File:Aorounga Impact Crater, Chad.jpg
Identification | |
---|---|
Mission | ISS020 (Expedition 20) |
Roll | E |
Frame | 26195 |
Country or Geographic Name | CHAD |
Features | AOROUNGA IMPACT CRATER, YARDANGS |
Center Point Latitude | 19.1° N |
Center Point Longitude | 19.2° E |
Camera | |
Camera Tilt | 42° |
Camera Focal Length | 800 mm |
Camera | Nikon D3 |
Film | 4256 x 2832 pixel CMOS sensor, 36.0mm x 23.9mm, total pixels: 12.87 million, Nikon FX format. |
Quality | |
Percentage of Cloud Cover | 0-10% |
Nadir What is Nadir? | |
Date | 2009-07-25 |
Time | 10:57:33 |
Nadir Point Latitude | 21.5° N |
Nadir Point Longitude | 20.7° E |
Nadir to Photo Center Direction | Southwest |
Sun Azimuth | 242° |
Spacecraft Altitude | 187 nautical miles (346 km) |
Sun Elevation Angle | 86° |
Orbit Number | 1198 |
Original 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. |
- NASA Expedition 20 crew
- Image Science & Analysis Laboratory, NASA Johnson Space Center
-
Version with alternate grading, corrected vignette and higher resolution
![]() |
This image or video was catalogued by Johnson Space Center of the United States National Aeronautics and Space Administration (NASA) under Photo ID: ISS020-E-026195. This tag does not indicate the copyright status of the attached work. A normal copyright tag is still required. See Commons:Licensing. Other languages:
|
Image acquired with a Nikon D3 digital camera fitted with an 800 mm lens, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Centre.
Licensing
![]() |
This file is in the public domain in the United States because it was solely created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See Template:PD-USGov, NASA copyright policy page or JPL Image Use Policy.) | ![]() |
![]() |
Warnings:
|