Mead (krater)
| Mead | |
.png) | |
| Himlakropp | Venus |
|---|---|
| Område | Aphrodite Terra |
| Koordinater | 2°24′N 27°00′Ö / 2.40°N 27.00°Ö |
| Diameter | 270 km |
| Djup | 1 km |
| Upptäckare | Magellan |
| Uppkallad efter | Margaret Mead |
Mead är den största nedslagskratern på planeten Venus, 270 kilometer. Mead är en så kallad flerringad krater vars innersta ringberg utgörs av kraterranden. Denna ring omsluter en relativt jämn och plan kraterbotten som döljer ett och annat centralberg.
Kraterbottnen översvämmades vid nedslaget av material som då smälte eller av lava som frigjordes ur planeten under ytan. Detta förklarar varför Mead är så grund; det är bara en nivåskillnad på km mellan kraterranden och kraterbottnen.
Den upptäcktes av rymdsonden Magellan och är upp kallad efter amerikanskan Margaret Mead.
Se även
Källor
- Views of the Solar System - Mead Crater
- ”Mead on Venus” (på engelska). International Astronomical Union. 1 oktober 2006. https://planetarynames.wr.usgs.gov/Feature/3787. Läst 7 december 2021.
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Media som används på denna webbplats
Venus-real color.jpg
Venus in real colors, processed from clear and blue filtered Mariner 10 images.
Venus in real colors, processed from clear and blue filtered Mariner 10 images.
Source images are in the public domain (NASA)
Images processed by Ricardo Nunes, downloaded from http://www.astrosurf.com/nunes/explor/explor_m10.htm
Mead crater (PIA00148).png
(Original caption): This Magellan image mosaic shows the largest (275 kilometers in diameter [170 miles]) impact crater known to exist on Venus at this point in the Magellan mission. The crater is located north of Aphrodite Terra and east of Eistla Regio at latitude 12.5 degrees north and longitude 57.4 degrees east, and was imaged during Magellan orbit 804 on November 12, 1990. The Magellan science team has proposed to name this crater Mead, after Margaret Mead, the American Anthropologist (1901- 1978). All Magellan-based names of features on Venus are, of course, only proposed until final approval is given by the International Astronomical Union-Commission on Planetary Nomenclature. Mead is classified as a multi-ring crater with its innermost, concentric scarp being interpreted as the rim of the original crater cavity. No inner peak-ring of mountain massifs is observed on Mead. The presence of hummocky, radar-bright crater ejecta crossing the radar-dark floor terrace and adjacent outer rim scarp suggests that the floor terrace is probably a giant rotated block that is concentric to, but lies outside of, the original crater cavity. The flat, somewhat brighter inner floor of Mead is interpreted to result from considerable infilling of the original crater cavity by impact melt and/or by volcanic lavas. To the southeast of the crater rim, emplacement of hummocky ejecta appears to have been impeded by the topography of preexisting ridges, thus suggesting a very low ground-hugging mode of deposition for this material. Radar illumination on this and all other Magellan image products is from the left to the right in the scene.
(Original caption): This Magellan image mosaic shows the largest (275 kilometers in diameter [170 miles]) impact crater known to exist on Venus at this point in the Magellan mission. The crater is located north of Aphrodite Terra and east of Eistla Regio at latitude 12.5 degrees north and longitude 57.4 degrees east, and was imaged during Magellan orbit 804 on November 12, 1990. The Magellan science team has proposed to name this crater Mead, after Margaret Mead, the American Anthropologist (1901- 1978). All Magellan-based names of features on Venus are, of course, only proposed until final approval is given by the International Astronomical Union-Commission on Planetary Nomenclature. Mead is classified as a multi-ring crater with its innermost, concentric scarp being interpreted as the rim of the original crater cavity. No inner peak-ring of mountain massifs is observed on Mead. The presence of hummocky, radar-bright crater ejecta crossing the radar-dark floor terrace and adjacent outer rim scarp suggests that the floor terrace is probably a giant rotated block that is concentric to, but lies outside of, the original crater cavity. The flat, somewhat brighter inner floor of Mead is interpreted to result from considerable infilling of the original crater cavity by impact melt and/or by volcanic lavas. To the southeast of the crater rim, emplacement of hummocky ejecta appears to have been impeded by the topography of preexisting ridges, thus suggesting a very low ground-hugging mode of deposition for this material. Radar illumination on this and all other Magellan image products is from the left to the right in the scene.