In planetary geology , a ray system comprises radial streaks of fine ejecta thrown out during the formation of an impact crater , looking somewhat like many thin spokes coming from the hub of a wheel. The rays may extend for lengths up to several times the diameter of their originating crater, and are often accompanied by small secondary craters formed by larger chunks of ejecta. Ray systems have been identified on the Moon , Earth ( Kamil Crater ), Mercury , and some moons of the outer planets. Originally it was thought that they existed only on planets or moons lacking an atmosphere , but more recently they have been identified on Mars in infrared images taken from orbit by 2001 Mars Odyssey ' s thermal imager .
12-1044: Comrie may refer to: Places [ edit ] Comrie (crater) , a lunar crater Comrie, Fife , a village in Fife, Scotland Comrie, Perth and Kinross , a village and parish in Strathearn, Scotland People with the surname [ edit ] Aaron Comrie (born 1997), Scottish footballer Adam Comrie (1990–2020), Canadian ice hockey player Bernard Comrie (born 1947), British linguist Elvis Comrie (born 1959), American soccer player Eric Comrie , born 1995), Canadian ice hockey player John Comrie (1875–1939), Scottish physician and medical historian Leroy Comrie , New York City council member Leslie Comrie (1893–1950), New Zealand astronomer Mike Comrie (born 1980), Canadian ice hockey player Neil Comrie (born 1947), Australian police commissioner Paul Comrie (born 1977), Canadian ice hockey player Topics referred to by
24-465: Is different from Wikidata All article disambiguation pages All disambiguation pages Comrie (crater) Comrie is a lunar impact crater situated on the rugged far side of the Moon , beyond the western limb, making it invisible from Earth . It is located in a region surrounded by other notable craters, with Ohm to the south-southwest, Shternberg to the southwest, and Parenago to
36-471: The albedo . Rays can also become covered by lava flows (such as those of Lichtenberg on the moon), or by other impact craters or ejecta. The physical nature of lunar rays has historically been a subject of speculation. Early hypotheses suggested that they were deposits of salt from evaporated water. Later they were thought to be deposits of volcanic ash or streaks of dust. After the impact origin of craters became accepted, Eugene Shoemaker suggested during
48-446: The ray system of the nearby Ohm crater, indicating that debris from Ohm's formation has impacted the area. By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Comrie. Ray system Rays appear at visible, and in some cases infrared wavelengths, when ejecta are made of material with different reflectivity (i.e., albedo ) or thermal properties from
60-409: The 1960s that the rays were the result of fragmented ejecta material. Recent studies suggest that the relative brightness of a lunar ray system is not always a reliable indicator of the age of a ray system. Instead the albedo also depends on the portion of iron oxide (FeO). Low portions of FeO result in brighter materials, so such a ray system can retain its lighter appearance for longer periods. Thus
72-400: The crater, there are several smaller craters. One small crater is near the northwest rim, another slightly southwest of the midpoint, and a third along the surviving section of the southwest rim. The center of the crater features a low central ridge. The eastern half of the interior floor is irregular, but only a few tiny craterlets are present. The crater's western half is marked by streaks from
84-460: The craters Giordano Bruno , Necho , Ohm , Jackson , King , and the small but prominent Pierazzo . Most lateral transport of primary ejecta from impact craters is limited to a distance of a few crater radii, but some larger impacts, such as the impacts that made the Copernicus and Tycho craters, launched primary ejecta halfway around the moon. North Ray and South Ray craters, each with
96-455: The material composition needs to be factored into the albedo analysis to determine age. Among the lunar craters on the near side with pronounced ray systems are Aristarchus , Copernicus , Kepler , Proclus , Dionysius , Glushko , and Tycho . Smaller examples include Censorinus , Stella , and Linné . Similar ray systems also occur on the far side of the Moon, such as the rays radiating from
108-468: The northeast. Comrie is the central member of a unique formation consisting of three connected craters. The northern part of Comrie is attached to a slightly smaller crater, sharing a straight rim between them. The southern portion of Comrie's rim merges with the northern part of a larger, heavily worn crater. This interaction has caused significant erosion, leaving only a portion of Comrie's original rim intact, particularly along its southern extent. Inside
120-404: The relative age of the impact crater, because over time various processes obliterate the rays. On non-atmosphered bodies such as the Moon, space weathering from exposure to cosmic rays and micrometeorites causes a steady reduction of the differential between the ejecta's albedo and that of the underlying material. Micrometeorites in particular produce a glassy melt in the regolith that lowers
132-500: The same term [REDACTED] This disambiguation page lists articles associated with the title Comrie . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Comrie&oldid=1193699283 " Categories : Disambiguation pages Place name disambiguation pages Disambiguation pages with surname-holder lists Hidden categories: Short description
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#1732852579750144-526: The surface on which they are deposited. Typically, visible rays have a higher albedo than the surrounding surface. More rarely an impact will excavate low albedo material, for example basaltic - lava deposits on the lunar maria . Thermal rays, as seen on Mars, are especially apparent at night when slopes and shadows do not influence the infrared energy emitted by the Martian surface. The layering of rays across other surface features can be useful as an indicator of
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