By: ArtAlienTV-Gigapans
Image: NASA/JPL/University of Arizona
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Uploaded: 16 Nov 2021
Last Updated: 16 Nov 2021
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Many images show that Martian gullies have formed on impact crater walls in both the Northern and Southern hemispheres. Gullies such as the ones shown here have an alcove at the top of the crater wall and channels leading downhill to debris aprons that run out over the crater floor. Some of these gullies show activity today with new material appearing on top of the debris aprons. Many scientists believe that these gullies have been carved by liquid water so this present-day activity is of immense interest. Recently however, an alternate theory has been gaining ground. An analysis of gully activity in craters and on sand dunes shows that activity seems to only occur in the winter at the coldest time of year. The alternate suggestion for gully activity is that accumulations of frost in the gully alcoves starts an avalanche of loose material that does not involve liquid water. This HiRISE image shows gullies on a crater wall in the north polar region. Although it was late summer when we acquired this image, you can see frost within the gully alcoves. These alcoves are on the poleward facing crater wall and so spend much of the time in shadow. This allows the frost to survive. The full-image shows that the opposite (south-facing) wall has similar gullies, but no frost during this season. Scientists are analyzing many images like this in order to try and answer the broader question of whether liquid water is responsible for the these gullies or not. Written by: Shane Byrne (22 September 2010) My enhanced image clips are subject to copyright but the gigapan image is Creative Commons: Attribution. All these finds must be credited to ArtAlienTV unless stated otherwise. TRY the FREE ArtAlienTV APP HERE 👉 http://h.fanapp.mobi/artalientv Access to over 20 million space images. Powerful space research utility app. Please Donate with PAYPAL and help this important research. Send payments to: [email protected] Very much appreciated however small 😊👍