{{Short description|Martian dune field}} {{use dmy dates|date=August 2017}} [[File:USGS-Mars-MC-1 Map of Planum Boreum cropped.jpg|thumb|250px|USGS map showing the location of Aspledon Undae in Planum Boreum. The [[prime meridian]] is at the bottom of the map. Aspledon Undae is shown on the southernmost black patch left, between longitude 291.38°E to 301.4°E (43.98°W – 57.08°W).]]

'''Aspledon Undae''' is one of the named northern circumpolar [[dune field]]s in the vicinity of [[Planum Boreum]], the [[Mars|Martian]] North pole. It is named after one of the [[classical albedo features on Mars]].<ref name="USGS">{{cite web|title=Aspledon Undae|url=https://planetarynames.wr.usgs.gov/Feature/14279?__fsk=-155652745|website=Gazetteer of Planetary Nomenclature|publisher=[[USGS]]}}</ref> Its name was officially approved by the [[International Astronomical Union]] (IAU) on 20 March 2007. Its name is [[Greek language|Greek]],<ref name="USGS"/> and derives from the name of a town in [[Boeotia]], [[Ancient Greece]], which, in turn, took its name from Aspledon ({{langx|grc|Ασπληδών}}),<ref name="Greek Myth Index">{{cite web|title=ΑΣΠΛΗΔΩΝ|url=http://www.mythindex.com/greek-mythology/A/Aspledon.html|publisher=Greek Myth Index|access-date=3 September 2017|archive-url=https://web.archive.org/web/20170702071957/http://www.mythindex.com/greek-mythology/A/Aspledon.html|archive-date=2 July 2017|url-status=dead|df=dmy-all}}</ref> son of [[Poseidon]], the ancient Greek god of the sea.<ref>{{cite book|title=Fasti Hellenici: The civil and literary chronology of Greece, from the earliest accounts to the death of Augustus|url=https://books.google.com/books?id=IanLqygofgAC&pg=PA48|year=1834|publisher=at the University Press|page=48|quote=Ασπληδών. Ορχομενού δε υιείς Ασπληδών Κλύμενός τε και Αμφίδοκος θεοειδής, Εustath. ad Ιl. β. p. 272. η Ασπληδών εκλήθη από Ασπληδόνος υιού Ποσειδώνος}}</ref><ref>{{cite book|title=Acta philologorum monacersium auctoritate regia|url=https://books.google.com/books?id=V1k2AQAAMAAJ&pg=PA547|year=1815|publisher=Libraria regia scholarum|page=547|quote=12. ή δε Ασπληδών γράφεται παρ' ετέροις και χωρίς του α. εκλήθη δε από Ασπλη, δόνο, ύιου Ποσειδώνοί, ή Πρεβώνο, ή Ορχομε, νού. Ορχομενού γάρ φασιν υισί.}}</ref><ref name="MartianCartography">{{cite web|title=Classical Albedo Names From Ancient Geography |url=https://ops-alaska.com/publications/2013/2013_MartianCartography_Table01.pdf|website=Proposed Additions to the Cartographic Database of Mars }}</ref> The dunes of Aspledon Undae extend from latitude 71.47°N to 75.14°N and from longitude 305.83°E to 315.04°E (44.96°W – 54.17°W).<ref name="USGS"/> Its centre is located at latitude 73.06°N, longitude 309.65°E (50.35°W), and has a diameter of 215.2&nbsp;km.<ref name="USGS"/>

Aspledon Undae is the southernmost of the albedo-named dune fields of Planum Boreum, and lies to the south of [[Hyperboreae Undae]] and southeast of [[Siton Undae]]. It is theorised that the formation of Aspledon Undae may have occurred during early erosion incidents of the Planum Boreum cavi unit, and that [[Rupes Tenuis]] may have also been a sand source, although it is now depleted. Other dune fields sharing the same formation history include [[Olympia Undae|Olympia]] and [[Siton Undae]].<ref name="Icarus">{{cite journal|author1=Kenneth L. Tanaka, J. Alexis P. Rodriguez, James A. Skinner Jr., Mary C. Bourke, Corey M. Fortezzo, Kenneth E. Herkenhoff, Eric J. Kolb, Chris H. Okubo|title=North polar region of Mars: Advances in stratigraphy, structure, and erosional modification|journal=Icarus|date=28 February 2008|volume=196|issue=2|pages=318–358|doi=10.1016/j.icarus.2008.01.021|url=https://www.researchgate.net/publication/235137809|access-date=25 August 2017|ref=YICAR 8602|bibcode=2008Icar..196..318T}}</ref> Aspledon Undae, along with Hyperboreae, Siton, Olympia, and Alalos Undae is one of the five named northern circumpolar dune fields. However, unlike the other four, it is not one of the densest.<ref name="Tanaka">{{cite journal|author1=K. L. Tanaka, R. K. Hayward|title=MARS' NORTH CIRCUM-POLAR DUNES: DISTRIBUTION, SOURCES, AND MIGRATION HISTORY.|url=http://www.lpi.usra.edu/meetings/dunes2008/pdf/7012.pdf|publisher=Planetary Dunes Workshop: A Record of Climate Change (2008)}}</ref> The dune field of Aspledon Undae, along with those of [[Siton Undae|Siton]], [[Hyperboreae Undae|Hyperboreae]], and [[Abalos Undae]],<ref name="Icarus"/> overlays the lowlands of [[Vastitas Borealis]].<ref name="USGS2">{{cite web|title=Mare Boreum, MC-1 Polar Stereographic Projection Map|url=https://planetarynames.wr.usgs.gov/images/mc1_mola.pdf|publisher=USGS}}</ref> Aspledon Undae has been imaged by [[NASA]]'s [[2001 Mars Odyssey]] robotic spacecraft using the [[Thermal Emission Imaging System]] (THEMIS) camera on board the spacecraft.<ref name="NASA">{{cite web|title=PIA18506: Aspledon Undae|url=https://photojournal.jpl.nasa.gov/catalog/PIA18506|publisher=[[NASA]]}}</ref> {{clear}}

==Formation== [[File:Aspledon Undae.jpg|thumb|250px|Aspledon Undae, a dune field near the Martian north pole. The bottom side of the image shows hundreds of small, isolated dunes. On the top side, these small dunes appear to have coalesced into larger dune forms.]] According to Tanaka et al., [[Planum Boreum]] lies on two major basal units: The Rupes Tenuis unit and the Planum Boreum Cavi unit. The age of the Rupes Tenuis unit is early [[Amazonian (Mars)|Amazonian]], while the Planum Boreum Cavi unit overlays the Rupes Tenuis unit, and its age is Middle to Late Amazonian. The Olympia Undae unit may have formed during early denudation incidents of the Planum Boreum Cavi unit in its immediate neighbourhood.<ref name="Icarus"/> More distant dune fields from the Planum Boreum Cavi unit, such as Siton, Aspledon, and a large portion of [[Olympia Undae]] may have formed during earlier erosional events of the Planum Boreum Cavi unit.<ref name="Icarus"/> Other sources to these dune fields may include [[Rupes Tenuis]], although this source is now considered to be exhausted.<ref name="Icarus"/>

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== See also == * [[Hagal dune field]] * [[Nili Patera dune field]] * [[Ogygis Undae]] {{clear}}

== References == {{reflist|30em}}

{{Geography of Mars}} {{Portal bar|Solar System}}

[[Category:Dunes on Mars]] [[Category:Mare Boreum quadrangle]]