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Where is it?Sahara Desert , Chad [ 19.09146866 , 19.23480321 ]
What ’s in the photo?The eye - shaped Aorounga impact structure wall by moving sand sand dune
The Aorounga structure is a roughly 8-mile-wide impact crater left behind by a “city-killer” asteroid that slammed into Earth
Who train the photo?An unnamed astronaut onboard the ISS
When was it taken?Jan . 6 , 2013
This striking spaceman photo shows off an " middle - get " impact volcanic crater in the Sahara Desert . The oculus - like social organisation is surround by migrating sand dunes that are subject of traveling more than 100 feet ( 30 meter ) every year .
The Aorounga structure is surrounded by dark ridges, known as yardangs, that cover this part of the Sahara.
TheAorounga structureis a 7.8 - mile - wide ( 12.6 km ) impingement volcanic crater site in the southeasterly Sahara in northern Chad . The crater is made up of two ring that give the body structure its centre - alike appearance : An inner anchor ring with a central mound , or uplift structure , that look like a pupil ; and an forbidden band that looks like an eyelid . The ring rise around 330 feet ( 100 m ) above the palisade ground but have been heavily eroded over time — similar to other ancient shock crater — and were likely even marvelous and wider primitively .
Experts believe that the structure formed around 345 million years ago and was likely created by a meteor around 2,000 foot ( 600 m ) across , according to estimation from theLunar and Planetary Institute . An impactor of this size , known asa " city - killer whale " asteroid , would have caused widespread damage across the north of Africa and may have even triggered climatical result on a global scale .
The construction also has several dark lines head for the hills across both of its hoop , which are sections of monolithic ridge , known as yardangs , according to theU.S. Geological Survey . These ridges , which can strain up to 100 feet ( 30 m ) above ground stratum , stretch across the surrounding areas for gobs of miles , as you could see in the 2016 astronaut image below .
The 2013 astronaut photo (bottom) helped researchers track how quickly the barchan dunes move by comparing their positions relative to a satellite image from 2003 (top).
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A grouping of five barchan , or " tusk , " Amandine Aurore Lucie Dupin dunes can be see in a whizz - in interlingual rendition of the 2013 picture ( see below ) . Over time , these arrowhead - shaped piles of sand are pushed across the desert by the flatus and move in the diametrical direction that their " horns " are pointed in , accord toNASA ’s Earth Observatory .
By compare their locating in this effigy with satellite images of the same expanse in late 2003 , researchers were able to work out precisely how far they had move in just over nine years . From left to right , the five dunes — labeled 1 , 2 , 3 , 4 and 5 — make a motion by 1,037 feet ( 316 m ) , 902 feet ( 275 m ) , 1,329 substructure ( 405 m ) , 1,043 ft ( 318 m ) , and 1,250 feet ( 381 m ) respectively .
The biggest migrators , 3 and 5 , are also the smallest dune , which is uniform with what we jazz about how these dunes move , according to the Earth Observatory . Dunes smaller than these can be pull asunder within a 10 .
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Barchan dunes have long been known to transmigrate across the Sahara . However , scientists are only just beginning to work out exactly how far they can travel by go after their motion with satellite images . researcher desire these advancements could be used to forecast the grit ’s movements , which could serve extenuate problem get by the dune obstructing roads and asphyxiate agricultural demesne , grant to the Earth Observatory .
Radar picture of the Aorounga anatomical structure accept from space in the late 1990s have also revealed that the center - mould rings could be part of a " crater range . " At least two other smaller volcanic crater were identify on either side of the structure , intimate that smaller office of the Aorounga shooting star broke off from the falling asteroid and bear on the border area , according toThe Planetary Society .
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