformed by the impact. Spaceborne Imaging Radar (SIR) data collected in 1994 suggests that Aorounga is one of a set of three craters formed by the same impact event. The other two suggested impact structures are buried by sand deposits.
The concentric ring structure of the Aorounga crater--renamed Aorounga South in the multiple-crater interpretation of SIR data--is clearly visible in this detailed astronaut photograph. The central highland, or peak, of the crater is surrounded by a small sand-filled trough; this in turn is surrounded by a larger circular trough. Linear rock ridges alternating with light orange sand deposits cross the image from upper left to lower right; these are called yardangs by geomorphologists. Yardangs form by wind erosion of exposed rock layers in a unidirectional wind field. The wind blows from the northeast at Aorounga, and sand dunes formed between the yardangs are actively migrating to the southwest.
Aorounga Impact Crater is located in the Sahara Desert, in north-central Chad, and is one of the best preserved impact structures in the world. The crater is thought to be middle or upper Devonian to lower Mississippian (approximately 345-370 million years old) based on the age of the sedimentary rocks deformed by the impact. Spaceborne Imaging Radar (SIR) data collected in 1994 suggests that Aorounga is one of a set of three craters formed by the same impact event. The other two suggested impact structures are buried by sand deposits.
The concentric ring structure of the Aorounga crater--renamed Aorounga South in the multiple-crater interpretation of SIR data--is clearly visible in this detailed astronaut photograph. The central highland, or peak, of the crater is surrounded by a small sand-filled trough; this in turn is surrounded by a larger circular trough. Linear rock ridges alternating with light orange sand deposits cross the image from upper left to lower right; these are called yardangs by geomorphologists. Yardangs form by wind erosion of exposed rock layers in a unidirectional wind field. The wind blows from the northeast at Aorounga, and sand dunes formed between the yardangs are actively migrating to the southwest.
