Lyot Crater

                       MOLA map of Lyot and other nearby craters.  Colors indicate elevations.

Lyot is the deepest crater in Northern Mars

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).

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. West of Lyot is the smaller Micoud crater, and east-southeast is Moreux crater.

Research published in 2009 describes evidence for liquid water in Lyot 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. Lyot Crater is the deepest point in Mars's northern hemisphere. 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. 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.

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. The existence of these channels is unusual because although Mars used to have water in rivers, lakes, and an ocean; channels in Lyot came after we had thought that Mars had dried up. So Mars had flowing water later then we believed.

Wide view of channels in Lyot Crater, as seen by HiRISE under HiWish program

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  Close view of channels in Lyot Crater

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  Close view of channels in Lyot Crater, as seen by HiRISE under HiWish program

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  Lyot Crater Dunes, as seen by HiRISE. Click on image to see light-toned deposits and dust devil tracks.

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  Channel

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  MOLA map of Lyot and other nearby craters. Colors indicate elevations.

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  Lyot Crater Gullies, as seen by HiRISE.

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  Lyot Crater Channel, as seen by CTX. Water-carved channels have been spotted in Lyot Crater; the curved line may be one. Click on image for a better view.

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  Lyot crater with elevations exaggerated showing distribution of channels caused by hot ejecta melting ice.

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See Also

• Dust devils

• High Resolution Imaging Science Experiment (HiRISE)
• Rivers on Mars
• Martian gullies

• Water