Winds of Mars: Aeolian Activity and Landforms


Many modern martian placenames are derived from placenames applied by the early observers of Mars, most notably Schiaparelli, Antoniadi, and Lowell. They mapped albedo features, real and imagined, and gave them fanciful names. Many of these classical terms (marked by "*") were retained even after spacecraft observations revealed their true nature, usually with the addition of a geographical-type designator. Selection of geographical names for all extraterrestrial bodies is the province of the International Astronomical Union (IAU). Two valuable sources for information on martian nomenclature are Blunck (1977) and Masursky et al. (1986).

Aeolian (ay-OH-lee-an) - Pertaining to the wind, from the Latin Aeolius, the God of Wind. Also spelled eolian (ee-OH-lee-an), although I prefer the former, which conforms with both Aeolius and the Aeolian Islands in the Mediterranean.

Albedo (al-BE-doh) - The ratio of radiation reflected from a surface to that impinging on the surface. In digital image processing, 256 gray levels, ranging from pure black (0) to pure white (255), are used to measure the albedo of a surface. From the Latin albus, meaning white.

Arcadia Planitia* (ar-CAY-dee-a plan-EE-sha) - A classical martian placename first used by Schiaparelli in 1882. Arcadia Planitia is located northwest of Tharsis at approximately 50°, 155°. Arkadia is a district in ancient Greece.

Argyre Planitia* (AR-jire plan-EE-sha) - A classical martian placename first used by Schiaparelli in 1877. Argyre Planitia is an 800-km-diameter impact basin located at -50°, 45°. The root word is the Greek argyros meaning silver. Argyre was a mythical island of silver located near present-day Burma.

Barchan (BAR-can) - An isolated, crescent-shaped sand dune. The horns of the crescent point downwind, the direction of migration. From a Turkish word for sand hill, although detailed etymology is unclear.

Chryse Planitia* (CRIS-see plan-EE-sha) - The martian plain upon which VL-1 landed. Chryse is the classical name applied by Schiaparelli in 1877 to an area of high albedo. Chryse was a mythological gold-rich island in the Thailand area, often mentioned along with Argyre.

Dust devil - An atmospheric vortex caused by differential surface heating. Air near the ground is heated by the surface and rises through cooler air aloft. Dust devils pick up fine particles from the surface and thus are made visible. Dust devils on Earth are typically on the order of meters across and are capable of causing minor damage. Martian dust devils are larger.

Erg (erg) - A very large sand mass; a sand sea. From a Hamitic word areg or ergh for such a sand sea in the Sahara.

Hellas Planitia* (HEL-las plan-EE-sha) - A classical martian placename first used by Schiaparelli in 1877. Hellas Planitia is a 2000-km-diameter impact basin located at -40°, 290°. Hellas is an ancient name for Greece and is also a district in ancient Greece.

Hesperia Planum* (hes-PE-ree-a PLAY-num) - Another classical martian placename used by Schiaparelli in 1877, from the Greek Hesperia, meaning Western Land, the ancient Greek name for Italy.

Limb - The edge of a planet from the observer’s vantage point. From the Latin limbus, meaning edge or border.

Mega-barchan - Extremely large, composite, barchan sand dune.

Mons pl. montes - A standard IAU feature name, taken from the Latin mons meaning mountain.

Oxia Palus* (OX-ee-a) - A martian placename that has been retained only as a quadrangle name. Lowell, in 1894, imagined that a canal he named Oxus (from the Oxus River in Uzbekistan, now called the Amu-Darya) passed through this area (15°, 15°), emptying into Oxianus Lacus (Lake of Aral), with an oasis at Oxia Palus. Antoniadi, in 1903, used the term Oxia for a region immediately to the north.

Olympus Mons (o-LIM-pus) - A term derived from a classical martian placename, Nix Olympica (snows of Olympus). Mt. Olympus in northern Greece was the home of the gods in Greek mythology. Olympus Mons is thought to be the largest volcano in the solar system, although some features of greater areal extent and possible volcanic origin occur on Venus. Olympus is visible from Earth under optimum visibility conditions when summit clouds substantially increase the local reflectivity, making Olympus one of the very few classical albedo markings of Mars that turned out to match a real geologic feature.

Palus (PAL-us) - Swamp. A classical name for certain regions on the Moon and Mars, akin to “seas.”

Planitia (plan-EE-sha) - An IAU geographical feature name meaning “low plain.”

Planum (PLAY-num) - An IAU geographical feature name meaning “high plain” or “plateau.”

Sand - Particulate material resulting from rock disintegration, with no connotation as to composition. Sand ranges in diameter from 62.5 micrometers (very fine) to 2 millimeters (very coarse). Martian winds will move 160-micrometer particles more readily than any other size.

Solis Planum* (SOH-liss) - A martian plateau located at 125°, 90°. It retains the name from Solis Lacus (Lake of the Sun), a classical albedo feature from the map of Schiaparelli (1879).

Syria Planum* - A martian plateau located at -15°, 105°, southeast of Tharsis, from a placename applied in 1958 by the IAU to a portion of Thaumasia. Syria is in close proximity to Solis Lacus and Phoencis Lacus (named for the Sun bird); the name was applied to an area near “Sun”-related names because it was used by Homer in the Odyssey to describe an island where the Sun turns about.

Syrtis Major Planitia* (SEER-tiss) - A martian plain located at 10°, 290°, that retains a classical name that was applied by Schiaparelli in 1877. Syrtis is one of the most prominent low albedo features on Mars and is easily seen with a small telescope. The name is derived from the Gulf of Sidra off the Libyan coast, whose shape it superficially resembles.

Tharsis* (THAR-siss) - An elevated region on Mars containing the Tharsis Montes, four extremely large volcanos: Olympus, Ascraeus, Pavonis, and Arsia. Tharsis is a classical martian placename used by Schiaparelli in 1877. It is a name thought to be derived from the Biblical Spanish port of Tartessus, which was destroyed in 500 B.C.

Thaumasia* (thou-MAY-zha) - A classical martian albedo feature named by Schiaparelli in 1879 after Thaumas, god of clouds. It is only used today for the Thaumasia Fossae, fossae meaning long narrow depressions.

Utopia Planitia* - A martian plain located at 40°, 260°. The classical term was applied by Schiaparelli in 1882, using a term for “no where,” an ideal state, coined by Sir Thomas More in 1516.

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