Geography of Mars

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High resolution colorized map of Mars based on Viking orbiter images. Surface frost and water ice fog brighten
the impact basin Hellas to the right of lower center; Syrtis Majorjust above it is darkened by winds that sweep
dust off its basaltic surface. Residual north and south polar ice caps are shown at upper and lower right as they
appear in early summer and at minimum size, respectively.

The geography of Mars, also known asareography, entails the delineation and characterization of
regions on Mars. Martian geography is mainly focused on what is calledphysical geography on
Earth; that is the distribution of physical features across Mars and their cartographicrepresentations.
Contents
[hide]

1 History

2 Image map of Mars

3 Topography

3.1 Zero elevation

3.2 Zero meridian

3.3 Martian dichotomy

3.4 Map of quadrangles

4 Nomenclature
o

4.1 Early nomenclature

4.2 Modern nomenclature

5 See also

6 References

7 Further reading

8 External links

History[edit]
Main article: History of Mars observation

Map of Mars by Giovanni Schiaparelli. North is at the top of this map; however, in most maps of Mars drawn
before space exploration the convention amongastronomers was to put south at the top because
the telescopic image of a planet is inverted.

The first observations of Mars were from ground-based telescopes. The history of these
observations are marked by the oppositions of Mars, when the planet is closest to Earth and hence
is most easily visible, which occur every couple of years. Even more notable are the perihelic
oppositions of Mars which occur approximately every 16 years, and are distinguished because Mars
is close to perihelionmaking it even closer to Earth.
In September 1877, (a perihelic opposition of Mars occurred on September
5), Italian astronomer Giovanni Schiaparelli published the first detailed map of Mars. These maps
notably contained features he called canali ("channels"), that were later shown to be an optical
illusion. These canali were supposedly long straight lines on the surface of Mars to which he gave
names of famous rivers on Earth. His term was popularly mistranslated as canals, and so started
the Martian canal controversy.
Following these observations, it was a long held belief that Mars contained vast seas and vegetation.
It was not until spacecraft visited the planet during NASA's Mariner missions in the 1960s that these
myths were dispelled. Some maps of Mars were made using the data from these missions, but it
wasn't until the Mars Global Surveyormission, launched in 1996 and ending in late 2006, that
complete, extremely detailed maps were obtained. These maps are now available online
at http://www.google.com/mars/

Image map of Mars[edit]

The following imagemap of the planet Mars has embedded links to geographical features in addition
to the notedRover and Lander locations. Click on the features and you will be taken to the
corresponding article pages. Northis at the top; Elevations: red (higher), yellow (zero), blue (lower).

Spirit (2004) >

Opportunity (2004) >

< Sojourner (1997)
Viking 1 (1976) >
Viking 2 (1976) >
< Phoenix (2008)
< Mars 3 (1971)

Curiosity (2012) >

< Beagle 2 (2003)

Topography[edit]

High resolution topographic map of Mars based on theMars Global Surveyor laser altimeter research led
by Maria Zuber and David Smith. North is at the top. Notable features include the Tharsis volcanoes in the west
(including Olympus Mons), Valles Marineris to the east of Tharsis, and Hellas basin in the southern
hemisphere.

Mars, 2001, with the southern polar ice cap visible on the bottom.

North Polar region with icecap.

The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast
with the southern highlands, pitted and cratered by ancient impacts. The surface of Mars as seen
from Earth is consequently divided into two kinds of areas, with differing albedo. The paler plains
covered with dust and sand rich in reddish iron oxides were once thought of as Martian 'continents'
and given names like Arabia Terra (land of Arabia) or Amazonis Planitia (Amazonian plain). The dark
features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae
Sinus. The largest dark feature seen from Earth is Syrtis Major Planum.
The shield volcano, Olympus Mons (Mount Olympus), rises 22 km above the surrounding volcanic
plains, and is the highest known mountain on any planet in the solar system. [1] It is in a vast upland
region calledTharsis, which contains several large volcanos. See list of mountains on Mars. The
Tharsis region of Mars also has the solar system's largest canyon system, Valles Marineris or
the Mariner Valley, which is 4,000 km long and 7 km deep. Mars is also scarred by countless impact
craters. The largest of these is the Hellas impact basin. See list of craters on Mars.

Mars has two permanent polar ice caps, the northern one located atPlanum Boreum and the
southern one at Planum Australe.
The difference between Mars' highest and lowest points is nearly 30 km (from the top of Olympus
Mons at an altitude of 21.2 km to the bottom of the Hellas impact basin at an altitude of 8.2 km below
the datum). In comparison, the difference between Earth's highest and lowest points (Mount
Everest and the Mariana Trench) is only 19.7 km. Combined with the planets' different radii, this
means Mars is nearly three times "rougher" than Earth.
The International Astronomical Union's Working Group for Planetary System Nomenclature is
responsible for naming Martian surface features.

Zero elevation[edit]
On Earth, the zero elevation datum is based on sea level. Since Mars has no oceans and hence no
'sea level', it is convenient to define an arbitrary zero-elevation level or "datum" for mapping the
surface. The datum for Mars is arbitrarily defined in terms of a constant atmospheric pressure.
From the Mariner 9 mission up until 2001, this was chosen as 610.5 Pa (6.105 mbar), on the basis
that below this pressure liquid water can never be stable (i.e., the triple point of water is at this
pressure). This value is only 0.6% of the pressure at sea level on Earth. Note that the choice of this
value does not mean that liquid water does exist below this elevation, just that it could were the
temperature to exceed 273.16 K (0 degrees C, 32 degrees F).[1]
In 2001, Mars Orbiter Laser Altimeter data led to a new convention of zero elevation defined as
the equipotential surface (gravitational plus rotational) whose average value at the equator is equal
to the mean radius of the planet.[2]

Zero meridian[edit]
Mars' equator is defined by its rotation, but the location of its Prime Meridian was specified, as was
Earth's, by choice of an arbitrary point which was accepted by later observers. The German
astronomers Wilhelm Beer andJohann Heinrich Mdler selected a small circular feature as a
reference point when they produced the first systematic chart of Mars features in 1830-32. In 1877,
their choice was adopted as the prime meridian by the Italian astronomer Giovanni
Schiaparelli when he began work on his notable maps of Mars. After the spacecraftMariner
9 provided extensive imagery of Mars in 1972, a small crater (later called Airy-0), located in
the Sinus Meridiani ('Middle Bay' or 'Meridian Bay') along the line of Beer and Mdler, was chosen
by Merton Davies of theRAND Corporation to provide a more precise definition of 0.0 longitude
when he established a planetographiccontrol point network.

Martian dichotomy[edit]
Main article: Martian dichotomy
Observers of Martian topography will notice a dichotomy between the northern and southern
hemispheres. Most of the northern hemisphere is flat, with few impact craters, and lies below the
conventional zero elevation level. In contrast, the southern hemisphere is mountains and highlands,
mostly well above zero elevation. The two hemispheres differ in elevation by 1 to 3 km. The border
separating the two areas is very interesting to geologists.
One distinctive feature is the fretted terrain.[3] It contains mesas, knobs, and flat-floored valleys
having walls about a mile high. Around many of the mesas and knobs are lobate debris aprons that
have been shown to be rock-covered glaciers.[4]
Other interesting features are the large river valleys and outflow channels that cut through the
dichotomy.[5][6][7]

Fresh Impact crater on Mars

3.7N 53.4E (November 19, 2013).

Fretted terrain of Ismenius Lacus showing flat floored valleys and cliffs. Photo
taken with Mars Orbiter Camera (MOC) on the Mars Global Surveyor.

Enlargement of the photo on the left showing cliff. Photo taken with high
resolution camera of Mars Global Surveyor (MGS).

View of lobate debris apron along a slope. Image located in Arcadia

quadrangle.

Place where a lobate debris apron begins. Note stripes which indicate
movement. Image located inIsmenius Lacus quadrangle.

The northern lowlands comprise about one-third of the surface of Mars and are relatively flat, with
occasional impact craters. The other two-thirds of the Martian surface are the southern highlands.
The difference in elevation between the hemispheres is dramatic. Because of the density of impact
craters, scientists believe the southern hemisphere to be far older than the northern plains. [8] Much of
heavily cratered southern highlands date back to the period of heavy bombardment, the Noachian.
Multiple hypotheses have been proposed to explain the differences. The three most commonly
accepted are a single mega-impact, multiple impacts, and endogenic processes such as mantle
convection.[9] Both impact-related hypotheses involve processes that could have occurred before the
end of the primordial bombardment, implying that the crustal dichotomy has its origins early in the
history of Mars.
The giant impact hypothesis, originally proposed in the early 1980s, was met with skepticism due to
the impact area's non-radial (elliptical) shape, where a circular pattern would be stronger support for
impact by larger object(s). But a 2008 study[10] provided additional research that supports a single
giant impact. Using geologic data, researchers found support for the single impact of a large object
hitting Mars at approximately a 45-degree angle. Additional evidence analyzing Martian rock
chemistry for post-impact upwelling of mantle material would further support the giant impact theory.

Map of quadrangles[edit]
The following imagemap of the planet Mars is divided into the 30 quadrangles defined by the United
States Geological Survey[11][12] The quadrangles are numbered with the prefix "MC" for "Mars
Chart."[13] Click on the quadrangle and you will be taken to the corresponding article pages. North is
at the top; 0N 180W is at the far left on the equator. The map images were taken by the Mars
Global Surveyor.

0N 180W
0N 0W
90N 0W
MC-01
Mare Boreum

MC-02
Diacria

MC-03
Arcadia

MC-04
Mare Acidalium

MC-05
Ismenius Lacus

MC-06
Casius

MC-07
Cebrenia

MC-08
Amazonis

MC-09
Tharsis

MC-10
Lunae Palus

MC-11
Oxia Palus

MC-12
Arabia

MC-13
Syrtis Major

MC-14
Amenthes

MC-15
Elysium

MC-16
Memnonia

MC-17
Phoenicis

MC-18
Coprates

MC-19
Margaritifer

MC-20
Sabaeus

MC-21
Iapygia

MC-22
Tyrrhenum

MC-23
Aeolis

MC-24
Phaethontis

MC-25
Thaumasia

MC-26
Argyre

MC-27
Noachis

MC-28
Hellas

MC-29

Eridania

MC-30
Mare Australe

Nomenclature[edit]
Early nomenclature[edit]
Although better remembered for mapping the Moon starting in 1830, Johann Heinrich
Mdler and Wilhelm Beerwere the first "areographers". They started off by establishing once and for
all that most of the surface features were permanent, and pinned down Mars' rotation period. In
1840, Mdler combined ten years of observations and drew the first map of Mars ever made. Rather
than giving names to the various markings they mapped, Beer and Mdler simply designated them
with letters; Meridian Bay (Sinus Meridiani) was thus feature "a".
Over the next twenty years or so, as instruments improved and the number of observers also
increased, various Martian features acquired a hodge-podge of names. To give a couple of
examples, Solis Lacus was known as the "Oculus" (the Eye), and Syrtis Major was usually known as
the "Hourglass Sea" or the "Scorpion". In 1858, it was also dubbed the "Atlantic Canale" by the
Jesuit astronomer Angelo Secchi. Secchi commented that it "seems to play the role of the Atlantic
which, on Earth, separates the Old Continent from the New" this was the first time the
fateful canale, which in Italian can mean either "channel" or "canal", had been applied to Mars.
In 1867, Richard Anthony Proctor drew up a map of Mars based, somewhat crudely, on the
Rev. William Rutter Dawes' earlier drawings of 1865, then the best ones available. Proctor explained
his system of nomenclature by saying, "I have applied to the different features the names of those
observers who have studied the physical peculiarities presented by Mars." Here are some of his
names, paired with those later used by Schiaparelli in his Martian map created between 1877 and
1886.[14] Schiaparelli's names were generally adopted and are the names actually used today:

Kaiser Sea = Syrtis Major

Lockyer Land = Hellas Planitia

Main Sea = Lacus Moeris

Herschel II Strait = Sinus Sabaeus

Dawes Continent = Aeria and Arabia

De La Rue Ocean = Mare Erythraeum

Lockyer Sea = Solis Lacus

Dawes Sea = Tithonius Lacus

Madler Continent = Chryse Planitia, Ophir, Tharsis

Maraldi Sea = Maria Sirenum and Cimmerium

Secchi Continent = Memnonia

Hooke Sea = Mare Tyrrhenum

Cassini Land = Ausonia

Herschel I Continent = Zephyria, Aeolis, Aethiopis

Hind Land = Libya

Proctor's nomenclature has often been criticized, mainly because so many of his names honored
English astronomers, but also because he used many names more than once. In
particular, Dawes appeared no fewer than six times (Dawes Ocean, Dawes Continent, Dawes Sea,
Dawes Strait, Dawes Isle, and Dawes Forked Bay). Even so, Proctor's names are not without charm,
and for all their shortcomings they were a foundation on which later astronomers would improve.

Modern nomenclature[edit]
Main article: Planetary nomenclature Mars
Today, names of Martian features derive from a number of sources, but the names of the large
features are derived primarily from the maps of Mars made in 1886 by the Italian
astronomer Giovanni Schiaparelli. Schiaparelli named the larger features of Mars primarily using
names from Greek mythology and to a lesser extent the Bible. Mars Large albedo features retain
many of the older names, but are often updated to reflect new knowledge of the nature of the
features. For example 'Nix Olympica' (the snows of Olympus) has becomeOlympus Mons (Mount
Olympus).
Large Martian craters are named after important scientists and science fiction writers; smaller ones
are named after towns and villages on Earth.
Various landforms studied by the Mars Exploration Rovers are given temporary names or nicknames
to identify them during exploration and investigation. However, it is hoped[attribution needed] that
the International Astronomical Union will make permanent the names of certain major features, such
as the Columbia Hills, which were named after the seven astronauts who died in the Space Shuttle
Columbia disaster.

See also[edit]

Geology of Mars

List of quadrangles on Mars

Martian dichotomy

References[edit]
1.

^ Jump up to:a b Carr, M.H., 2006, The Surface of Mars, Cambridge, 307
p.

2.

Jump up^ Smith, D.; Zuber, M.; Frey, H.; Garvin, J.; Head, J. et al. (25
October 2001). "Mars Orbiter Laser Altimeter: Experiment summary after
the first year of global mapping of Mars". Journal of Geophysical
Research: Planets 106 (E10): 2368923722.doi:10.1029/2000JE001364.

3.

Jump up^ Greeley, R. and J. Guest. 1987. Geological map of the

eastern equatorial region of Mars, scale 1:15,000,000. U. S. Geol. Ser.
Misc. Invest. Map I-802-B, Reston, Virginia

4.

Jump up^ Plaut, J. et al. 2008. Radar Evidence for Ice in lobate debris
aprons in the Mid-Northern Latitudes of Mars. Lunar and Planetary
Science XXXIX. 2290.pdf

5.

Jump up^ Watters, T. et al. 2007. Hemispheres Apart: The Crustal

Dichotomy on Mars. Annual Review Earth Planet Science: 35. 621-652

6.

Jump up^ Irwin III, R. et al. 2004. Sedimentary resurfacing and fretted
terrain development along the crustal dichotomy boundary, Aeolis
Mensae, Mars.: 109. E09011

7.

Jump up^ Tanaka, K. et al. 2003. Resurfacing history of the northern

plains of Mars based on geologic mapping of Mars Global surveyor data.
Journal of Geophysical Research: 108. 8043

8.

Jump up^ Scott, D. and M. Carr. 1978. Geological map of Mars. U.S.
Geol. Surv. Misc. Invest. Map I-803, Reston, Virginia

9.

Jump up^ Watters, T et al. 2007. Hemispheres Apart: The Crustal

Dichotomy on Mars. Annu. Rev. Earth Planet. Sci: 35. 621-652.

10. Jump up^ Jeffrey C. Andrews-Hanna, Maria T. Zuber & W. Bruce

Banerdt The Borealis basin and the origin of the martian crustal
dichotomy Nature 453, 1212-1215 (26 June 2008)
11. Jump up^ Morton, Oliver (2002). Mapping Mars: Science, Imagination,
and the Birth of a World. New York: Picador USA. p. 98. ISBN 0-31224551-3.
12. Jump up^ Online Atlas of Mars
13. Jump up^ Catalog Page for PIA03467
14. Jump up^ Ley, Willy and von Braun, Wernher The Exploration of
Mars New York:1956 The Viking Press Pages 70-71 Schiaparelli's
original map of Mars

Further reading[edit]

External links[edit]

Sheehan, William, "The Planet Mars: A History of Observation and

Discovery" (Full text online) The University of Arizona Press, Tucson.
1996.

Google Mars - Google Maps for Mars, with various surface features
and interesting places pointed out

Mars Maps - Maps of Mars

MEC-1 Prototype

Historical Globes of the Red Planet

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