# Aspledon Undae

**Aspledon Undae** is a dune field on Mars, in the northern lowland plains of [Vastitas Borealis](https://www.edgepedia.org/vastitas-borealis) near the planet's north polar ice cap. It is one of six dune fields on Mars formally classified as an unda (plural undae) by the International Astronomical Union, with a diameter of 215.20 km and its center at 73.06° north latitude, 309.65° east longitude.<sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup><sup> • </sup><sup>[2](https://planetarynames.wr.usgs.gov/SearchResults?Feature+Type=45_Unda&Target=20_Mars)</sup>

| Key fact | Detail |
|---|---|
| Feature type | Unda, undae, the IAU descriptor term for a dune field<sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup> |
| Size | Diameter 215.20 km; center latitude 73.06°, center longitude 309.65° E (planetocentric, +East)<sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup> |
| Approval | Adopted by the IAU on March 20, 2007; origin given as a classical albedo feature name, ethnicity Greek<sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup> |
| Setting | Vastitas Borealis, near the north polar ice cap; mapped in quadrangle MC-1 (Mare Boreum)<sup>[3](https://science.nasa.gov/photojournal/aspledon-undae-false-color/)</sup><sup> • </sup><sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup> |
| Name origin | Aspledon, in Greek myth a son of Poseidon and the nymph Mideia, and a Boeotian city mentioned in Homer's Catalogue of Ships<sup>[4](https://www.researchgate.net/publication/401387531_Encyclopedia_of_Martian_Geography_Volume_1)</sup> |
| Neighboring feature | Aspledon Crater, 18 km across, lies near the dune field<sup>[4](https://www.researchgate.net/publication/401387531_Encyclopedia_of_Martian_Geography_Volume_1)</sup> |
| Imaging | Part of the dune field and a sand-sheet-filled crater were photographed in false color by the THEMIS camera on Mars Odyssey (image PIA24605, added April 23, 2021)<sup>[3](https://science.nasa.gov/photojournal/aspledon-undae-false-color/)</sup> |

## Naming

The name follows the IAU convention for Martian dune fields, which are named after the nearest named albedo feature on the classical Schiaparelli or Antoniadi maps.<sup>[5](https://wenamethestars.inkleby.com/feature/14279)</sup> The parent feature here is the classical albedo feature Aspledon, recorded earlier as Aspledon Lacus at about 64° north, 297° (Lowell 1901; Antoniadi 1929; IAU 1958).<sup>[4](https://www.researchgate.net/publication/401387531_Encyclopedia_of_Martian_Geography_Volume_1)</sup> In Greek mythology and ancient geography, Aspledon was a son of [Poseidon](https://www.edgepedia.org/poseidon) and the nymph Mideia, and also a city of Boeotia near modern Pirgos, mentioned by [Homer](https://www.edgepedia.org/homer) in the Catalogue of Ships of the *Iliad*; a related tradition makes Aspledon a lake in Boeotia, formed by the floods of the river Cephissus south of Orchomenos.<sup>[4](https://www.researchgate.net/publication/401387531_Encyclopedia_of_Martian_Geography_Volume_1)</sup>

The descriptor term unda comes from the Latin for water waves and is used to mean undulatory in planetary nomenclature; all dune fields outside Earth are called unda or undae.<sup>[6](https://themis.asu.edu/zoom-20180314a)</sup>

## Location and setting

The Gazetteer of Planetary Nomenclature places the feature between 71.47° and 75.14° north latitude and 305.83° to 315.04° east longitude in the planetocentric, east-positive coordinate system, equivalent to about 44.96° to 54.17° west longitude; it falls in the MC-1 (Mare Boreum) quadrangle.<sup>[1](https://planetarynames.wr.usgs.gov/Feature/14279)</sup> NASA describes the dune field as lying in Vastitas Borealis, near the north polar ice cap.<sup>[3](https://science.nasa.gov/photojournal/aspledon-undae-false-color/)</sup>

## Relation to the north polar dune fields

Aspledon Undae is one of six named undae on Mars. Five of them ring the north polar cap: [Abalos Undae](https://www.edgepedia.org/abalos-undae) (442.74 km across), [Hyperboreae Undae](https://www.edgepedia.org/hyperboreae-undae) (463.65 km), [Olympia Undae](https://www.edgepedia.org/olympia-undae) (1507.96 km, the largest continuous dune field on Mars), Siton Undae (222.97 km), and Aspledon Undae itself; Ogygis Undae (87.70 km) lies in the southern hemisphere.<sup>[2](https://planetarynames.wr.usgs.gov/SearchResults?Feature+Type=45_Unda&Target=20_Mars)</sup><sup> • </sup><sup>[6](https://themis.asu.edu/zoom-20180314a)</sup> Aspledon Undae and Siton Undae were both approved on the same date, March 20, 2007, while Abalos and Hyperboreae Undae date from 1988 and Olympia Undae from 2003.<sup>[2](https://planetarynames.wr.usgs.gov/SearchResults?Feature+Type=45_Unda&Target=20_Mars)</sup>

## Observation

The region has been mapped by NASA's Mars Odyssey orbiter through its Thermal Emission Imaging System (THEMIS). A false-color THEMIS VIS image released on April 23, 2021 shows part of the dune field together with a crater filled by a large sand sheet; the image was captured on May 8, 2019 at latitude 71.2167, longitude 309.213. False-color combinations of the camera's five filters can reveal subtle surface variations not visible in a single band.<sup>[3](https://science.nasa.gov/photojournal/aspledon-undae-false-color/)</sup>

## References

1. [Aspledon Undae, Gazetteer of Planetary Nomenclature, USGS Astrogeology Science Center](https://planetarynames.wr.usgs.gov/Feature/14279)
2. [Nomenclature Search Results, Feature Type Unda, Target Mars, Gazetteer of Planetary Nomenclature](https://planetarynames.wr.usgs.gov/SearchResults?Feature+Type=45_Unda&Target=20_Mars)
3. [Aspledon Undae – False Color, NASA Science Photojournal](https://science.nasa.gov/photojournal/aspledon-undae-false-color/)
4. [Encyclopedia of Martian Geography, Volume 1](https://www.researchgate.net/publication/401387531_Encyclopedia_of_Martian_Geography_Volume_1)
5. [Aspledon Undae (Mars), We Name The Stars (Inkleby)](https://wenamethestars.inkleby.com/feature/14279)
6. [Investigating Mars: Olympia Undae, Mars Odyssey Mission THEMIS, Arizona State University](https://themis.asu.edu/zoom-20180314a)

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*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Planetary surfaces and named features › Martian surface features › Martian regions and terrain › Martian plains, terrae, and polar regions › Northern lowlands planitiae*

*Initially written Oct 21, 2026 · Edited: Oct 25, 2026*

*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*

License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license