Lyot Crater - Revision history

Suitupandshowup at 21:29, 21 April 2020

2020-04-21T21:29:14Z

Suitupandshowup at 21:28, 21 April 2020

2020-04-21T21:28:18Z

Suitupandshowup at 21:26, 21 April 2020

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Suitupandshowup at 21:23, 21 April 2020

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Suitupandshowup: /* See Also */

2020-04-21T21:20:39Z

Suitupandshowup at 21:19, 21 April 2020

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 ESP 045389 2295lyotchannelsbottom.jpg|Close view of channels in Lyot Crater, as seen by HiRISE under HiWish program
 File:Lyot Mars Crater Channel.jpg|Lyot Crater Channel, as seen by [[Mars Reconnaissance Orbiter#CTX (camera)|CTX]].  Water-carved channels have been spotted in Lyot Crater; the curved line may be one.  Click on image for a better view.
 Lyot-impact-site 740.jpg|Lyot crater with elevations exaggerated showing distribution of channels caused by hot ejecta melting ice.
-File:ESP 053485 2305lyotchannel.jpg|Channel
 Image:Lyot Mars Crater Dunes.JPG|Lyot Crater Dunes, as seen by HiRISE.  Click on image to see light-toned deposits and dust devil tracks.

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 Image:Lyot Mars Crater Dunes.JPG|Lyot Crater Dunes, as seen by HiRISE.  Click on image to see light-toned deposits and dust devil tracks.
 File:Lyot Mars Crater Gullies.jpg|Lyot Crater Gullies, as seen by HiRISE.
-File:Lyot Mars Crater Channel.jpg|Lyot Crater Channel, as seen by [[Mars Reconnaissance Orbiter#CTX (camera)|CTX]].  Water-carved channels have been spotted in Lyot Crater; the curved line may be one.  Click on image for a better view.
 </gallery>
 ==References==

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 ESP 045389 2295lyotchannelstop.jpg|Close view of channels in Lyot Crater
 ESP 045389 2295lyotchannelsbottom.jpg|Close view of channels in Lyot Crater, as seen by HiRISE under HiWish program
 Image:Lyot Mars Crater Dunes.JPG|Lyot Crater Dunes, as seen by HiRISE.  Click on image to see light-toned deposits and dust devil tracks.

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 File:ESP 053485 2305lyotchannel.jpg|Channel
 File:Lyot Mars Crater Gullies.jpg|Lyot Crater Gullies, as seen by HiRISE.
 File:Lyot Mars Crater Channel.jpg|Lyot Crater Channel, as seen by [[Mars Reconnaissance Orbiter#CTX (camera)|CTX]].  Water-carved channels have been spotted in Lyot Crater; the curved line may be one.  Click on image for a better view.

← Older revision		Revision as of 21:23, 21 April 2020
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	{{Mars atlas}}		{{Mars atlas}}
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		+	[[File: Wikilyotmola.jpg\|600pxr\|MOLA map of Lyot and other nearby craters. Colors indicate elevations.]]
		+	MOLA map of Lyot and other nearby craters. Colors indicate elevations.
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	Lyot is the deepest crater in Northern Mars		Lyot is the deepest crater in Northern Mars

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 ==See Also==
+*[[Dust devils]]
 *[[High Resolution Imaging Science Experiment (HiRISE)]]
 *[[Rivers on Mars]]
 *[[Martian gullies]]
-*[[Sublimation]]
 *[[Water]]

← Older revision		Revision as of 21:19, 21 April 2020
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	Research published in 2009 describes evidence for liquid water in Lyot in the past.<ref>Dickson \|first1=J. L. \|last2=Fassett \|first2=C. I. \|last3=Head \|first3=J. W. \|title=Amazonian‐aged fluvial valley systems in a climatic microenvironment on Mars: Melting of ice deposits on the interior of Lyot Crater \|journal=Geophysical Research Letters \|date=2009 \|volume=36 \|issue=8 \|doi=10.1029/2009GL037472\|bibcode=2009GeoRL..3608201D}}</ref>		Research published in 2009 describes evidence for liquid water in Lyot in the past.<ref>Dickson \|first1=J. L. \|last2=Fassett \|first2=C. I. \|last3=Head \|first3=J. W. \|title=Amazonian‐aged fluvial valley systems in a climatic microenvironment on Mars: Melting of ice deposits on the interior of Lyot Crater \|journal=Geophysical Research Letters \|date=2009 \|volume=36 \|issue=8 \|doi=10.1029/2009GL037472\|bibcode=2009GeoRL..3608201D}}</ref>
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−	Many channels have been found near Lyot Crater. Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick. Calculations suggest that the ejecta would have had a temperature of at least 250 degrees Fahrenheit. The valleys seem to start from beneath the ejecta near the outer edge of the ejecta. One evidence for this idea is that there are few secondary craters nearby. Few secondary craters were formed because most landed on ice and did not affect the ground below. The ice accumulated in the area when the climate was different. The tilt or [[obliquity]] of the axis changes frequently. During periods of greater tilt, ice from the poles is redistributed to the mid-latitudes. The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean, these features have been dated to the Noachian and [[Hesperian periods—4 to 3 billion years ago.<ref>doi=10.1002/2017GL073821 \| volume=44 \| title=Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation \| journal=Geophysical Research Letters \| pages=5336–5344 \| last1 = Weiss \| first1 = David K.\|</ref> <ref> Weiss \| first1 = D. \| display-authors = etal \| year = 2017 \| title = Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation \| url = \| journal = Geophysical Research Letters \| volume = 44\| issue = \| pages = 5336–5344\| doi = 10.1002/2017GL073821 \|</ref> <ref>http://spaceref.com/mars/hot-rocks-led-to-relatively-recent-water-carved-valleys-on-mars.html</ref>
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	The vast northern plains of Mars are generally flat and smooth with few craters. However, a few large craters do stand out. The giant impact crater, Lyot, is easy to see in the northern part of Ismenius Lacus. There are only a very few craters along the far northern latitudes.<ref>U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991</ref> Lyot Crater is the deepest point in Mars's northern hemisphere.<ref>http://space.com/scienceastronomy/090514--mars-rivers.html</ref> One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and Dust Devil Tracks. Dust devils, which resemble miniature tornados, create tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. It does not take too much fine dust to cover those tracks--experiments in Earth laboratories demonstrate that only a few 10's of microns of dust will do the trick. Note on units: a micron is an older name for micrometre or micrometer. The width of a single human hair ranges from approximately 20 to 200 microns (μm); hence, the dust that can cover dust devil tracks may only be the thickness of a human hair.<ref>https://en.wikipedia.org/wiki/Micrometre</ref> Light-toned materials are an important find because they are widely believed to contain minerals formed in water. Research, published in June 2010, described evidence for liquid water in Lyot crater in the past.		The vast northern plains of Mars are generally flat and smooth with few craters. However, a few large craters do stand out. The giant impact crater, Lyot, is easy to see in the northern part of Ismenius Lacus. There are only a very few craters along the far northern latitudes.<ref>U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991</ref> Lyot Crater is the deepest point in Mars's northern hemisphere.<ref>http://space.com/scienceastronomy/090514--mars-rivers.html</ref> One image below of Lyot Crater Dunes shows a variety of interesting forms: dark dunes, light-toned deposits, and Dust Devil Tracks. Dust devils, which resemble miniature tornados, create tracks by removing a thin, but bright deposit of dust to reveal the darker underlying surface. It does not take too much fine dust to cover those tracks--experiments in Earth laboratories demonstrate that only a few 10's of microns of dust will do the trick. Note on units: a micron is an older name for micrometre or micrometer. The width of a single human hair ranges from approximately 20 to 200 microns (μm); hence, the dust that can cover dust devil tracks may only be the thickness of a human hair.<ref>https://en.wikipedia.org/wiki/Micrometre</ref> Light-toned materials are an important find because they are widely believed to contain minerals formed in water. Research, published in June 2010, described evidence for liquid water in Lyot crater in the past.

← Older revision		Revision as of 20:27, 21 April 2020
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	{{Mars atlas}}		{{Mars atlas}}
	Lyot is the deepest crater in Northern Mars		Lyot is the deepest crater in Northern Mars
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		+	It is located at 50.8° north latitude and 330.7° west longitude within the [[Ismenius Lacus quadrangle]]. It is 236 km in diameter. Lyot Crater is named after Bernard Lyot, a French astronomer (1897–1952).
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		+	Lyot crater, featuring a central peak in the middle, stands out on the flat plains of Vastitas Borealis, which is generally flat and smooth with few large craters.<ref>U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991</ref> <ref>http://space.com/scienceastronomy/090514--mars-rivers.html</ref> West of Lyot is the smaller Micoud crater, and east-southeast is Moreux crater.
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		+	Research published in 2009 describes evidence for liquid water in Lyot in the past.<ref>Dickson \|first1=J. L. \|last2=Fassett \|first2=C. I. \|last3=Head \|first3=J. W. \|title=Amazonian‐aged fluvial valley systems in a climatic microenvironment on Mars: Melting of ice deposits on the interior of Lyot Crater \|journal=Geophysical Research Letters \|date=2009 \|volume=36 \|issue=8 \|doi=10.1029/2009GL037472\|bibcode=2009GeoRL..3608201D}}</ref>
		+
		+	Many channels have been found near Lyot Crater. Research, published in 2017, concluded that the channels were made from water released when the hot ejecta landed on a layer of ice that was 20 to 300 meters thick. Calculations suggest that the ejecta would have had a temperature of at least 250 degrees Fahrenheit. The valleys seem to start from beneath the ejecta near the outer edge of the ejecta. One evidence for this idea is that there are few secondary craters nearby. Few secondary craters were formed because most landed on ice and did not affect the ground below. The ice accumulated in the area when the climate was different. The tilt or [[obliquity]] of the axis changes frequently. During periods of greater tilt, ice from the poles is redistributed to the mid-latitudes. The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean, these features have been dated to the Noachian and [[Hesperian periods—4 to 3 billion years ago.<ref>doi=10.1002/2017GL073821 \| volume=44 \| title=Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation \| journal=Geophysical Research Letters \| pages=5336–5344 \| last1 = Weiss \| first1 = David K.\|</ref> <ref> Weiss \| first1 = D. \| display-authors = etal \| year = 2017 \| title = Extensive Amazonian-aged fluvial channels on Mars: Evaluating the role of Lyot crater in their formation \| url = \| journal = Geophysical Research Letters \| volume = 44\| issue = \| pages = 5336–5344\| doi = 10.1002/2017GL073821 \|</ref> <ref>http://spaceref.com/mars/hot-rocks-led-to-relatively-recent-water-carved-valleys-on-mars.html</ref>
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		+