Mars
Mars as seen by the Hubble Space Telescope
Epoch J2000
Aphelion249,209,300 km
1. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 665861 AU
Perihelion206,669,000 km
1. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 381497 AU
Semi-major axis227,939,100 km
1. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 523679 AU
Eccentricity0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 093315
Orbital period686. The orbital period is the time taken for a given object to make one complete Orbit about another object 971 day

1. 8808 Julian years

668. In Astronomy, a Julian year (symbol a) is a unit of measurement of Time defined 5991 sols
Synodic period779. Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars The orbital period is the time taken for a given object to make one complete Orbit about another object 96 day
2. 135 Julian years
Average orbital speed24. The orbital speed of a body generally a Planet, a Natural satellite, an artificial satellite, or a Multiple star, is the speed at which it 077 km/s
Inclination1. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 850°
5. 65° to Sun's Equator
Longitude of ascending node49. The Sun (Sol is the Star at the center of the Solar System. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the The longitude of the ascending node (☊ or Ω is one of the Orbital elements used to specify the Orbit of an object in space 562°
Argument of perihelion286. The argument of periapsis (or argument of perifocus) ( ω) is the Orbital element describing the Angle of an Orbiting body's periapsis 537°
Satellites2
Physical characteristics
Equatorial radius3,396. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the 2 ± 0. 1 km[a][2]
0. 533 Earths
Polar radius3,376. A geographical pole, or geographic pole, is either of two fixed points on the surface of a spinning body or Planet, at 90 degrees from the Equator, based 2 ± 0. 1 km[a][2]
0. 531 Earths
Flattening0. Ellipticity redirects here For the mathematical topic of ellipticity see Elliptic operator. 00589 ± 0. 00015
Surface area144,798,500 km²
0. Equation A spheroid centered at the origin and rotated about the z axis is defined by the implicit equation \left(\frac{x}{a}\right^2+\left(\frac{y}{a}\right^2+\left(\frac{z}{b}\right^2 284 Earths
Volume1. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically 6318×1011 km³
0. 151 Earths
Mass6. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object 4185×1023 kg
0. 107 Earths
Mean density3. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 934 g/cm³
Equatorial surface gravity3. The surface gravity, g, of an astronomical or other object is the Gravitational acceleration experienced at its surface 69 m/s²
0. 376 g
Escape velocity5. g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s In Physics, escape velocity is the speed where the Kinetic energy of an object is equal to the magnitude of its Gravitational potential energy 027 km/s
Sidereal rotation
period
1. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars 025957 day
24. 62296 h
Equatorial rotation velocity868. 22 km/h
Axial tilt25. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. 19°
North pole right ascension21 h 10 min 44 s
317. Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 68143°
North pole declination52. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either 88650°
Albedo0. The albedo of an object is the extent to which it diffusely reflects light from the sun 15
Surface temp.
Kelvin
Celsius
minmeanmax
186 K227 K268 K[4]
−87 °C−46 °C−5 °C
Apparent magnitude+1. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The Celsius Temperature scale was previously known as the centigrade scale. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 8 to -2. 91[3]
Angular diameter3. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 5" — 25. 1"[3]
Atmosphere
Surface pressure0. As an adjective the term "martian" is used to describe anything pertaining to the Planet Mars. 7–0. 9 kPa
Composition95. 72% Carbon dioxide

2. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single 7% Nitrogen
1. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 6% Argon
0. This article pertains to the chemical element For other uses see Argon (disambiguation. 2% Oxygen
0. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 07% Carbon monoxide
0. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. 03% Water vapor
0. Water is a common Chemical substance that is essential for the survival of all known forms of Life. 01% Nitric oxide
2. Nitric oxide or nitrogen monoxide is a Chemical compound with Chemical formula N[[Oxygen O]] 5 ppm Neon
300 ppb Krypton
130 ppb Formaldehyde
80 ppb Xenon
30 ppb Ozone

10 ppb Methane

Mars (pronounced [ˈmɑːz] (in British English) or [ˈmɑːrz] (in American English) ) is the fourth planet from the Sun in the Solar System. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Krypton (ˈkrɪptən or /ˈkrɪptɒn/ from kryptos "hidden" is a Chemical element with the symbol Kr and Atomic number 36 "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Xenon (ˈzɛnɒn or) is a Chemical element represented by the symbol Xe. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly OZONE is an object oriented Operating system written in the C programming language. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The Sun (Sol is the Star at the center of the Solar System. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. The planet is named after Mars, the Roman god of war. Mars was the Roman Warrior god, the son of Juno and Jupiter, husband of Bellona, and the lover of Venus. Roman mythology, or more appropriately Latin mythology, refers to the mythological beliefs of the Italic people inhabiting the region of Latium and its "War Gods" redirects here For the video game see War Gods (video game. It is also referred to as the "Red Planet" because of its reddish appearance as seen from Earth. The apparent color of the Martian surface enabled humans to distinguish it from other planets early in human history and motivated them to weave fables of war in association EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. A terrestrial planet, telluric planet or rocky planet is a Planet that is primarily composed of Silicate rocks Within our An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body Plate tectonics and hotspots Divergent plate boundaries At the In Geology, a valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is A desert is a Landscape or region that receives very little precipitation. A polar ice cap is a high- Latitude region of a Planet or moon that is covered in Ice. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System. A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak Valles Marineris ( Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter In addition to its geographical features, Mars’ rotational period and seasonal cycles are likewise similar to those of Earth. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather.

Mars is currently host to three functional orbiting spacecraft: Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter. A spacecraft is a Vehicle or machine designed for Spaceflight. 2001 Mars Odyssey is a Robotic spacecraft Orbiting the planet Mars. Mars Express is a Space exploration mission being conducted by the European Space Agency (ESA NASA 's Mars Reconnaissance Orbiter ( MRO) is a multipurpose Spacecraft designed to conduct Reconnaissance and exploration of Mars This is more than any planet in the Solar System except Earth. The surface is also home to the two Mars Exploration Rovers (Spirit and Opportunity), the lander Phoenix, and several inert landers and rovers that either failed or completed missions. NASA 's Mars Exploration Rover ( MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of MER-A ( Mars Exploration Rover - A) known as Spirit, is the first of the two rovers of NASA 's Mars Exploration Rover MER-B ( Mars Exploration Rover - B) known as Opportunity, is the second of the two rovers of NASA 's Mars Exploration A lander is a Spacecraft which descends toward and comes to rest on the surface of an Astronomical body. Phoenix is a Robotic spacecraft on a Space exploration mission on Mars under the Mars Scout Program. Geological evidence gathered by these and preceding missions suggests that Mars previously had large-scale water coverage, while observations also indicate that small geyser-like water flows have occurred in recent years. A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase [5] Observations by NASA's Mars Global Surveyor show evidence that parts of the southern polar ice cap have been receding. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program [6]

Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. TemplateInfobox Planet.--> Deimos (ˈdaɪməs; also /ˈdiːməs/ These may be captured asteroids, similar to 5261 Eureka, a Martian Trojan asteroid. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but TemplateInfobox Planet. --> 5261 Eureka (jʊˈriːkə was discovered at Mt Palomar on June 20 Mars can be seen from Earth with the naked eye. Its apparent magnitude reaches −2. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 9,[3] a brightness surpassed only by Venus, the Moon, and the Sun, though most of the time Jupiter will appear brighter to the naked eye than Mars. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University

Physical characteristics

Size comparison of terrestrial planets (left to right): Mercury, Venus, Earth, and Mars. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

Mars has approximately half the radius of Earth and only one-tenth the mass, being less dense, but its surface area is only slightly less than the total area of Earth's dry land. Remote Authentication Dial In User Service ( RADIUS) is a networking protocol that provides centralized access authorization and accounting management for people or computers Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object Surface area is the measure of how much exposed Area an object has [3] While Mars is larger and more massive than Mercury, Mercury has a higher density. This results in a slightly stronger gravitational force at Mercury's surface. The red-orange appearance of the Martian surface is caused by iron(III) oxide, more commonly known as hematite, or rust. Iron(III oxide —also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply Rust —is [7]

Geology

Main article: Geology of Mars

Based on orbital observations and the examination of the Martian meteorite collection, the surface of Mars appears to be composed primarily of basalt. The geology of Mars, also known as areology (from Greek grc Ἂρης Arēs, " Ares " and grc -λογία -logia A Mars meteorite is a Meteorite that has landed on Earth and originated from Mars. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Some evidence suggests that a portion of the Martian surface is more silica-rich than typical basalt, and may be similar to andesitic rocks on Earth; however, these observations may also be explained by silica glass. For the extinct cephalopod genus see Andesites. Andesite (ˈændəsaɪt is an igneous, Volcanic rock, of intermediate Much of the surface is deeply covered by a fine iron(III) oxide dust that has the consistency of talcum powder. Iron(III oxide —also known as ferric oxide, Hematite, red iron oxide, synthetic maghemite, colcothar, or simply Rust —is Baby powder is an Astringent powder used for preventing rashes on the area covered by a Diaper (see Diaper rash)

Rock strewn surface imaged by Mars Pathfinder

Although Mars has no intrinsic magnetic field, observations show that parts of the planet's crust have been magnetized and that alternating polarity reversals of its dipole field have occurred. The Mars Pathfinder was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor This paleomagnetism of magnetically susceptible minerals has properties that are very similar to the alternating bands found on the ocean floors of Earth. Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various Magnetic Minerals through time Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere One theory, published in 1999 and re-examined in October 2005 (with the help of the Mars Global Surveyor), is that these bands demonstrate plate tectonics on Mars 4 billion years ago, before the planetary dynamo ceased to function and caused the planet's magnetic field to fade away. The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere The dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a Magnetic field. [8]

Current models of the planet's interior imply a core region about 1,480 kilometres in radius, consisting primarily of iron with about 14–17% sulfur. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 This iron sulfide core is partially fluid, and has twice the concentration of the lighter elements than exist at Earth's core. Iron(II sulfide is a Chemical compound with the formula FeS In practice iron sulfides are often Non-stoichiometric. The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but now appears to be inactive. The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided The average thickness of the planet's crust is about 50 km, with a maximum thickness of 125 km. [9] Earth's crust, averaging 40 km, is only a third as thick as Mars’ crust relative to the sizes of the two planets.

The geological history of Mars can be split into many epochs, but the following are the three main ones:

• Noachian epoch (named after Noachis Terra): Formation of the oldest extant surfaces of Mars, 3. Noachis Terra (lit "Land of Noah " is an extensive southern Landmass ( terra) of the Planet Mars. 8 billion years ago to 3. 5 billion years ago. Noachian age surfaces are scarred by many large impact craters. The Tharsis bulge volcanic upland is thought to have formed during this period, with extensive flooding by liquid water late in the epoch. The Tharsis region on Mars is an enormous Volcanic plateau located on Mars' equator at the western end of Valles Marineris.
• Hesperian epoch (named after Hesperia Planum): 3. 5 billion years ago to 1. 8 billion years ago. The Hesperian epoch is marked by the formation of extensive lava plains.
• Amazonian epoch (named after Amazonis Planitia): 1. Amazonis Planitia is one of the smoothest plains on Mars. It is located between the Tharsis and Elysium volcanic provinces to the west of 8 billion years ago to present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Olympus Mons formed during this period along with lava flows elsewhere on Mars. Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System.

A major geological event occurred on Mars on February 19, 2008, and was caught on camera by the Mars Reconnaissance Orbiter. Events 197 - Roman Emperor Septimius Severus defeats usurper Clodius Albinus in the Battle of Lugdunum 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common NASA 's Mars Reconnaissance Orbiter ( MRO) is a multipurpose Spacecraft designed to conduct Reconnaissance and exploration of Mars Images capturing a spectacular avalanche of materials thought to be fine grained ice, dust, and large blocks are shown to have detached from a 2,300-foot (701 m) high cliff. Evidence of the avalanche is present in the dust clouds left above the cliff afterwards. [10]

Hydrology

Photo of microscopic rock forms indicating past signs of water, taken by Opportunity

Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods[11][12] but water ice is in no short supply, with two polar ice caps made largely of ice. MER-B ( Mars Exploration Rover - B) known as Opportunity, is the second of the two rovers of NASA 's Mars Exploration [13] In March 2007, NASA announced that the volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 metres. [14] Additionally, an ice permafrost mantle stretches down from the pole to latitudes of about 60°. This article is about frozen ground For other meanings see Permafrost (disambiguation. [13]

Much larger quantities of water are thought to be trapped underneath Mars's thick cryosphere, only to be released when the crust is cracked through volcanic action. The evolution of H2O on either planet needs be understood in the context of the other terrestrial planetary bodies and their current H2O inventories The cryosphere, derived from the Greek word kryo for " Cold " or "too cold" is the term which collectively describes the portions of The largest such release of liquid water is thought to have occurred when the Valles Marineris formed early in Mars's history, enough water being released to form the massive outflow channels. Valles Marineris ( Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter There are two major classes of channel on Mars: The large valley networks which generally formed early in the history of the planet and The outflow channels which formed A smaller but more recent event of the same kind may have occurred when the Cerberus Fossae chasm opened about 5 million years ago, leaving a supposed sea of frozen ice still visible today on the Elysium Planitia centered at Cerberus Palus. The Cerberus Fossae are a series of semi-parallel fissures on Mars formed by faults which pulled the crust apart in the Cerberus region (9°N 197°W The word million In standard English, the -lli- in million is pronounced with an l-sound followed by a Elysium Planitia is the second largest volcanic region on Mars, after Tharsis Montes. [15] However, the morphology of this region is more consistent with the ponding of lava flows causing a superficial similarity to ice flows. [16] These lava flows probably draped the terrain established by earlier catastrophic floods of Athabasca Valles. [17] Significantly rough surface texture at decimeter (dm) scales, thermal inertia comparable to that of the Gusev plains, and hydrovolcanic cones are consistent with the lava flow hypothesis. [17] Furthermore, the stoichiometric mass fraction of H2O in this area to tens of centimeter depths is only ~4%,[18] easily attributable to hydrated minerals[19] and inconsistent with the presence of near-surface ice.

More recently the high resolution Mars Orbiter Camera on the Mars Global Surveyor has taken pictures which give much more detail about the history of liquid water on the surface of Mars. The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched Despite the many giant flood channels and associated tree-like network of tributaries found on Mars there are no smaller scale structures that would indicate the origin of the flood waters. It has been suggested that weathering processes have denuded these, indicating the river valleys are old features. Higher resolution observations from spacecraft like Mars Global Surveyor also revealed at least a few hundred features along crater and canyon walls that appear similar to terrestrial seepage gullies. The gullies tend to be in the highlands of the southern hemisphere and to face the Equator; all are poleward of 30° latitude. [20] The researchers found no partially degraded (i. e. weathered) gullies and no superimposed impact craters, indicating that these are very young features.

Changing gully deposits on Mars

In a particularly striking example (see image) two photographs, taken six years apart, show a gully on Mars with what appears to be new deposits of sediment. Michael Meyer, the lead scientist for NASA's Mars Exploration Program, argues that only the flow of material with a high liquid water content could produce such a debris pattern and colouring. Whether the water results from precipitation, underground or another source remains an open question. [21] However, alternative scenarios have been suggested, including the possibility of the deposits being caused by carbon dioxide frost or by the movement of dust on the Martian surface. [22][23]

Further evidence that liquid water once existed on the surface of Mars comes from the detection of specific minerals such as hematite and goethite, both of which sometimes form in the presence of water. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of Hematite, also spelt hæmatite, is the Mineral form of Iron(III oxide (Fe2O3 one of several Iron oxides Goethite, named after the German Polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low temperature environments [24]

Nevertheless, some of the evidence believed to indicate ancient water basins and flows has been negated by higher resolution studies taken at resolution about 30 cm by the Mars Reconnaissance Orbiter. [25]

Geography

This approximate true-color image, taken by the Mars Exploration Rover Opportunity, shows the view of Victoria Crater from Cape Verde. The "geography" of Mars, also known as areography, entails the delineation and characterization of regions on Mars. This is a list of all named mountains on Mars. Mons refers to a large isolated mountain There are hundreds of thousands of craters on Mars, but only some of them have names MER-B ( Mars Exploration Rover - B) known as Opportunity, is the second of the two rovers of NASA 's Mars Exploration Victoria Crater is an Impact crater located at 550°W 205°S in Meridiani Planum, on Mars, currently being visited by the Mars Exploration It was captured over a three-week period, from October 16 - November 6, 2006.

Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer were the first "areographers". Johann Heinrich von Mädler ( May 29 1794 &ndash March 14 1874) was a German Astronomer. Wilhelm Wolff Beer ( 4 January 1797 &ndash 27 March 1850) was a Banker and Astronomer from Berlin, They began by establishing once and for all that most of Mars’ surface features were permanent, and determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars. Rather than giving names to the various markings, Beer and Mädler simply designated them with letters; Meridian Bay (Sinus Meridiani) was thus feature "a. "[26]

Today, features on Mars are named from a number of sources. Large albedo features retain many of the older names, but are often updated to reflect new knowledge of the nature of the features. The albedo of an object is the extent to which it diffusely reflects light from the sun For example, Nix Olympica (the snows of Olympus) has become Olympus Mons (Mount Olympus). [27]

Mars’ equator is defined by its rotation, but the location of its Prime Meridian was specified, as was Earth's (at Greenwich), by choice of an arbitrary point; Mädler and Beer selected a line in 1830 for their first maps of Mars. The Prime Meridian is the meridian (line of Longitude) at which longitude is defined to be 0° Greenwich ( ˈɡrɛnɪtʃ GREN-itch /ˈɡrɛnɪdʒ/ GREN-idge or /ˈɡrɪnɪdʒ/ GRIN-idge is a district in south-east London, After the spacecraft Mariner 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"), was chosen for the definition of 0. Mariner 9 (Mariner Mars '71 / Mariner-I was a NASA space probe orbiter that helped in the exploration of Mars and was part of the Mariner program. Airy-0 is a crater on Mars whose location defines the position of the Prime meridian of that planet Sinus Meridiani is a feature name for an Albedo feature on Mars stretching east-west just south of that planet's Equator. 0° longitude to coincide with the original selection.

Since Mars has no oceans and hence no 'sea level', a zero-elevation surface or mean gravity surface also had to be selected. Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System. Zero-elevation surface is a widely-accepted vertical reference point that is used to describe a surface such as that of a Planet. Zero altitude is defined by the height at which there is 610. 5 Pa (6. 105 mbar) of atmospheric pressure. This pressure corresponds to the triple point of water, and is about 0. In Thermodynamics, the triple point of a substance is the Temperature and Pressure at which three phases (for example Gas, Liquid 6% of the sea level surface pressure on Earth. [28]

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 thus 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). Arabia Terra is a large upland region in the north of Mars. It is densely cratered and heavily eroded Amazonis Planitia is one of the smoothest plains on Mars. It is located between the Tharsis and Elysium volcanic provinces to the west of The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus. Mare Erythraeum is a very large dark dusky region of Mars that can be viewed by even a small Telescope. Aurorae Sinus is a dark feature in the southern hemisphere of the Planet Mars. The largest dark feature seen from Earth is Syrtis Major. Syrtis Major Planum is a "dark spot" (an Albedo feature) located in the boundary between the northern lowlands and southern highlands of Mars. [29]

The shield volcano, Olympus Mons (Mount Olympus), at 26 km is the highest known mountain in the Solar System. A shield volcano is a large Volcano with shallow-sloping sides Olympus Mons ( Latin for "Mount Olympus" is the highest known Volcano and Mountain in the Solar System. It is an extinct volcano in the vast upland region Tharsis, which contains several other large volcanoes. The Tharsis region on Mars is an enormous Volcanic plateau located on Mars' equator at the western end of Valles Marineris. It is over three times the height of Mount Everest which in comparison stands at only 8. Mount Everest, also called Sagarmatha (सगरमाथा meaning Head of the Sky) or Chomolungma, Qomolangma or Zhumulangma (in 848 km.

Mars is also scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 km or greater have been found. In the broadest sense the term impact crater can be applied to any depression natural or manmade resulting from the high velocity impact of a projectile with larger body [30] The largest of these is the Hellas impact basin, a light albedo feature clearly visible from Earth. False color of Hellas Planitiajpeg|thumb|220px|This elevation map shows the surrounding elevated debris ring]] Hellas Planitia, also known as the Hellas Impact Basin An albedo feature is a large area on the surface of a Planet (or other Solar system body which shows a contrast in brightness or darkness ( Albedo) with [31] Due to the smaller mass of Mars, the probability of an object colliding with the planet is about half that of the Earth. However, Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is also more likely to be struck by short-period comets, i. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — e. , those that lie within the orbit of Jupiter. [32] In spite of this, there are far fewer craters on Mars compared with the Moon because Mars's atmosphere provides protection against small meteors. Some craters have a morphology that suggests the ground was wet when the meteor impacted.

The large canyon, Valles Marineris (Latin for Mariner Valleys, also known as Agathadaemon in the old canal maps), has a length of 4000 km and a depth of up to 7 km. Valles Marineris ( Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes The length of Valles Marineris is equivalent to the length of Europe and extends across one-fifth the circumference of Mars. By comparison, the Grand Canyon on Earth is only 446 km long and nearly 2 km deep. The Grand Canyon Valles Marineris was formed due to the swelling of the Tharis area which caused the crust in the area of Valles Marineris to collapse. Another large canyon is Ma'adim Vallis (Ma'adim is Hebrew for Mars). Ma'adim Vallis is one of the largest Canyons on Mars, about 700 km long and significantly larger than Earth's Grand Canyon. It is 700 km long and again much bigger than the Grand Canyon with a width of 20 km and a depth of 2 km in some places. It is possible that Ma'adim Vallis was flooded with liquid water in the past. [33]

THEMIS image of cave entrances on Mars

Images from the Thermal Emission Imaging System (THEMIS) aboard NASA's Mars Odyssey orbiter have revealed seven possible cave entrances on the flanks of the Arsia Mons volcano. The Thermal Emission Imaging System ( THEMIS) is a camera on board the 2001 Mars Odyssey orbiter 2001 Mars Odyssey is a Robotic spacecraft Orbiting the planet Mars. A cave is a natural underground void large enough for a human to enter Arsia Mons is the southernmost of three Volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the Equator of the Planet [34] The caves, named Dena, Chloe, Wendy, Annie, Abbey, Nikki and Jeanne after loved ones of their discoverers, are collectively known as the "seven sisters. "[35] Cave entrances measure from 100 m to 252 m wide and they are believed to be at least 73 m to 96 m deep. Because light does not reach the floor of most of the caves, it is likely that they extend much deeper than these lower estimates and widen below the surface. Dena is the only exception; its floor is visible and was measured to be 130 m deep. The interiors of these caverns may be protected from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface. A solar flare is a violent explosion in a star's (like the Sun 's atmosphere releasing as much Energy as 6 × 1025 Joules Solar flares [36] Some researchers have suggested that this protection makes the caves good candidates for future efforts to find liquid water and signs of life.

Mars has two permanent polar ice caps: the northern one at Planum Boreum and the southern one at Planum Australe. Planum Boreum ( Latin: "the northern plain" is the northern polar plain on Mars. Planum Australe ( Latin: "the southern plain" is the southern polar plain on Mars.

Atmosphere

Main article: Atmosphere of Mars
Mars's thin atmosphere, visible on the horizon in this low-orbit photo. Structure Mars' atmosphere is composed of the following major divisions Lower Atmosphere This is a warm region affected by heat from airborne Dust and

Mars lost its magnetosphere 4 billion years ago, so the solar wind interacts directly with the Martian ionosphere, keeping the atmosphere thinner than it would otherwise be by stripping away atoms from the outer layer. A magnetosphere' is a highly magnetized region around and possessed by an Astronomical object. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation Both Mars Global Surveyor and Mars Express have detected these ionised atmospheric particles trailing off into space behind Mars. The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched [37][38] The atmosphere of Mars is now relatively thin. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Atmospheric pressure on the surface varies from around 30 Pa (0. 03 kPa) on Olympus Mons to over 1155 Pa (1. 155 kPa) in the depths of Hellas Planitia, with a mean surface level pressure of 600 Pa (0. False color of Hellas Planitiajpeg|thumb|220px|This elevation map shows the surrounding elevated debris ring]] Hellas Planitia, also known as the Hellas Impact Basin 6 kPa). This is less than 1% of the surface pressure on Earth (101. 3 kPa). Mars's mean surface pressure equals the pressure found 35 km above the Earth's surface. The scale height of the atmosphere, about 11 km, is higher than Earth's (6 km) due to the lower gravity. A scale height is a term often used in scientific contexts for a distance over which a quantity decreases by a factor of e.

The atmosphere on Mars consists of 95% carbon dioxide, 3% nitrogen, 1. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 6% argon, and contains traces of oxygen and water. This article pertains to the chemical element For other uses see Argon (disambiguation. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the [3] The atmosphere is quite dusty, containing particulates about 1. 5 µm in diameter which give the Martian sky a tawny color when seen from the surface. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre [39]

Several researchers claim to have detected methane in the Martian atmosphere with a concentration of about 10 ppb by volume. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly [40][41] Since methane is an unstable gas that is broken down by ultraviolet radiation, typically lasting about 340 years in the Martian atmosphere,[42] its presence would indicate a current or recent source of the gas on the planet. This page is about the physical properties of gas as a state of matter Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Volcanic activity, cometary impacts, and the presence of methanogenic microbial life forms are among possible sources. Plate tectonics and hotspots Divergent plate boundaries At the A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Methanogens are Archaea that produce Methane as a Metabolic byproduct in Anoxic conditions A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually It was recently pointed out that methane could also be produced by a non-biological process called serpentinization[b] involving water, carbon dioxide, and the mineral olivine, which is known to be common on Mars. Serpentinite is a rock composed of one or more Serpentine Minerals Minerals in this group are formed by serpentinization a hydration and metamorphic A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg [43]

During a pole's winter, it lies in continuous darkness, chilling the surface and causing 25–30% of the atmosphere to condense out into thick slabs of CO2 ice (dry ice). Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Dry ice is solid Carbon dioxide. It is commonly used as a versatile cooling agent [44] When the poles are again exposed to sunlight, the frozen CO2 sublimes, creating enormous winds that sweep off the poles as fast as 400 km/h. Sublimation of an element or compound is a transition from the Solid to Gas phase with no intermediate liquid stage These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds. Frost is the solid deposition of Water vapor from saturated air Cirrus clouds are characterized by thin wisplike strands often accompanied by tufts leading to their common (non-standard name of 'mare's tail' Clouds of water-ice were photographed by the Opportunity rover in 2004. MER-B ( Mars Exploration Rover - B) known as Opportunity, is the second of the two rovers of NASA 's Mars Exploration [45]

Climate

Main article: Climate of Mars
Mars from Hubble Space Telescope October 28, 2005 with dust storm visible. The climate of Mars has been an issue of scientific curiosity for centuries due not least to the fact that Mars is the only terrestrial planet whose surface can be directly The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into Events 306 - Maxentius is proclaimed Roman Emperor. 312 - Battle of Milvian Bridge: Constantine Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar.

Of all the planets, Mars's seasons are the most Earth-like, due to the similar tilts of the two planets' rotational axes. However, the lengths of the Martian seasons are about twice those of Earth's, as Mars’ greater distance from the Sun leads to the Martian year being about two Earth years in length. Martian surface temperatures vary from lows of about −140 °C (-220 °F) during the polar winters to highs of up to 20 °C (68 °F) in summers. The Celsius Temperature scale was previously known as the centigrade scale. [11] The wide range in temperatures is due to the thin atmosphere which cannot store much solar heat, the low atmospheric pressure, and the low thermal inertia of Martian soil. Volumetric heat capacity ( VHC) describes the ability of a given Volume of a substance to store Internal energy while undergoing a given Temperature [46]

If Mars had an Earth-like orbit, its seasons would be similar to Earth's because its axial tilt is similar to Earth's. However, the comparatively large eccentricity of the Martian orbit has a significant effect. Mars is near perihelion when it is summer in the southern hemisphere and winter in the north, and near aphelion when it is winter in the southern hemisphere and summer in the north. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from As a result, the seasons in the southern hemisphere are more extreme and the seasons in the northern are milder than would otherwise be the case. The summer temperatures in the south can be up to 30 °C (54 °F) warmer than the equivalent summer temperatures in the north. [47]

Mars's northern ice cap.

Mars also has the largest dust storms in our Solar System. These can vary from a storm over a small area, to gigantic storms that cover the entire planet. They tend to occur when Mars is closest to the Sun, and have been shown to increase the global temperature. [48]

The polar caps at both poles consist primarily of water ice. However, there is dry ice present on their surfaces. Frozen carbon dioxide (dry ice) accumulates as a thin layer about one metre thick on the north cap in the northern winter only, while the south cap has a permanent dry ice cover about eight metres thick. [49] The northern polar cap has a diameter of about 1,000 kilometres during the northern Mars summer,[50] and contains about 1. 6 million cubic kilometres of ice, which if spread evenly on the cap would be 2 kilometres thick. [51] (This compares to a volume of 2. 85 million cubic kilometres for the Greenland ice sheet. The Greenland Ice Sheet is a vast body of ice covering 171 million km² roughly 80% of the surface of Greenland. ) The southern polar cap has a diameter of 350 km and a thickness of 3 km. [52] The total volume of ice in the south polar cap plus the adjacent layered deposits has also been estimated at 1. 6 million cubic kilometres. [53] Both polar caps show spiral troughs, which are believed to form as a result of differential solar heating, coupled with the sublimation of ice and condensation of water vapor. [54][55] Both polar caps shrink and regrow following the temperature fluctuation of the Martian seasons.

Orbit and rotation

Mars’ average distance from the Sun is roughly 230 million km (1. 5 AU) and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35. Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars 244 seconds. A Martian year is equal to 1. 8809 Earth years, or 1 year, 320 days, and 18. 2 hours.

Mars's axial tilt is 25. 19 degrees, which is similar to the axial tilt of the Earth. As a result, Mars has seasons like the Earth, though on Mars they are about twice as long given its longer year. Mars passed its perihelion in June 2007 and its aphelion in May 2008.

Mars has a relatively pronounced orbital eccentricity of about 0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 09; of the seven other planets in the Solar System, only Mercury shows greater eccentricity. However, it is known that in the past Mars has had a much more circular orbit than it does currently. At one point 1. 35 million Earth years ago, Mars had an eccentricity of roughly 0. 002, much less than that of Earth today. [56] The Mars cycle of eccentricity is 96,000 Earth years compared to the Earth's cycle of 100,000 years. [57] However, Mars also has a much longer cycle of eccentricity with a period of 2. 2 million Earth years, and this overshadows the 96,000 year cycle in the eccentricity graphs. For the last 35,000 years Mars' orbit has been getting slightly more eccentric because of the gravitational effects of the other planets. The closest distance between the Earth and Mars will continue to mildly decrease for the next 25,000 years. [58]

 The image to the left shows a comparison between Mars and Ceres, a dwarf planet in the Asteroid Belt, as seen from the ecliptic pole, while the image to the right is as seen from the ascending node. Ceres (ˈsɪəriːz A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. The ecliptic is the apparent path that the Sun traces out in the sky during the year The segments of orbits below the ecliptic are plotted in darker colors. The perihelia (q) and aphelia (Q) are labelled with the date of the nearest passage. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from

Moons

Phobos (left) and Deimos (right)

Mars has two tiny natural moons, Phobos and Deimos, which orbit very close to the planet and are thought to be captured asteroids. Mars has two tiny moons, Phobos and Deimos, which are thought to be captured Asteroids If viewed from the surface TemplateInfobox Planet.--> Deimos (ˈdaɪməs; also /ˈdiːməs/ [59]

Both satellites were discovered in 1877 by Asaph Hall, and are named after the characters Phobos (panic/fear) and Deimos (terror/dread) who, in Greek mythology, accompanied their father Ares, god of war, into battle. Asaph Hall ( October 15, 1829 &ndash November 22, 1907) was an American astronomer who is most famous for having discovered Phobos ( Ancient Greek, "Fear" is the embodiment of Fear and horror in Greek mythology. In Greek mythology, Deimos ( Δεῖμος &ndash " dread " was the Personification of dread. Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance In Greek mythology, Ares ( Ancient Greek:, Μodern Greek Άρης) is the son of Zeus and Hera. Ares was known as Mars to the Romans. [60]

From the surface of Mars, the motions of Phobos and Deimos appear very different from that of our own moon. Phobos rises in the west, sets in the east, and rises again in just 11 hours. Deimos, being only just outside synchronous orbit—where the orbital period would match the planet's period of rotation—rises as expected in the east but very slowly. A synchronous orbit is an Orbit in which an orbiting body (usually a Satellite) has a period equal to the average rotational period of the body being orbited (usually Despite the 30 hour orbit of Deimos, it takes 2. 7 days to set in the west as it slowly falls behind the rotation of Mars, then just as long again to rise. [61]

Because Phobos' orbit is below synchronous altitude, the tidal forces from the planet Mars are gradually lowering its orbit. The tidal force is a secondary effect of the Force of Gravity and is responsible for the Tides It arises because the gravitational acceleration experienced In about 50 million years it will either crash into Mars’ surface or break up into a ring structure around the planet. [61]

It is not well understood how or when Mars came to capture its two moons. Both have circular orbits, very near the equator, which is very unusual in itself for captured objects. For other meanings of the term "orbit" see Orbit (disambiguation In Astrodynamics or Celestial mechanics a circular Phobos's unstable orbit would seem to point towards a relatively recent capture. There is no known mechanism for an airless Mars to capture a lone asteroid, so it is likely that a third body was involved—however, asteroids as large as Phobos and Deimos are rare, and binaries rarer still, outside the asteroid belt. [62]

Life

Main article: Life on Mars

The current understanding of planetary habitability—the ability of a world to develop and sustain life—favors planets that have liquid water on their surface. Scientists have long speculated about the possibility of life on Mars owing to the planet's proximity and similarity to Earth. Planetary habitability is the measure of a Planet 's or a Natural satellite 's potential to develop and sustain Life. This requires that the orbit of a planet lie within a habitable zone, which for the Sun is currently occupied by Earth. In Astronomy a habitable zone ( HZ) is a region of space where conditions are favorable for Life as it may be found on Earth. Mars orbits half an astronomical unit beyond this zone and this, along with the planet's thin atmosphere, causes water to freeze on its surface. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the The past flow of liquid water, however, demonstrates the planet's potential for habitability. Recent evidence has suggested that any water on the Martian surface would have been too salty and acidic to support life. [63]

The lack of a magnetosphere and extremely thin atmosphere of Mars are a greater challenge: the planet has little heat transfer across its surface, poor insulation against bombardment and the solar wind, and insufficient atmospheric pressure to retain water in a liquid form (water instead sublimates to a gaseous state). In thermal physics, heat transfer is the passage of Thermal energy from a hot to a colder body The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. Mars is also nearly, or perhaps totally, geologically dead; the end of volcanic activity has stopped the recycling of chemicals and minerals between the surface and interior of the planet. [64]

Evidence suggests that the planet was once significantly more habitable than it is today, but whether living organisms ever existed there is still unclear. The Viking probes of the mid-1970s carried experiments designed to detect microorganisms in Martian soil at their respective landing sites, and had some apparently positive results, including a temporary increase of CO2 production on exposure to water and nutrients. NASA 's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. However this sign of life was later disputed by many scientists, resulting in a continuing debate, with NASA scientist Gilbert Levin asserting that Viking may have found life. Gilbert Levin is an American Engineer, the founder of Spherix and famous for experiments on Mars soil by the Viking Program and the A re-analysis of the now 30-year-old Viking data, in light of modern knowledge of extremophile forms of life, has suggested that the Viking tests were also not sophisticated enough to detect these forms of life. An extremophile is an Organism that thrives in and may even require Physically or Geochemically extreme conditions that are detrimental to the The tests may even have killed a (hypothetical) life form. [65]

At the Johnson space center lab organic compounds have been found in the meteorite ALH84001, which is supposed to have come from Mars. The Lyndon B Johnson Space Flight Center ( "JSFC") is the National Aeronautics and Space Administration 's center for A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface ALH 84001 (full name Allan Hills 84001) is a Meteorite found in Allan Hills, Antarctica in December 1984 by a team of US meteorite hunters from They concluded that these were deposited by primitive life forms extant on Mars before the meteorite was blasted into space by a meteor strike and sent on a 15 million-year voyage to Earth. Also, small quantities of methane and formaldehyde recently detected by Mars orbiters are both claimed to be hints for life, as these chemical compounds would quickly break down in the Martian atmosphere. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. [66][67] It is possible that these compounds may be replenished by volcanic or geological means such as serpentinization. Serpentinite is a rock composed of one or more Serpentine Minerals Minerals in this group are formed by serpentinization a hydration and metamorphic [43]

Exploration

Main article: Exploration of Mars
Mars 3 Lander (stamp, 1972)

Dozens of spacecraft, including orbiters, landers, and rovers, have been sent to Mars by the Soviet Union, the United States, Europe, and Japan to study the planet's surface, climate, and geology. The exploration of Mars has been an important part of the Space exploration programs of the Soviet Union (later Russia) the United The Mars program was a series of Mars unmanned Landers and Orbiters launched by the Soviet Union in the early 1970s. Viking 1 was the first of two spacecraft sent to Mars as part of NASA 's Viking program, and holds the record for the longest Mars surface mission A spacecraft is a Vehicle or machine designed for Spaceflight. For other meanings see Orbiter (disambiguation. An orbiter is a Space probe that Orbits a Planet or Natural A rover is a Space exploration vehicle designed to move across the surface of a Planet or other Astronomical body. The Soviet space program consisted of initiatives within the Soviet Union by competing design groups The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member The, or JAXA, is Japan's national Aerospace agency JAXA was formed on October 1 2003 as an Independent Administrative Institution through the

Roughly two-thirds of all spacecraft destined for Mars have failed in one manner or another before completing or even beginning their missions. While this high failure rate can be ascribed to technical problems, enough have either failed or lost communications for causes unknown for some to search for other explanations. Examples include an Earth-Mars "Bermuda Triangle", a Mars Curse, or even the long-standing NASA in-joke, the "Great Galactic Ghoul" that feeds on Martian spacecraft. The Bermuda Triangle, also known as the Devil's Triangle, is a region of the northwestern Atlantic Ocean in which a number of Aircraft and surface The exploration of Mars has been an important part of the Space exploration programs of the Soviet Union (later Russia) the United The exploration of Mars has been an important part of the Space exploration programs of the Soviet Union (later Russia) the United [68]

Past missions

The first successful fly-by mission to Mars was NASA's Mariner 4, launched in 1964. Mariner 4 (Mariner-Mars 1964 was the fourth in a series of spacecraft intended for planetary exploration in a flyby mode and performed the first successful The first successful objects to land on the surface were two Soviet probes, Mars 2 and Mars 3 from the Mars probe program, launched in 1971, but both lost contact within seconds of landing. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 The Mars program was a series of Mars unmanned Landers and Orbiters launched by the Soviet Union in the early 1970s. The Mars program was a series of Mars unmanned Landers and Orbiters launched by the Soviet Union in the early 1970s. This article is for the Russian (Soviet series of space probes for the moon designated as Mars II see Deimos (moon; for all missions to Mars see Exploration Then came the 1975 NASA launches of the Viking program, which consisted of two orbiters, each having a lander; both landers successfully touched down in 1976. NASA 's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Viking 1 remained operational for six years, Viking 2 for three. Viking 1 was the first of two spacecraft sent to Mars as part of NASA 's Viking program, and holds the record for the longest Mars surface mission The Viking 2 mission was part of the Viking program to Mars, and consisted of an orbiter and a lander essentially identical to that of the Viking 1 The Viking landers relayed the first color pictures of Mars[69] and also mapped the surface of Mars so well that the images are still sometimes used to this day.

The Soviet probes Phobos 1 and 2 were sent to Mars in 1988 to study Mars and its two moons. The Phobos (Фобос Fobos program was an Unmanned space mission consisting of two probes launched by the Soviet Union to study Phobos 1 lost contact on the way to Mars. Phobos 2, while successfully photographing Mars and Phobos, failed just before it was set to release two landers on Phobos's surface.

Following the 1992 failure of the Mars Observer orbiter, NASA launched the Mars Global Surveyor in 1996. Mars Observer, launched by NASA in September 25, 1992, was the first of the proposed Observer series of planetary missions and was designed The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched This mission was a complete success, having finished its primary mapping mission in early 2001. Contact was lost with the probe in November 2006 during its third extended program, spending exactly 10 operational years in space. Only a month after the launch of the Surveyor, NASA launched the Mars Pathfinder, carrying a robotic exploration vehicle Sojourner, which landed in the Ares Vallis on Mars. The Mars Pathfinder was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor Ares Vallis is a Valley on Mars which appears to have been carved by fluids perhaps Water. This mission was also successful, and received much publicity, partially due to the many images that were sent back to Earth. [70]

Current missions

Spirit's lander on Mars

In 2001 NASA launched the successful Mars Odyssey orbiter, which is still in orbit as of March 2008, and the ending date has been extended to September 2008. MER-A ( Mars Exploration Rover - A) known as Spirit, is the first of the two rovers of NASA 's Mars Exploration Rover 2001 Mars Odyssey is a Robotic spacecraft Orbiting the planet Mars. Odyssey's Gamma Ray Spectrometer detected significant amounts of hydrogen in the upper metre or so of Mars's regolith. A Gamma-Ray Spectrometer, or (GRS is an instrument for measuring the distribution (or Spectrum —see figure) of the intensity of gamma radiation versus the energy Regolith ( Greek: "blanket rock" is a layer of loose Heterogeneous material covering solid rock. This hydrogen is thought to be contained in large deposits of water ice. [71]

In 2003, the ESA launched the Mars Express craft, consisting of the Mars Express Orbiter and the lander Beagle 2. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member Mars Express is a Space exploration mission being conducted by the European Space Agency (ESA Beagle 2 was an unsuccessful British landing spacecraft that formed part of the European Space Agency 's 2003 Mars Express mission Beagle 2 failed during descent and was declared lost in early February 2004. [72] In early 2004 the Planetary Fourier Spectrometer team announced it had detected methane in the Martian atmosphere. The Planetary Fourier Spectrometer ( PFS) is an Infrared Spectrometer built by the Istituto Nazionale di Astrofisica (Italian National Institute ESA announced in June 2006 the discovery of aurorae on Mars. [73]

Also in 2003, NASA launched the twin Mars Exploration Rovers named Spirit (MER-A) and Opportunity (MER-B). NASA 's Mars Exploration Rover ( MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of MER-A ( Mars Exploration Rover - A) known as Spirit, is the first of the two rovers of NASA 's Mars Exploration Rover MER-B ( Mars Exploration Rover - B) known as Opportunity, is the second of the two rovers of NASA 's Mars Exploration Both missions landed successfully in January 2004 and have met or exceeded all their targets. Among the most significant scientific returns has been conclusive evidence that liquid water existed at some time in the past at both landing sites. Martian dust devils and windstorms have occasionally cleaned both rovers' solar panels, and thus increased their lifespan. A dust devil is a strong well-formed and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall to large (over 10 meters wide and over [74]

On August 12, 2005 the NASA Mars Reconnaissance Orbiter probe was launched toward the planet, arriving in orbit on March 10, 2006 to conduct a two-year science survey. Events 1099 - First Crusade: Battle of Ascalon - Crusaders under the command of Godfrey of Bouillon defeat Fatimid Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. NASA 's Mars Reconnaissance Orbiter ( MRO) is a multipurpose Spacecraft designed to conduct Reconnaissance and exploration of Mars Events 241 BC - First Punic War: Battle of the Aegates Islands - The Romans sink the Carthaginian fleet bringing Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. The orbiter will map the Martian terrain and weather to find suitable landing sites for upcoming lander missions. It also contains an improved telecommunications link to Earth, with more bandwidth than all previous missions combined.

The Mars Reconnaissance Orbiter snapped the first image of a series of active avalanches near the planet's north pole, scientists said March 3, 2008. NASA 's Mars Reconnaissance Orbiter ( MRO) is a multipurpose Spacecraft designed to conduct Reconnaissance and exploration of Mars This article refers to the natural event For other uses see Avalanche (disambiguation An avalanche is an abrupt and rapid flow of snow often The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is subject to the caveats explained below defined as the point in the northern Events 1284 - Statute of Rhuddlan incorporated the Principality of Wales into England 1575 - Indian 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common [75]

A prototype of the Phoenix lander practices robotic arm control at a test site in Death Valley. Phoenix is a Robotic spacecraft on a Space exploration mission on Mars under the Mars Scout Program. Death Valley is the lowest driest and hottest Valley in the United States.

The most recent mission to Mars is the NASA Phoenix Mars lander, which launched August 4, 2007 and arrived on the north polar region of Mars on May 25, 2008[76]. Phoenix is a Robotic spacecraft on a Space exploration mission on Mars under the Mars Scout Program. Events 70 - The Destruction of the Second Temple in Jerusalem by the Romans. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1085 - Alfonso VI of Castile takes Toledo Spain back from the Moors. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common The lander has a robotic arm with a 2. 5 m reach and capable of digging a meter into the Martian soil. The lander will be in an area with an 80% chance of ice being less than 30 cm below the surface, and has a microscopic camera capable of resolving to one-thousandth the width of a human hair. [77]

The Dawn spacecraft will fly by Mars in February 2009 for a gravity assist on its way to investigate Vesta and then Ceres. Dawn, launched on September 27 2007 is a Robotic spacecraft being sent by NASA on a Space exploration mission to the two most massive members TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Ceres (ˈsɪəriːz

Future missions

Phoenix will be followed by the Mars Science Laboratory in 2009, a bigger, faster (90 m/h), and smarter version of the Mars Exploration Rovers. The Mars Science Laboratory ( MSL) is a NASA rover scheduled to be launched on September 15, 2009 and perform the first ever Metre per hour (American spelling meter per hour is a metric unit of both Speed ( scalar) and Velocity ( Vector (geometry) Experiments include a laser chemical sample that can deduce the make-up of rocks at a distance of 13 m. [78]

The joint Russian and Chinese Phobos-Grunt sample-return mission, to return samples of Mars's moon Phobos, is scheduled for a 2009 launch. Phobos-Grunt ( Russian: Фобос-Грунт) is a planned Russian Sample return mission to Phobos, one of the moons of In 2013 the ESA plans to launch its first Rover to Mars, the ExoMars rover will be capable of drilling 2 m into the soil in search of organic molecules. ExoMars is a European-led Space exploration mission currently under development by the European Space Agency (ESA that will send a robotic rover to the [79][80]

The Finnish-Russian MetNet mission will consist of sending tens of small landers on the Martian surface in order to establish a wide-spread surface observation network to investigate the planet's atmospheric structure, physics and meteorology. MetNet is an atmospheric science mission to Mars, initiated and defined by the Finnish Meteorological Institute. [81] A precursor mission using 1-2 landers is scheduled for launch in 2009 or 2011. One possibility is a piggyback launch on the Russian Phobos Grunt mission. Phobos-Grunt ( Russian: Фобос-Грунт) is a planned Russian Sample return mission to Phobos, one of the moons of [82] Other launches will take place in the launch windows extending to 2019.

Manned Mars exploration by the United States has been explicitly identified as a long-term goal in the Vision for Space Exploration announced in 2004 by US President George W. Bush. A human mission to visit and land on the planet Mars has long been a subject for Science fiction writers and a dream of Space exploration advocates The Vision for Space Exploration is the United States space policy announced on January 14, 2004 by U George Walker Bush ( born July 6 1946 is the forty-third and current President of the United States. [83] NASA and Lockheed Martin have begun work on the Orion spacecraft, formerly the Crew Exploration Vehicle, which is currently scheduled to send a human expedition to Earth's moon by 2020 as a stepping stone to an expedition to Mars thereafter. Lockheed Martin ( is a large multinational Aerospace manufacturer and advanced technology Company formed in 1995 by the merger of Orion is a Spacecraft design currently under development by the United States space agency NASA.

The European Space Agency hopes to land humans on Mars between 2030 and 2035. [84] This will be preceded by successively larger probes, starting with the launch of the ExoMars probe and a Mars Sample Return Mission. ExoMars is a European-led Space exploration mission currently under development by the European Space Agency (ESA that will send a robotic rover to the

On September 28, 2007, NASA administrator Michael D. Griffin stated that NASA aims to put a man on Mars by 2037: in 2057, we should be celebrating 20 years of man on Mars. Events 48 BC - Pompey the Great is assassinated on orders of King Ptolemy of Egypt after landing in Egypt. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. For other people with the same name see Michael Griffin (disambiguation. [85]

Astronomy on Mars

Main article: Astronomy on Mars
Photograph of a Martian sunset taken by Spirit at Gusev crater, May 19, 2005. This article presents information and images about viewing astronomical phenomena from the planet Mars. Gusev Crater is a crater on the planet Mars and is located at 175 Events 1535 - French explorer Jacques Cartier sets sail on his second voyage to North America with three ships 110 men and Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar.

With the existence of various orbiters, landers, and rovers, it is now possible to study astronomy from the Martian skies. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study The Earth and the Moon are easily visible while Mars’ moon Phobos appears about one third the angular diameter of the full Moon as it appears from Earth. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle On the other hand Deimos appears more or less star-like, and appears only slightly brighter than Venus does from Earth. [86]

There are also various phenomena well-known on Earth that have now been observed on Mars, such as meteors and auroras. [73] A transit of the Earth as seen from Mars will occur on November 10, 2084. A transit of Earth across the Sun as seen from Mars takes place when the planet Earth passes directly between the Sun and Mars obscuring Events 1444 - Battle of Varna: The crusading forces of King Vladislaus III of Varna (aka Ulaszlo I of Hungary and Wladyslaw Notable predictions and known events 2082 All Classified information held by the British Government about the Falklands War There are also transits of Mercury and transits of Venus, and the moon Deimos is of sufficiently small angular diameter that its partial "eclipses" of the Sun are best considered transits (see Transit of Deimos from Mars). A transit of Mercury across the Sun as seen from Mars takes place when the planet Mercury passes directly between the Sun and Mars obscuring A transit of Venus across the Sun as seen from Mars takes place when the planet Venus passes directly between the Sun and Mars obscuring a small A transit of Deimos across the Sun as seen from Mars takes place when Deimos passes directly between the Sun and a point on the surface of Mars obscuring

Viewing

To the naked-eye, Mars usually appears a distinct yellow, orange, or reddish color, and varies in brightness more than any other planet as seen from Earth over the course of its orbit. The apparent magnitude of Mars varies from +1. The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 8 at conjunction to as high as -2. 9 at perihelic opposition. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from Opposition is a term used in Positional astronomy and Astrology to indicate when one celestial body is on the opposite side of the sky when viewed from [3] When farthest away from the Earth, it is more than seven times as far from the latter as when it is closest. When least favourably positioned, it can be lost in the Sun's glare for months at a time. At its most favourable times—which occur twice every 32 years, alternately at 15 and 17-year intervals, and always between late July and late September—Mars shows a wealth of surface detail to a telescope. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Especially noticeable, even at low magnification, are the polar ice caps. A polar ice cap is a high- Latitude region of a Planet or moon that is covered in Ice. [87]

The point of Mars’ closest approach to the Earth is known as opposition. The length of time between successive oppositions, or the synodic period, is 780 days. The orbital period is the time taken for a given object to make one complete Orbit about another object Because of the eccentricities of the orbits, the times of opposition and minimum distance can differ by up to 8. 5 days. The minimum distance varies between about 55 and 100 million km due to the planets' elliptical orbits. In Mathematics, an ellipse (from the Greek ἔλλειψις literally absence) is a Conic section, the locus of points in a [3] The next Mars opposition will occur on January 29, 2010. Events 904 - Sergius III comes out of retirement to take over the papacy from the deposed Antipope Christopher. For the film see 2010 The Year We Make Contact. For the book see 2010 Odyssey Two.

As Mars approaches opposition it begins a period of retrograde motion, which means it will appear to move backwards in a looping motion with respect to the background stars. Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion.

2003 closest approach

The rotation of Mars as seen in a small telescope in 2003.
Mars oppositions from 2003-2018, viewed from above the ecliptic with the Earth centered.

On August 27, 2003, at 9:51:13 UT, Mars made its closest approach to Earth in nearly 60,000 years: 55,758,006 km. Events 479 BC - Greco-Persian Wars: Persian forces led by Mardonius are routed by Pausanias, the Spartan Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. This occurred when Mars was one day from opposition and about three days from its perihelion, making Mars particularly easy to see from Earth. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from The last time it came so close is estimated to have been on September 12, 57,617 BC, the next time being in 2287. Events 1213 - Albigensian Crusade: Simon de Montfort 5th Earl of Leicester, defeats Peter II of Aragon at the The Middle Paleolithic (or Middle Palaeolithic) is the second subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, However, this record approach was only very slightly closer than other recent close approaches. For instance, the minimum distance on August 22, 1924 was 0. Events 392 - Arbogast has Eugenius elected Western Roman Emperor. Year 1924 ( MCMXXIV) was a Leap year starting on Tuesday (link will display the full calendar of the Gregorian calendar. 37284 AU, compared with 0. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the 37271 AU on August 27, 2003, and the minimum distance on August 24, 2208 will be 0. Events 479 BC - Greco-Persian Wars: Persian forces led by Mardonius are routed by Pausanias, the Spartan Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Events 49 BC - Julius Caesar 's General Gaius Scribonius Curio is defeated in the Second Battle of the Bagradas River The 23rd century of the Anno Domini ( common) era will span the years 2201&ndash2300 of the Gregorian calendar. 37278 AU. [88] The orbital changes of Earth and Mars are making the approaches nearer: the 2003 record will be bettered 22 times by the year 4000.

Historical observations

The history of observations of Mars is 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 about every 15–17 years, and are distinguished because Mars is close to perihelion, making it even closer to Earth. Aristotle was among the first known writers to describe observations of Mars, noting that, as it passed behind the Moon, it was farther away than was originally believed. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great.

The only occultation of Mars by Venus observed was that of October 3, 1590, seen by M. Möstlin at Heidelberg. In Shia Islam The Occultation is a term used to designate the hidden state of the Imam of the Time. Events 42 BC - First Battle of Philippi: Triumvirs Mark Antony and Octavian fight an indecisive battle with Caesar's Michael Maestlin (also Mästlin Möstlin or Moestlin ( 30 September 1550 in Göppingen, Germany - 20 October 1631) was a Heidelberg is a city in Baden-Württemberg, Germany. As of 2006 over 140000 people live within the city's area [89]

In 1609, Mars was viewed by Galileo, who was first to see it via telescope.

Map of Mars by Giovanni Schiaparelli.

By the 19th century, the resolution of telescopes reached a level sufficient for surface features to be identified. In September 1877, a perihelic opposition of Mars occurred on September 5. Events 1590 - Alexander Farnese 's army forces Henry IV of France to raise the siege of Paris. In that year, Italian astronomer Giovanni Schiaparelli, then in Milan, used a 22 cm telescope to help produce the first detailed map of Mars. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Honors and Awards Awards Gold Medal of the Royal Astronomical Society (1872 Bruce Medal (1902 Named Milan (Milano Milan (listen) is one of the largest cities in Italy, located in the plains of Lombardy. These maps notably contained features he called canali, which were later shown to be an optical illusion. This article is about visual perception See Optical Illusion (Album for information about the Time Requiem album 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. [90]

Mars sketched as observed by Lowell sometime before 1914. (South top)

Influenced by the observations the orientalist Percival Lowell founded an observatory which had a 300 and 450 mm telescope. Percival Lawrence Lowell ( March 13, 1855 – November 12, 1916) was a businessman author mathematician and Astronomer who fueled Lowell Observatory is an astronomical Observatory in Flagstaff Arizona. The observatory was used for the exploration of Mars during the last good opportunity in 1894 and the following less favorable oppositions. He published several books on Mars and life on the planet, which had a great influence on the public. The canali were also found by other astronomers, like Henri Joseph Perrotin and Louis Thollon in Nice, using one of the largest telescopes of that time. Henri Joseph Anastase Perrotin ( December 19 1845 &ndash February 29 1904) was a French Astronomer. Nice (nis Niçard Occitan: Niça norm or Nissa, Italian: Nizza or Nizza Marittima, Greek

The seasonal changes (consisting of the diminishing of the polar caps and the dark areas formed during Martian summer) in combination with the canals lead to speculation about life on Mars, and it was a long held belief that Mars contained vast seas and vegetation. The telescope never reached the resolution required to give proof to any speculations. However, as bigger telescopes were used, fewer long, straight canali were observed. During an observation in 1909 by Flammarion with a 840 mm telescope, irregular patterns were observed, but no canali were seen. Nicolas Camille Flammarion ( February 26 1842 &ndash June 3 1925) was a French Astronomer and author [91]

Map of Mars from Hubble Space Telescope as seen near the 1999 opposition. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into (North top)

Even in the 1960s articles were published on Martian biology, putting aside explanations other than life for the seasonal changes on Mars. Detailed scenarios for the metabolism and chemical cycles for a functional ecosystem have been published. [92]

It was not until spacecraft visited the planet during NASA's Mariner missions in the 1960s that these myths were dispelled. A spacecraft is a Vehicle or machine designed for Spaceflight. The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes The results of the Viking life-detection experiments started an intermission in which the hypothesis of a hostile, dead planet was generally accepted.

Some maps of Mars were made using the data from these missions, but it was not until the Mars Global Surveyor mission, launched in 1996 and operated until late 2006, that complete, extremely detailed maps were obtained. The Mars Global Surveyor ( MGS) was a US Spacecraft developed by NASA and the Jet Propulsion Laboratory and launched These maps are now available online. [93]

Mars in culture

Historical connections

Mars is named after the Roman god of war. Ancient Rome was a Civilization that grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC Mars was the Roman Warrior god, the son of Juno and Jupiter, husband of Bellona, and the lover of Venus. In Babylonian astronomy, the planet was named after Nergal, their deity of fire, war, and destruction, most likely due to the planet's reddish appearance. Babylonia was an Amorite state in lower Mesopotamia (modern southern Iraq) with Babylon as its capital The name Nergal (or Nirgal, Nirgali) refers to a Deity in Babylonia with the main seat See also List of deities A deity is a Postulated Preternatural or Supernatural Being, who is always [94] When the Greeks equated Nergal with their god of war, Ares, they named the planet Ἄρεως ἀστἡρ (Areos aster), or "star of Ares". The term ancient Greece refers to the period of Greek history lasting from the Greek Dark Ages ca Then, following the identification of Ares and Mars, it was translated into Latin as stella Martis, or "star of Mars", or simply Mars. Interpretatio graeca is a Latin term for the common tendency of Ancient Greek writers to equate foreign divinities to members of their own pantheon The Greeks also called the planet Πυρόεις Pyroeis meaning "fiery". In Hindu mythology, Mars is known as Mangala (मंगल). Hindu mythology is the large body of Mythology related to Hinduism, notably as contained in Sanskrit literature, such as the Sanskrit epics and In Jyotish Astrology, Mangala ( Devanagari: मंगल is the name for Mars, the red planet The planet is also called Angaraka in Sanskrit, after the celibate god of war, who possesses the signs of Aries and Scorpio, and teaches the occult sciences. Sanskrit (sa संस्कृता वाक् saṃskṛtā vāk, for short sa संस्कृतम् saṃskṛtam) is a historical Celibacy refers to the lack of participation in Sexual intercourse. Aries, the ram, is the first Astrological sign in the Zodiac. The planet was known by the Egyptians as "Ḥr Dšr";;;; or "Horus the Red". Ancient Egypt was an Ancient Civilization in eastern North Africa, concentrated along the lower reaches of the Nile River in what is now The Hebrews named it Ma'adim (מאדים)—"the one who blushes"; this is where one of the largest canyons on Mars, the Ma'adim Vallis, gets its name. Hebrews (or Hebertes, Eberites, Hebreians, " Habiru " or " Habiri " Hebrew: עברים For the song see CANYONMID. For the band see Canyon (band. A canyon (rarely cañon) or gorge Ma'adim Vallis is one of the largest Canyons on Mars, about 700 km long and significantly larger than Earth's Grand Canyon. It is known as al-Mirrikh in Arabic, and Merih in Turkish. In Urdu and Persian it is written as مریخ and known as "Merikh". Urdu ( ur '''{{Nastaliq اردو}}''' trans Urdū, historically spelled Ordu) is a Central Indo-Aryan language Urdu is a standardised The etymology of al-Mirrikh is unknown. Ancient Persians named it Bahram, the Zoroastrian god of faith and it is written as بهرام. Ancient Turks called it Sakit. The Chinese, Japanese, Korean and Vietnamese cultures refer to the planet as 火星, or the fire star, a name based on the ancient Chinese mythological cycle of Five elements. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National For a topic outline on this subject see List of basic Japan topics. Korea is a geographic area composed of two sovereign countries a civilization and a former state situated on the Korean Peninsula in East Asia. Vietnam (ˌviːɛtˈnɑːm Việt Nam) officially In traditional Chinese philosophy, natural phenomena can be classified into the Wu Xing ( or the Five Phases, usually translated as five elements,

Its symbol, derived from the astrological symbol of Mars, is a circle with a small arrow pointing out from behind. Astrological symbols are images used in various astrological systems to denote relevant objects It is a stylized representation of a shield and spear used by the Roman God Mars. Mars in Roman mythology was the God of War and patron of warriors. This symbol is also used in biology to describe the male sex, and in alchemy to symbolise the element iron which was considered to be dominated by Mars whose characteristic red colour is coincidentally due to iron oxide. Alchemy a part of the Occult Tradition is both a philosophy and a practice with an ultimately unknown aim involving the improvement of the alchemist as well as the making of Alchemic symbols, originally devised as part of the Protoscience of Alchemy, were used to denote some elements and some compounds until the 18th century [95] ♂ occupies Unicode position U+2642. In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's

Intelligent "Martians"

An 1893 soap ad playing on the popular idea that Mars was populated.

The popular idea that Mars was populated by intelligent Martians exploded in the late 19th century. As an adjective the term "martian" is used to describe anything pertaining to the Planet Mars. Schiaparelli's "canali" observations combined with Percival Lowell's books on the subject put forward the standard notion of a planet that was a drying, cooling, dying world with ancient civilizations constructing irrigation works. Honors and Awards Awards Gold Medal of the Royal Astronomical Society (1872 Bruce Medal (1902 Named Percival Lawrence Lowell ( March 13, 1855 – November 12, 1916) was a businessman author mathematician and Astronomer who fueled [96]

Many other observations and proclamations by notable personalities added to what has been termed "Mars Fever". [97] In 1899 while investigating atmospheric radio noise using his receivers in his Colorado Springs lab, inventor Nikola Tesla observed repetitive signals that he later surmised might have been radio communications coming from another planet, possibly Mars. There have already been discussions about Tesla's ethnicity on the talk page In a 1901 interview Tesla said:

 “ It was some time afterward when the thought flashed upon my mind that the disturbances I had observed might be due to an intelligent control. Although I could not decipher their meaning, it was impossible for me to think of them as having been entirely accidental. The feeling is constantly growing on me that I had been the first to hear the greeting of one planet to another. [98] ”

Tesla's theories gained support from Lord Kelvin who, while visiting the United States in 1902, was reported to have said that he thought Tesla had picked up Martian signals being sent to the United States. William Thomson 1st Baron Kelvin (or Lord Kelvin) OM, GCVO, PC, PRS, FRSE, (26 June 1824 &ndash 17 December 1907 The United States of America —commonly referred to as the [99] However, Kelvin "emphatically" denied this report shortly before departing America: "What I really said was that the inhabitants of Mars, if there are any, were doubtless able to see New York, particularly the glare of the electricity. "[100]

In a New York Times article in 1901, Edward Charles Pickering, director of the Harvard College Observatory, said that they had received a telegram from Lowell Observatory in Arizona that seemed to confirm that Mars was trying to communicate with the Earth. Edward Charles Pickering ( July 19 1846 – February 3 1919) was an American Astronomer and Physicist, brother The Harvard College Observatory (or HCO is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Department of Astronomy Lowell Observatory is an astronomical Observatory in Flagstaff Arizona. The State of Arizona ( is a state located in the southwestern region of the United States. [101]

 “ Early in December of 1900, we received from Lowell Observatory in Arizona a telegram that a shaft of light had been seen to project from Mars (the Lowell observatory makes a specialty of Mars) lasting seventy minutes. I wired these facts to Europe and sent out neostyle copies through this country. The observer there is a careful, reliable man and there is no reason to doubt that the light existed. It was given as from a well-known geographical point on Mars. That was all. Now the story has gone the world over. In Europe it is stated that I have been in communication with Mars, and all sorts of exaggerations have spring up. Whatever the light was, we have no means of knowing. Whether it had intelligence or not, no one can say. It is absolutely inexplicable. [101] ”

Pickering later proposed creating a set of mirrors in Texas with the intention of signaling Martians. Texas ( is a state geographically located in the South Central United States and is also known as the Lone Star State.

It should be noted that pulsars (more properly neutron stars) emit electromagnetic radiation, usually low frequency waves, such as radio waves. They do this quite regularly, up to such a point that some observatories use them as clocks. Nikola Tesla may not have witnessed a message from aliens because he only had one reading from a single telescope (the problem with this is that it only determines the direction of the signal. To determine the position in three dimension, two observers are needed. Since fields of radio telescopes did not exist in his time and he did not notice until after, it is highly unlikely he observed the radio signals from two different locations).

In fiction

Main article: Mars in fiction

The depiction of Mars in fiction has been stimulated by its dramatic red color and by early scientific speculations that its surface conditions not only might support life, but intelligent life. Fictional representations of Mars have been popular for over a century

Alien tripod illustration from the 1906 French edition of H. G. Wells' The War of the Worlds.

Thus originated a large number of science fiction scenarios, the best known of which is H. G. Wells' The War of the Worlds, in which Martians seek to escape their dying planet by invading Earth. Herbert George Wells (21 September 1866 &ndash 13 August 1946 He was an outspoken socialist and a pacifist, his later works becoming increasingly political The War of the Worlds (1898 by H G Wells, is an early Science fiction Novel which describes an invasion of England by A subsequent radio version of The War of the Worlds on October 30, 1938 was presented as a live news broadcast, and many listeners mistook it for the truth. Events 637 - Antioch surrenders to the Muslim forces under Rashidun Caliphate after the Battle of Iron bridge. Year 1938 ( MCMXXXVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar. [102]

Also influential were Ray Bradbury's The Martian Chronicles, in which human explorers accidentally destroy a Martian civilization, Edgar Rice Burroughs' Barsoom series and a number of Robert A. Heinlein stories before the mid-sixties. The Martian Chronicles is a 1950 Science fiction story collection by Ray Bradbury that chronicles the colonization of Mars by humans Edgar Rice Burroughs ( September 1, 1875 – March 19, 1950) was an American author best known for his creation of the jungle hero Barsoom is a fictional version of the planet Mars invented by author Edgar Rice Burroughs for a series of action adventure stories Robert Anson Heinlein (July 7 1907 – May 8 1988 was an American Novelist and Science fiction Writer.

Author Jonathan Swift made reference to the moons of Mars, about 150 years before their actual discovery by Asaph Hall, detailing reasonably accurate descriptions of their orbits, in the 19th chapter of his novel Gulliver's Travels. Jonathan Swift (30 November 1667 Asaph Hall ( October 15, 1829 &ndash November 22, 1907) was an American astronomer who is most famous for having discovered Gulliver's Travels (1726 amended 1735 officially Travels into Several Remote Nations of the World in Four Parts [103]

After the Mariner and Viking spacecraft had returned pictures of Mars as it really is, an apparently lifeless and canal-less world, these ideas about Mars had to be abandoned and a vogue for accurate, realist depictions of human colonies on Mars developed, the best known of which may be Kim Stanley Robinson's Mars trilogy. The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes NASA 's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Kim Stanley Robinson (born March 23 1952) is an American Science fiction Writer, probably best known for his award-winning However, pseudo-scientific speculations about the Face on Mars and other enigmatic landmarks spotted by space probes have meant that ancient civilizations continue to be a popular theme in science fiction, especially in film. Cydonia Mensae is an Albedo feature (region on the planet Mars ( named after a historic city state in Crete) A space probe is a scientific Space exploration mission in which a Robotic spacecraft leaves the Gravity well of Earth and approaches the [104]

Another popular theme, particularly among American writers, is the Martian colony that fights for independence from Earth. This is a major plot element in the novels of Greg Bear and Kim Stanley Robinson, as well as the movie Total Recall (based on a short story by Philip K. Dick) and the television series Babylon 5. Gregory Dale Bear (born August 20, 1951) is an American Science fiction and mainstream author Kim Stanley Robinson (born March 23 1952) is an American Science fiction Writer, probably best known for his award-winning Total Recall is a 1990 Academy Award -winning American Science fiction film. Philip Kindred Dick (December 16 – March 2) was an American Science fiction Novelist and Short story Writer. Babylon 5 is an American science fiction television series created produced and largely written by J Many video games also use this element, including Red Faction and the Zone of the Enders series. For the video game franchise by Volition see Red Faction (series Red Faction is a First-person shooter Zone of the Enders, also known as ZOE, is a Video game that was developed and published by Konami in Mars (and its moons) were also the setting for the popular Doom video game franchise and the later Martian Gothic. Doom (officially cased DOOM) is a 1993 Computer game by Id Software that is a landmark title in the First-person shooter Martian Gothic Unification (aka Martian Gothic) is a Survival horror game for the PlayStation and PC

In music

In Gustav Holst's The Planets, Mars is depicted as the "Bringer of War". Gustav Theodore Holst (21 September 1874 – 25 May 1934was an English Composer and was a music teacher for nearly 20 years The Planets Op 32 is a seven- movement Orchestral suite by the British composer Gustav Holst, written between 1914

Notes

1. ^ Best fit ellipsoid
2. ^ There are many serpentinization reactions. is a diameter Apollo class Near-Earth object and a Mars-crosser asteroid discovered on November 20[[ 007]] by Andrea Boattini Mars is the focus of much speculation and serious study about possible human colonization which might be possible The Darian Calendar is a proposed system of time-keeping designed to serve the needs of any possible future human settlers on the planet Mars. Extraterrestrial life is Life originating outside of the Earth. The following table is a partial list of artificial objects on the surface of Mars. What follows is a list of Chasmata on Mars. A chasma is a deep steep sided elongated depression similar to a Canyon on Earth. There are hundreds of thousands of craters on Mars, but only some of them have names Valles (singular Vallis) on Mars are similar to Valleys on Earth. The terraforming of Mars is the hypothetical process by which the climate, surface and known properties of Mars would be deliberately changed with the goal of making An ellipsoid is a type of quadric surface that is a higher dimensional analogue of an Ellipse. Serpentinite is a rock composed of one or more Serpentine Minerals Minerals in this group are formed by serpentinization a hydration and metamorphic Olivine is a solid solution between forsterite and fayalite whose general formula is (Fe,Mg)2SiO4. The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg A solid solution is a Solid - state Solution of one or more solutes in a Solvent. Forsterite (Mg2SiO4 is the magnesium rich end-member of the Olivine Solid solution series Fayalite (Fe2SiO4 is the Iron rich end-member of the Olivine solid-solution series The reaction producing methane from olivine can be written (in balanced form) as: Forsterite + Fayalite + Water + Carbonic acid → Serpentine + Magnetite + Methane , or: 18Mg2SiO4 + 6Fe2SiO4 + 26H2O + CO212Mg3Si2O5(OH)4 + 4Fe3O4 + CH4

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68. ^ Dinerman, Taylor (September 27, 2004). Is the Great Galactic Ghoul losing his appetite?. The space review. Retrieved on 2007-03-27. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 196 BC - Ptolemy V ascends to the throne of Egypt. 1309 - Pope Clement V excommunicates
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71. ^ Britt, Robert (March 14, 2003). Odyssey Spacecraft Generates New Mars Mysteries. Space. com. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
72. ^ Wardell, Jane (January 26, 2004). Europe's Beagle 2 Mars Probe Stays Ominously Silent. Space. com. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
73. ^ a b Bertaux et al. , Jean-Loup (June 9, 2005). Discovery of an aurora on Mars. Nature Magazine. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
74. ^ Mars Exploration Rovers- Science. NASA MER website. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
75. ^ Photo shows avalanche on Mars. CNN. Retrieved on 2008-03-04. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 51 - Nero, later to become Roman Emperor, is given the title Princeps iuventutis (head of the youth
76. ^ Mars Pulls Phoenix In. University of Arizona Phoenix mission Website. Retrieved on 2008-5-25.
77. ^ Phoenix: The Search for Water. NASA website. Retrieved on 2007-03-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1284 - Statute of Rhuddlan incorporated the Principality of Wales into England 1575 - Indian
78. ^ Mars Science Laboratory. NASA's MSL website. Retrieved on 2007-03-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1284 - Statute of Rhuddlan incorporated the Principality of Wales into England 1575 - Indian
79. ^ ExoMars. ESA website. Retrieved on 2007-03-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1284 - Statute of Rhuddlan incorporated the Principality of Wales into England 1575 - Indian
80. ^ Rincon, Paul (November 10, 2006). Events 1444 - Battle of Varna: The crusading forces of King Vladislaus III of Varna (aka Ulaszlo I of Hungary and Wladyslaw Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. European Mars launch pushed back. Retrieved on 2006-10-10. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 680 - Battle of Karbala: Shia Imam Husayn bin Ali, the grandson of the Prophet Muhammad, is decapitated
81. ^ MetNet Mars Mission
82. ^ MetNet Mars Precursor Mission
83. ^ Britt, Robert. When do we get to Mars?. Space. com FAQ: Bush's New Space Vision. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
84. ^ Liftoff for Aurora: Europe’s first steps to Mars, the Moon and beyond (October 11, 2002). Events 1138 - A massive earthquake struck Aleppo, Syria. 1531 - Huldrych Zwingli is killed See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. Retrieved on 2007-03-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1284 - Statute of Rhuddlan incorporated the Principality of Wales into England 1575 - Indian
85. ^ Yahoo.com, NASA aims to put man on Mars by 2037
86. ^ Deimos. Planetary Societies's Explore the Cosmos. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
87. ^ Mars Observing FAQ. Shallow Sky. Retrieved on 2006-06-15. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 763 BC - Assyrians record a Solar eclipse that will be used to fix the Chronology of Mesopotamian history
88. ^ Rao, Joe (August 22, 2003). Events 392 - Arbogast has Eugenius elected Western Roman Emperor. Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. NightSky Friday – Mars and Earth: The Top 10 Close Passes Since 3000 B.C.. Space. com. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
89. ^ Breyer, Stephen (March 1979). "Mutual Occultation of Planets". Sky and Telescope 57 #3: 220.
90. ^ Snyder, Dave (May 2001). An Observational History of Mars. Retrieved on 2007-02-26. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 747 BC - Epoch (origin of Ptolemy 's Nabonassar Era 364 - Valentinian I is proclaimed
91. ^ Zahnle K. (2001). "Decline and fall of the Martian empire". Nature (journal) 412: 209–213. Nature, in the broadest sense is equivalent to the natural world, physical universe, material world or material universe. doi:10.1038/35084148. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
92. ^ Salisbury F. B. (1962). "Martian Biology". Science (journal) 136 (3510): 17–26. Science is the Academic journal of the American Association for the Advancement of Science and is considered one of the world's most prestigious Scientific
93. ^ Google Mars. Retrieved on 2007-02-26. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 747 BC - Epoch (origin of Ptolemy 's Nabonassar Era 364 - Valentinian I is proclaimed
94. ^ Sheeham, William (February 2, 1997). Events 962 - Translatio imperii: Pope John XII crowns Otto I Holy Roman Emperor, the first Holy Roman Emperor Year 1997 ( MCMXCVII) was a Common year starting on Wednesday (link will display full 1997 Gregorian calendar Motions of Mars. The Planet Mars:: A History of Observation and Discovery. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
95. ^ Planet Symbols. NASA solar system exploration. Retrieved on 2006-06-13. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 1525 - Martin Luther marries Katharina von Bora, against the Celibacy rule decreed by the Roman Catholic Church for
96. ^ Percivel Lowell's Canals. Retrieved on 2007-03-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant
97. ^ Fergus, Charles (May 2004). "Mars Fever". Research/Penn State 24 (2).
98. ^ Tesla, Nikola (February 19, 1901). Talking with the Planets. Collier's Weekly. Retrieved on 2007-05-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1256 - The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV
99. ^ Cheney, Margaret (1981). Tesla, man out of time. Englewood Cliffs, New Jersey: Prentice-Hall, 162. ISBN 978-0-13-906859-1. OCLC 7672251. The OCLC Online Computer Library Center is according to its website a "nonprofit membership computer library service and research organization dedicated to the public purpose
100. ^ "Departure of Lord Kelvin", The New York Times, May 11, 1902, p. 29.
101. ^ a b Professor Pickering (January 16, 1901). The Light Flash From Mars (PDF). The New York Times. Archived from the original on 2007-05-20. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 325 - The First Council of Nicaea &ndash the first Ecumenical Council of the Christian Church is held Retrieved on 2007-05-20. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 325 - The First Council of Nicaea &ndash the first Ecumenical Council of the Christian Church is held
102. ^ Radio's War of the Worlds Broadcast (1938). Retrieved on 2007-03-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant
103. ^ Swift, Jonathan and the moons of Mars. David Darling. Retrieved on 2007-03-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant
104. ^ Kathy Miles and Charles F Peters II. Unmasking the Face. Retrieved on 2007-03-01. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 86 BC - Lucius Cornelius Sulla, at the head of a Roman Republic army enters in Athens, removing the Tyrant