1.
Andrees Allgemeiner Handatlas
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Andrees Allgemeiner Handatlas was a major cartographic work published in several German and foreign editions 1881 -1937. It was named after Richard Andree and published by Velhagen & Klasing, Bielefeld and Leipzig, the 1937 edition of Andrees Handatlas was printed using offset printing. The first edition appeared in 1881, the 4th and 5th editions were edited by Albert Scobel, the 6th through 8th editions, by Ernst Ambrosius, and the final edition, by Konrad Frenzel. Editions for other countries were issued, Österreichisch-Ungarischer editions were published in Vienna in 1904,1909,1910,1911,1912 and 1913. Three editions of Andrees Stora Handatlas were published in Stockholm, with maps of Scandinavia. The verso text and the material was in Swedish. The maps of Andrees atlas were used for Cassells Universal Atlas, which was published in London in 1891-1893 using maps printed in Leipzig in English, editions of a Geographisches Handbuch for Andrees Handatlas were issued in 1882,1894,1895, 1898-1899,1902 and 1909. Other well-known titles of Velhagen & Klasing were Putzgers Historischer Schulatlas, Grosser Volksatlas, founded 1835, the firm was taken over by F. Cornelsen in 1954, and is now fully merged into that company
2.
Planet
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The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye and these were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, in 2006, the International Astronomical Union officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of mass based on where or what they orbit. The planets were thought by Ptolemy to orbit Earth in deferent, at about the same time, by careful analysis of pre-telescopic observation data collected by Tycho Brahe, Johannes Kepler found the planets orbits were not circular but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the planets share characteristics such as volcanism, hurricanes, tectonics. Planets are generally divided into two types, large low-density giant planets, and smaller rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System, in order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites, several thousands of planets around other stars have been discovered in the Milky Way. e. in the habitable zone. On December 20,2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star, Kepler-20. A2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the Milky Way, around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone. The idea of planets has evolved over its history, from the lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include not only in the Solar System. The ambiguities inherent in defining planets have led to much scientific controversy, the five classical planets, being visible to the naked eye, have been known since ancient times and have had a significant impact on mythology, religious cosmology, and ancient astronomy. In ancient times, astronomers noted how certain lights moved across the sky, as opposed to the fixed stars, ancient Greeks called these lights πλάνητες ἀστέρες or simply πλανῆται, from which todays word planet was derived. In ancient Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the Universe and that all the planets circled Earth. The first civilization known to have a theory of the planets were the Babylonians
3.
Natural satellite
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A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet. In the Solar System there are six planetary satellite systems containing 178 known natural satellites, four IAU-listed dwarf planets are also known to have natural satellites, Pluto, Haumea, Makemake, and Eris. As of January 2012, over 200 minor-planet moons have been discovered, the Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of Earth is much greater than that of any other natural-satellite–planet ratio in the Solar System. At 3,474 km across, Earths Moon is 0.27 times the diameter of Earth, the first known natural satellite was the Moon, but it was considered a planet until Copernicus introduction of heliocentrism in 1543. Until the discovery of the Galilean satellites in 1610, however, galileo chose to refer to his discoveries as Planetæ, but later discoverers chose other terms to distinguish them from the objects they orbited. The first to use of the satellite to describe orbiting bodies was the German astronomer Johannes Kepler in his pamphlet Narratio de Observatis a se quatuor Iouis satellitibus erronibus in 1610. He derived the term from the Latin word satelles, meaning guard, attendant, or companion, the term satellite thus became the normal one for referring to an object orbiting a planet, as it avoided the ambiguity of moon. In 1957, however, the launching of the artificial object Sputnik created a need for new terminology, to further avoid ambiguity, the convention is to capitalize the word Moon when referring to Earths natural satellite, but not when referring to other natural satellites. A few recent authors define moon as a satellite of a planet or minor planet, there is no established lower limit on what is considered a moon. Small asteroid moons, such as Dactyl, have also been called moonlets, the upper limit is also vague. Two orbiting bodies are described as a double body rather than primary. Asteroids such as 90 Antiope are considered double asteroids, but they have not forced a clear definition of what constitutes a moon, some authors consider the Pluto–Charon system to be a double planet. In contrast, irregular satellites are thought to be captured asteroids possibly further fragmented by collisions, most of the major natural satellites of the Solar System have regular orbits, while most of the small natural satellites have irregular orbits. The Moon and possibly Charon are exceptions among large bodies in that they are thought to have originated by the collision of two large proto-planetary objects. The material that would have placed in orbit around the central body is predicted to have reaccreted to form one or more orbiting natural satellites. As opposed to planetary-sized bodies, asteroid moons are thought to form by this process. Triton is another exception, although large and in a close, circular orbit, its motion is retrograde, most regular moons in the Solar System are tidally locked to their respective primaries, meaning that the same side of the natural satellite always faces its planet. The only known exception is Saturns natural satellite Hyperion, which rotates chaotically because of the influence of Titan
4.
Telescope
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A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation. The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s and they found use in both terrestrial applications and astronomy. Within a few decades, the telescope was invented, which used mirrors to collect. In the 20th century many new types of telescopes were invented, including radio telescopes in the 1930s, the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galileis instruments presented at a banquet at the Accademia dei Lincei, in the Starry Messenger, Galileo had used the term perspicillum. The earliest recorded working telescopes were the telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals, Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, Galileo heard about the Dutch telescope in June 1609, built his own within a month, and improved upon the design in the following year. Also in 1609, Thomas Harriot became the first person known to point a telescope skyward in order to make observations of a celestial object. The idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs, in 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector. The invention of the lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter. The largest reflecting telescopes currently have objectives larger than 10 m, the 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937, since then, a tremendous variety of complex astronomical instruments have been developed. The name telescope covers a range of instruments. Most detect electromagnetic radiation, but there are differences in how astronomers must go about collecting light in different frequency bands. The near-infrared can be collected much like light, however in the far-infrared and submillimetre range. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm to 2000 μm, on the other hand, the Spitzer Space Telescope, observing from about 3 μm to 180 μm uses a mirror. Also using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the range from about 0.2 μm to 1.7 μm
5.
Moon
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The Moon is an astronomical body that orbits planet Earth, being Earths only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, following Jupiters satellite Io, the Moon is second-densest satellite among those whose densities are known. The average distance of the Moon from the Earth is 384,400 km, the Moon is thought to have formed about 4.51 billion years ago, not long after Earth. It is the second-brightest regularly visible celestial object in Earths sky, after the Sun and its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its cycle of phases have made the Moon an important cultural influence since ancient times on language, calendars, art. The Moons gravitational influence produces the ocean tides, body tides, and this matching of apparent visual size will not continue in the far future. The Moons linear distance from Earth is currently increasing at a rate of 3.82 ±0.07 centimetres per year, since the Apollo 17 mission in 1972, the Moon has been visited only by uncrewed spacecraft. The usual English proper name for Earths natural satellite is the Moon, the noun moon is derived from moone, which developed from mone, which is derived from Old English mōna, which ultimately stems from Proto-Germanic *mǣnōn, like all Germanic language cognates. Occasionally, the name Luna is used, in literature, especially science fiction, Luna is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of our moon. The principal modern English adjective pertaining to the Moon is lunar, a less common adjective is selenic, derived from the Ancient Greek Selene, from which is derived the prefix seleno-. Both the Greek Selene and the Roman goddess Diana were alternatively called Cynthia, the names Luna, Cynthia, and Selene are reflected in terminology for lunar orbits in words such as apolune, pericynthion, and selenocentric. The name Diana is connected to dies meaning day, several mechanisms have been proposed for the Moons formation 4.51 billion years ago, and some 60 million years after the origin of the Solar System. These hypotheses also cannot account for the angular momentum of the Earth–Moon system. This hypothesis, although not perfect, perhaps best explains the evidence, eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, and Jeff Taylor challenged fellow lunar scientists, You have eighteen months. Go back to your Apollo data, go back to computer, do whatever you have to. Dont come to our conference unless you have something to say about the Moons birth, at the 1984 conference at Kona, Hawaii, the giant impact hypothesis emerged as the most popular. Afterward there were only two groups, the giant impact camp and the agnostics. Giant impacts are thought to have been common in the early Solar System, computer simulations of a giant impact have produced results that are consistent with the mass of the lunar core and the present angular momentum of the Earth–Moon system
6.
Mars
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Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is referred to as the Red Planet because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet, Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan, there are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers, liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 6⁄1000 that of the Earths, except at the lowest elevations for short periods. The two polar ice caps appear to be largely of water. The volume of ice in the south polar ice cap, if melted. On November 22,2016, NASA reported finding a large amount of ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior, Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, optical ground-based telescopes are typically limited to resolving features about 300 kilometers across when Earth and Mars are closest because of Earths atmosphere. Mars is approximately half the diameter of Earth with an area only slightly less than the total area of Earths dry land. Mars is less dense than Earth, having about 15% of Earths volume and 11% of Earths mass, the red-orange appearance of the Martian surface is caused by iron oxide, or rust. It can look like butterscotch, other common colors include golden, brown, tan. Like Earth, Mars has differentiated into a metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ±65 kilometers, consisting primarily of iron and this iron sulfide core is thought to be twice as rich in lighter elements than Earths. The core is surrounded by a mantle that formed many of the tectonic and volcanic features on the planet
7.
International Astronomical Union
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The International Astronomical Union is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the recognized authority for assigning designations to celestial bodies. The IAU is a member of the International Council for Science and its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU maintains friendly relations with organizations that include amateur astronomers in their membership, the IAU has its head office on the second floor of the Institut dAstrophysique de Paris in the 14th arrondissement of Paris. The IAU is also responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams, the Minor Planet Center also operates under the IAU, and is a clearinghouse for all non-planetary or non-moon bodies in the Solar System. The Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers, the IAU was founded on July 28,1919, at the Constitutive Assembly of the International Research Council held in Brussels, Belgium. The 7 initial member states were Belgium, Canada, France, Great Britain, Greece, Japan, the first executive committee consisted of Benjamin Baillaud, Alfred Fowler, and four vice presidents, William Campbell, Frank Dyson, Georges Lecointe, and Annibale Riccò. Thirty-two Commissions were appointed at the Brussels meeting and focused on topics ranging from relativity to minor planets, the reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, May 2–10,1922. By the end of the first General Assembly, ten nations had joined the Union. Although the Union was officially formed eight months after the end of World War I, the first 50 years of the Unions history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents, twelve of the fourteen past General Secretaries in the period 1964-2006 contributed their recollections of the Unions history in IAU Information Bulletin No.100. Six past IAU Presidents in the period 1976–2003 also contributed their recollections in IAU Information Bulletin No.104, the IAU includes a total of 12,664 individual members who are professional astronomers from 96 countries worldwide. 83% of all members are male, while 17% are female, among them the unions current president. Membership also includes 79 national members, professional astronomical communities representing their countrys affiliation with the IAU, the sovereign body of the IAU is its General Assembly, which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union, the right to vote on matters brought before the Assembly varies according to the type of business under discussion. On budget matters, votes are weighted according to the subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid, an absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union, since 1922, the IAU General Assembly meets every three years, with the exception of the period between 1938 and 1948, due to World War II
8.
Image resolution
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Image resolution is the detail an image holds. The term applies to digital images, film images. Higher resolution means more image detail, image resolution can be measured in various ways. Resolution quantifies how close lines can be to other and still be visibly resolved. Resolution units can be tied to physical sizes, to the size of a picture. Line pairs are used instead of lines, a line pair comprises a dark line. A line is either a line or a light line. A resolution of 10 lines per millimeter means 5 dark lines alternating with 5 light lines, photographic lens and film resolution are most often quoted in line pairs per millimeter. The resolution of digital cameras can be described in different ways. Resolution is the capability of the sensor to observe or measure the smallest object clearly with distinct boundaries, there is a difference between the resolution and a pixel. A pixel is actually a unit of the digital Resolution depends upon the size of the pixel, usually, with any given lens setting, the smaller the size of the pixel, the higher the resolution will be and the clearer the object in the image will be. Images having smaller pixel sizes might consist of more pixels, the number of pixels correlates to the amount of information within the image. An image of N pixels height by M pixels wide can have any less than N lines per picture height. Other conventions include describing pixels per unit or pixels per area unit. None of these pixel resolutions are true resolutions, but they are referred to as such. Below is an illustration of how the image might appear at different pixel resolutions. An image that is 2048 pixels in width and 1536 pixels in height has a total of 2048×1536 =3,145,728 pixels or 3.1 megapixels, one could refer to it as 2048 by 1536 or a 3. 1-megapixel image. Or, you can think of it as a low quality image if printed at about 28.5 inches wide
9.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
10.
Cartography
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Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively, the fundamental problems of traditional cartography are to, Set the maps agenda and select traits of the object to be mapped. This is the concern of map editing, traits may be physical, such as roads or land masses, or may be abstract, such as toponyms or political boundaries. Represent the terrain of the object on flat media. This is the concern of map projections, eliminate characteristics of the mapped object that are not relevant to the maps purpose. This is the concern of generalization, reduce the complexity of the characteristics that will be mapped. This is also the concern of generalization, orchestrate the elements of the map to best convey its message to its audience. This is the concern of map design, modern cartography constitutes many theoretical and practical foundations of geographic information systems. The earliest known map is a matter of debate, both because the term map isnt well-defined and because some artifacts that might be maps might actually be something else. A wall painting that might depict the ancient Anatolian city of Çatalhöyük has been dated to the late 7th millennium BCE, the oldest surviving world maps are from 9th century BCE Babylonia. One shows Babylon on the Euphrates, surrounded by Assyria, Urartu and several cities, all, in turn, another depicts Babylon as being north of the world center. The ancient Greeks and Romans created maps since Anaximander in the 6th century BCE, in the 2nd century AD, Ptolemy wrote his treatise on cartography, Geographia. This contained Ptolemys world map – the world known to Western society. As early as the 8th century, Arab scholars were translating the works of the Greek geographers into Arabic, in ancient China, geographical literature dates to the 5th century BCE. The oldest extant Chinese maps come from the State of Qin, dated back to the 4th century BCE, in the book of the Xin Yi Xiang Fa Yao, published in 1092 by the Chinese scientist Su Song, a star map on the equidistant cylindrical projection. Early forms of cartography of India included depictions of the pole star and these charts may have been used for navigation. Mappa mundi are the Medieval European maps of the world, approximately 1,100 mappae mundi are known to have survived from the Middle Ages. Of these, some 900 are found illustrating manuscripts and the remainder exist as stand-alone documents, the Arab geographer Muhammad al-Idrisi produced his medieval atlas Tabula Rogeriana in 1154
11.
Diacritical marks
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A diacritic – also diacritical mark, diacritical point, or diacritical sign – is a glyph added to a letter, or basic glyph. The term derives from the Ancient Greek διακριτικός, from διακρίνω, diacritic is primarily an adjective, though sometimes used as a noun, whereas diacritical is only ever an adjective. Some diacritical marks, such as the acute and grave, are often called accents, diacritical marks may appear above or below a letter, or in some other position such as within the letter or between two letters. The main use of marks in the Latin script is to change the sound-values of the letters to which they are added. In other Latin alphabets, they may distinguish between homonyms, such as the French là versus la that are both pronounced /la/, in Gaelic type, a dot over a consonant indicates lenition of the consonant in question. In other alphabetic systems, diacritical marks may perform other functions, vowel pointing systems, namely the Arabic harakat and the Hebrew niqqud systems, indicate vowels that are not conveyed by the basic alphabet. The Indic virama and the Arabic sukūn mark the absence of a vowel, in the Hanyu Pinyin official romanization system for Chinese, diacritics are used to mark the tones of the syllables in which the marked vowels occur. In orthography and collation, a letter modified by a diacritic may be treated either as a new and this varies from language to language, and may vary from case to case within a language. ◌ː – triangular colon, used in the IPA to mark long vowels, not all diacritics occur adjacent to the letter they modify. In the Wali language of Ghana, for example, an apostrophe indicates a change of vowel quality, because of vowel harmony, all vowels in a word are affected, so the scope of the diacritic is the entire word. In abugida scripts, like those used to write Hindi and Thai, diacritics indicate vowels, the tittle on the letter i of the Latin alphabet originated as a diacritic to clearly distinguish i from the minims of adjacent letters. It first appeared in the 11th century in the sequence ii, then spread to i adjacent to m, n, u, the j, originally a variant of i, inherited the tittle. The shape of the diacritic developed from initially resembling todays acute accent to a flourish by the 15th century. With the advent of Roman type it was reduced to the round dot we have today, tanwīn symbols, Serve a grammatical role in Arabic. The sign ـً is most commonly written in combination with alif, waṣla, Comes most commonly at the beginning of a word. Indicates a type of hamza that is pronounced only when the letter is read at the beginning of the talk, ḥarakāt, fatḥa kasra ḍamma sukūn The ḥarakāt or vowel points serve two purposes, They serve as a phonetic guide. They indicate the presence of short vowels or their absence, at the last letter of a word, the vowel point reflects the inflection case or conjugation mood. For nouns, The ḍamma is for the nominative, fatḥa for the accusative, for verbs, the ḍamma is for the imperfective, fatḥa for the perfective, and the sukūn is for verbs in the imperative or jussive moods
12.
Wikipedia
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Wikipedia is a free online encyclopedia that aims to allow anyone to edit articles. Wikipedia is the largest and most popular reference work on the Internet and is ranked among the ten most popular websites. Wikipedia is owned by the nonprofit Wikimedia Foundation, Wikipedia was launched on January 15,2001, by Jimmy Wales and Larry Sanger. Sanger coined its name, a portmanteau of wiki and encyclopedia, There was only the English language version initially, but it quickly developed similar versions in other languages, which differ in content and in editing practices. With 5,377,348 articles, the English Wikipedia is the largest of the more than 290 Wikipedia encyclopedias, in 2005, Nature published a peer review comparing 42 science articles from Encyclopædia Britannica and Wikipedia, and found that Wikipedias level of accuracy approached Encyclopædia Britannicas. Other collaborative online encyclopedias were attempted before Wikipedia, but none were so successful, Wikipedia began as a complementary project for Nupedia, a free online English-language encyclopedia project whose articles were written by experts and reviewed under a formal process. Nupedia was founded on March 9,2000, under the ownership of Bomis and its main figures were Jimmy Wales, the CEO of Bomis, and Larry Sanger, editor-in-chief for Nupedia and later Wikipedia. Nupedia was licensed initially under its own Nupedia Open Content License, while Wales is credited with defining the goal of making a publicly editable encyclopedia, Sanger is credited with the strategy of using a wiki to reach that goal. On January 10,2001, Sanger proposed on the Nupedia mailing list to create a wiki as a project for Nupedia. Wikipedia was launched on January 15,2001, as a single English-language edition at www. wikipedia. com, Wikipedias policy of neutral point-of-view was codified in its first months. Otherwise, there were few rules initially and Wikipedia operated independently of Nupedia. Originally, Bomis intended to make Wikipedia a business for profit, Wikipedia gained early contributors from Nupedia, Slashdot postings, and web search engine indexing. By August 8,2001, Wikipedia had over 8,000 articles, on September 25,2001, Wikipedia had over 13,000 articles. By the end of 2001, it had grown to approximately 20,000 articles and 18 language editions and it had reached 26 language editions by late 2002,46 by the end of 2003, and 161 by the final days of 2004. Nupedia and Wikipedia coexisted until the servers were taken down permanently in 2003. Citing fears of commercial advertising and lack of control in Wikipedia and these moves encouraged Wales to announce that Wikipedia would not display advertisements, and to change Wikipedias domain from wikipedia. com to wikipedia. org. Around 1,800 articles were added daily to the encyclopedia in 2006, a team at the Palo Alto Research Center attributed this slowing of growth to the projects increasing exclusivity and resistance to change. Others suggest that the growth is flattening naturally because articles that could be called low-hanging fruit—topics that clearly merit an article—have already been created, the Wall Street Journal cited the array of rules applied to editing and disputes related to such content among the reasons for this trend
13.
Io (moon)
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Io /ˈaɪ. oʊ/ is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons and it was discovered in 1610 and was named after the mythological character Io, a priestess of Hera who became one of Zeuss lovers. With over 400 active volcanoes, Io is the most geologically active object in the Solar System, several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km above the surface. Ios surface is dotted with more than 100 mountains that have been uplifted by extensive compression at the base of Ios silicate crust. Some of these peaks are taller than Mount Everest, unlike most satellites in the outer Solar System, which are mostly composed of water ice, Io is primarily composed of silicate rock surrounding a molten iron or iron-sulfide core. Most of Ios surface is composed of extensive plains coated with sulfur, Ios volcanism is responsible for many of its unique features. Numerous extensive lava flows, several more than 500 km in length, the materials produced by this volcanism make up Ios thin, patchy atmosphere and Jupiters extensive magnetosphere. Ios volcanic ejecta also produce a large torus around Jupiter. Io played a significant role in the development of astronomy in the 17th and 18th centuries and it was discovered in January 1610 by Galileo Galilei, along with the other Galilean satellites. This discovery furthered the adoption of the Copernican model of the Solar System, the development of Keplers laws of motion, and the first measurement of the speed of light. In 1979, the two Voyager spacecraft revealed Io to be a geologically active world, with numerous volcanic features, large mountains, the Galileo spacecraft performed several close flybys in the 1990s and early 2000s, obtaining data about Ios interior structure and surface composition. These spacecraft also revealed the relationship between Io and Jupiters magnetosphere and the existence of a belt of high-energy radiation centered on Ios orbit, Io receives about 3,600 rem of ionizing radiation per day. Further observations have made by Cassini–Huygens in 2000 and New Horizons in 2007, as well as from Earth-based telescopes. From the surface of Io, Jupiter would subtend an arc of 19. 5°, although Simon Marius is not credited with the sole discovery of the Galilean satellites, his names for the moons were adopted. Based on a suggestion from Johannes Kepler in October 1613, he devised a naming scheme whereby each moon was named for a lover of the Greek mythological Zeus or his Roman equivalent. He named the innermost large moon of Jupiter after the Greek mythological figure Io, since the surface was first seen up close by Voyager 1, the International Astronomical Union has approved 225 names for Ios volcanoes, mountains, plateaus, and large albedo features. The approved feature categories used for Io for different types of volcanic features include patera, fluctus, vallis, named mountains, plateaus, layered terrain, and shield volcanoes include the terms mons, mensa, planum, and tholus, respectively. Named, bright albedo regions use the term regio, examples of named features are Prometheus, Pan Mensa, Tvashtar Paterae, and Tsũi Goab Fluctus
14.
Triton (moon)
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Triton is the largest natural satellite of the planet Neptune. It was discovered on October 10,1846, by English astronomer William Lassell and it is the only large moon in the Solar System with a retrograde orbit, an orbit in the opposite direction to its planets rotation. At 2,700 kilometres in diameter, it is the seventh-largest moon in the Solar System, because of its retrograde orbit and composition similar to Plutos, Triton is thought to have been a dwarf planet captured from the Kuiper belt. Triton has a surface of frozen nitrogen, a mostly water-ice crust, an icy mantle. The core makes up two-thirds of its total mass, Triton has a mean density of 2.061 g/cm3 and is composed of approximately 15–35% water ice. Triton is one of the few moons in the Solar System known to be geologically active, as a consequence, its surface is relatively young with sparse impact craters, and a complex geological history revealed in intricate cryovolcanic and tectonic terrains. Part of its surface has geysers erupting sublimated nitrogen gas, contributing to a nitrogen atmosphere less than 1/70,000 the pressure of Earths atmosphere at sea level. Triton was discovered by British astronomer William Lassell on October 10,1846, a brewer by trade, Lassell began making mirrors for his amateur telescope in 1820. When John Herschel received news of Neptunes discovery, he wrote to Lassell suggesting he search for possible moons, Lassell did so and discovered Triton eight days later. Lassell also claimed to have discovered rings, although Neptune was later confirmed to have rings, they are so faint and dark that it is doubtful that he actually saw them. Triton is named after the Greek sea god Triton, the son of Poseidon, the name was first proposed by Camille Flammarion in his 1880 book Astronomie Populaire, and was officially adopted many decades later. Until the discovery of the second moon Nereid in 1949, Triton was commonly referred to as the satellite of Neptune. Lassell did not name his own discovery, he successfully suggested the name Hyperion, previously chosen by John Herschel. Triton is unique among all large moons in the Solar System for its orbit around its planet. Most of the irregular moons of Jupiter and Saturn also have retrograde orbits. However, these moons are all much more distant from their primaries, and are small in comparison, Tritons orbit is associated with two tilts, the inclination of Neptunes spin to Neptunes orbit, 30°, and the inclination of Tritons orbit to Neptunes spin, 157°. Tritons orbit precesses forward relative to Neptunes spin with a period of about 678 Earth years and that inclination is currently 130°, Tritons orbit is now near its maximum departure from coplanarity with Neptunes. Tritons rotation is locked to be synchronous with its orbit around Neptune
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Venus
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Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period of any planet in the Solar System and it is named after the Roman goddess of love and beauty. It is the second-brightest natural object in the sky after the Moon, reaching an apparent magnitude of −4.6. Because Venus orbits within Earths orbit it is a planet and never appears to venture far from the Sun. Venus is a planet and is sometimes called Earths sister planet because of their similar size, mass, proximity to the Sun. It is radically different from Earth in other respects and it has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the surface is 92 times that of Earth. Venus is by far the hottest planet in the Solar System, with a surface temperature of 735 K. Venus is shrouded by an layer of highly reflective clouds of sulfuric acid. It may have had water oceans in the past, but these would have vaporized as the temperature rose due to a greenhouse effect. The water has probably photodissociated, and the hydrogen has been swept into interplanetary space by the solar wind because of the lack of a planetary magnetic field. Venuss surface is a dry desertscape interspersed with rocks and is periodically resurfaced by volcanism. As one of the brightest objects in the sky, Venus has been a fixture in human culture for as long as records have existed. It has been sacred to gods of many cultures, and has been a prime inspiration for writers and poets as the morning star. Venus was the first planet to have its motions plotted across the sky, as the closest planet to Earth, Venus has been a prime target for early interplanetary exploration. It was the first planet beyond Earth visited by a spacecraft, Venuss thick clouds render observation of its surface impossible in visible light, and the first detailed maps did not emerge until the arrival of the Magellan orbiter in 1991. Plans have been proposed for rovers or more missions. Venus is one of the four planets in the Solar System
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Crater chain
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A crater chain is a line of craters along the surface of an astronomical body. The descriptor term for crater chains is catena, as specified by the International Astronomical Unions rules on planetary nomenclature. Many examples of such chains are thought to have formed by the impact of a body that was broken up by tidal forces into a string of smaller objects following roughly the same orbit. An example of such a tidally disrupted body that was observed prior to its impact on Jupiter is Comet Shoemaker-Levy 9, during the Voyager observations of the Jupiter system, planetary scientists identified 13 crater chains on Callisto and three on Ganymede. Later some of these turned out to be secondary or tectonic features. As of 1996,8 primary chains on Callisto and 3 on Ganymede were confirmed, other cases, such as many of those on Mars, represent chains of collapse pits associated with grabens
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Enki Catena
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Enki Catena is a crater chain on Ganymede measuring 161.3 kilometres long. This chain of 13 craters probably formed by a comet which was pulled into pieces by Jupiters gravity as it passed too close to the planet, soon after this breakup, the 13 fragments crashed onto Ganymede in rapid succession. The Enki craters formed across the boundary between areas of bright terrain and dark terrain, delimited by a thin trough running diagonally across the center of this image. The ejecta deposit surrounding the craters appears very bright on the bright terrain, even though all the craters formed nearly simultaneously, it is difficult to discern any ejecta deposit on the dark terrain. This may be because the impacts excavated and mixed dark material into the ejecta and the resulting mix is not apparent against the dark background
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Chaos terrain
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In astrogeology, chaos terrain is a planetary surface area where features such as ridges, cracks, and plains appear jumbled and enmeshed with one another. Chaos terrain is a feature of the planets Mars and Mercury, Jupiters moon Europa. In scientific nomenclature, chaos is used as a component of proper nouns, on April 1,2010, NASA released the first images under the HiWish program in which citizens suggested places for HiRISE to photograph. One of the eight locations was Aureum Chaos, the first image below gives a wide view of the area. The next two images are from the HiRISE image, the specific causes of chaos terrain are not yet well understood. A number of different astrogeological forces have offered as causes of chaos terrain. On Europa, impact events and subsequent penetration into a ductile or liquid crust were suggested in 2004 and these lakes would be entirely encased in the moons icy outer shell and distinct from a liquid ocean thought to exist farther down beneath the ice shell. Rather than an impact, the authors propose a four-step model for producing the surface expressions. Full confirmation of the lakes existence will require a space designed to probe the ice shell either physically or indirectly. On Mars chaos terrain is believed to be associated with the release of huge amounts of water, the Chaotic features may have collapsed when water came out of the surface. Martian rivers begin with a Chaos region, a chaotic region can be recognized by a rats nest of mesas, buttes, and hills, chopped through with valleys which in places look almost patterned. Some parts of this area have not collapsed completely—they are still formed into large mesas. Chaotic terrain occurs in numerous locations on Mars, and always gives the impression that something abruptly disturbed the ground. By counting craters and by studying the valleys relations with other geological features, scientists have thought of different ideas for the cause of chaotic terrain. One explanation for the source of the water that left the ground. Later, when the ocean disappeared, the sediments froze, if hot magma came near to the region, the ice would have melted and formed large underground river systems. When these neared the surface, huge amounts would break out of the ground, there is much evidence for an ocean on Mars. Places have been photographed that could be where the ground collapsed when water left an subterranean rivers to flow out of chaotic regions, one of the first theories for the source of the water was based on old Viking Orbiter pictures
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Iani Chaos
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Iani Chaos is a region of chaos terrain at the south end of the outflow channel Ares Vallis, of the Margaritifer Sinus quadrangle region of the planet Mars, centered at approximately ~342°E, 2°S. This is the region of Ares Vallis. The chaotic terrain is believed to have formed via the removal of subsurface water or ice, resulting in flooding at the surface. Several sites in the Margaritifer Sinus quadrangle have been proposed as areas to send NASAs next major Mars rover, among the top 33 landing sites was Iani Chaos. A picture below shows a potential landing zone in Iani Chaos, deposits of hematite and gypsum have been found there. Those minerals are formed in connection with water. The aim of the Mars Science Laboratory is to search for signs of ancient life and it is hoped that a later mission could then return samples from sites identified as probably containing remains of life. To safely bring the craft down, a 12-mile-wide, smooth, geologists hope to examine places where water once ponded. They would like to examine sediment layers, aram Chaos Ares Vallis Chaos terrain List of areas of chaos terrain on Mars Mars Outflow channels
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Chasma
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In planetary geology, a chasma is a deep, elongated, steep-sided depression. As of January 2013, the IAU has named 118 such features in the Solar System, on Venus, Mars, Saturns satellites Mimas, Tethys, Dione and Rhea, an example is Eos Chasma on Mars. Below are images of some of the major chasmata of Mars, the map shows their relative locations. Parts of the floor of Candor Chasma contains layered deposits that have been termed interior layered deposits and these layers may have formed when the whole area was a giant lake. Some places on Mars contain hydrated sulfate deposits, sulfate formation involves the presence of water. The European Space Agencys Mars Express found evidence of perhaps epsomite and kieserite, scientists want to visit these areas with robotic rovers. Images of rocks in the walls almost always show layers. Some layers appear tougher than others, in the image below of Ganges Chasma Layers, as seen by HiRISE, one can see that the upper, light-toned deposits are eroding much faster than the lower darker layers. Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces, an example of hard layers is shown below in the picture of layers in the canyon wall in Coprates, as seen by Mars Global Surveyor. It is likely the rock strata in the preserve a long geological history of Mars. Dark layers may be due to lava flows. The dark volcanic basalt is common on Mars. However, light-toned deposits may have resulted from rivers, lakes, volcanic ash, the Mars Rovers found light-toned rocks to contain sulfates. Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life, hebes Chasma, a large enclosed valley, may have once held water. Hydrated minerals have been found there and it is thought that large-scale underground springs of groundwater at different times burst to the surface to form deposits called Light Toned Deposits. Some suggest present or fossilized life forms may be there because the deposits are relatively young
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Eos Chasma
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Eos Chasma is a chasma in the southern part of the Valles Marineris canyon system of the Margaritifer Sinus quadrangle region of the planet Mars. Eos Chasma’s western floor is composed of an etched massive material composed of either volcanic or eolian deposits later eroded by the Martian wind. The eastern end of the Eos chasma has an area of streamlined bars. This is interpreted to be stream-carved plateau deposits and material transported and deposited by flowing fluid, ganges Chasma is an offshoot of Eos Chasma. MRO discovered sulfate, hydrated sulfate, and iron oxides in Eos Chasma, according to an analysis by Vicky Hamilton of the University of Hawaii, Eos Chasma may be the source of the ALH84001 meteorite, which some believe to be evidence of past life on Mars. However, the analysis was not conclusive, in part because it was limited to parts of Mars not obscured by dust, geography of Mars Eos Chasma on Google Mars - scrollable map centered on Eos Chasma Eos Chasma - photos by the European Space Agencys Mars Express
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Collis (planetary nomenclature)
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Collis is a small hill or knob on a celestial body. The term is used in planetary nomenclature, it is a part of proper names of such features. Like other generic terms, it is capitalized and stands after the proper name, as of 2015, only groups of the hills have names, and the term is used only in plural. Like the other terms of nomenclature, this word describes only external view of the features. So, it is used for hills of any origin, names of bigger uplands usually contain the term Tholus, and the names of still bigger mountains – the term Mons. Peculiar round mountains, which are found on Venus, get names with the term Farrum, the term Collis was introduced into planetary nomenclature in 1982, on XVIIIth General Assembly of International Astronomical Union. This year two groups of hills on Mars were named, as of May 2015,43 such groups are named,22 on Mars,16 on Venus and 5 on Titan
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Corona (planetary geology)
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In planetary geology, a corona is an oval-shaped feature. Coronae appear on both the planet Venus and Uranuss moon Miranda and may be formed by upwellings of warm material below the surface, on Venus, coronae are large, crown-like, volcanic features. The largest corona on Venus is the Artemis Corona, which is 2100 km in diameter, the small Uranian moon Miranda sports ovoid features that are very large in relation to its size. They may be formed by diapirs, upwellings of warm ice
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Miranda (moon)
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Miranda or Uranus V is the smallest and innermost of Uranuss five round satellites. Like the other moons of Uranus, Miranda orbits close to its planets equatorial plane. Because Uranus orbits the Sun on its side, Mirandas orbit is perpendicular to the ecliptic, at just 470 km in diameter, Miranda is one of the smallest objects in the Solar System known to be in hydrostatic equilibrium —only Saturns moon Mimas is smaller. The origin and evolution of this varied geology, the most of any Uranian satellite, are not fully understood. Miranda was discovered by Gerard Kuiper on 16 February 1948 at McDonald Observatory, the only close-up images of Miranda are from the Voyager 2 probe, which made observations of Miranda during its Uranus flyby in January 1986. During the flyby, Mirandas southern hemisphere pointed towards the Sun, Miranda was discovered on 16 February 1948 by planetary astronomer Gerard Kuiper using the McDonald Observatorys 82-inch Otto Struve Telescope. Its motion around Uranus was confirmed on 1 March 1948 and it was the first satellite of Uranus discovered in nearly 100 years. However, the moons had been named specifically after fairies. Subsequently discovered satellites of Uranus were named after Shakespearean characters, whether fairies or not, of Uranuss five round satellites, Miranda orbits closest to it, at roughly 129,000 km from the surface, about a quarter again as far as its most distant ring. Its orbital period is 34 hours, and, like that of the Moon, is synchronous with its period, which means it always shows the same face to Uranus. Mirandas orbital inclination is high for a body so close to its planet. At 1.2 g/cm3, Miranda is the least dense of Uranuss round satellites and that density suggests a composition of more than 60% water ice. Mirandas surface may be water ice, with the low-density body also probably containing silicate rock. Mirandas surface has patchwork regions of broken terrain indicating intense geological activity in Mirandas past and it also has the largest known cliff in the Solar System, Verona Rupes, which has a height of over 5 km. Some of Mirandas terrain is less than 100 million years old based on crater counts. It is believed through computer modelling that Miranda may have an additional corona on the unimaged hemisphere, the ridges probably represent extensional tilt blocks. The canyons probably represent graben formed by extensional faulting, other features may be due to cryovolcanic eruptions of icy magma. Mirandas past geological activity is believed to have driven by tidal heating during the time when it was in orbital resonance with Umbriel
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Impact crater
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An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims, Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. Where such processes have destroyed most of the original crater topography and this indicates that there should be far more relatively young craters on the planet than have been discovered so far. Note that the rate of impact cratering in the outer Solar System could be different from the inner Solar System, although Earths active surface processes quickly destroy the impact record, about 190 terrestrial impact craters have been identified. They are also found in the stable interior regions of continents. Impact craters are not to be confused with landforms that may appear similar, including calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others. Daniel Barringer was one of the first to identify an impact crater, Meteor Crater in Arizona, in the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the United States. He concluded they had created by some great explosive event. However, in 1936, the geologists John D, albritton Jr. revisited Buchers studies and concluded that the craters that he studied were probably formed by impacts. The concept of impact cratering remained more or less speculative until the 1960s, armed with the knowledge of shock-metamorphic features, Carlyle S. By 1970, they had identified more than 50. Although their work was controversial, the American Apollo Moon landings, because the processes of erosion on the Moon are minimal, craters persist almost indefinitely. Since the Earth could be expected to have roughly the same cratering rate as the Moon, Impact cratering involves high velocity collisions between solid objects, typically much greater than the velocity of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the effects of travel through the atmosphere. The fastest impacts occur at about 72 km/s in the worst case scenario in which an object in a retrograde near-parabolic orbit hits Earth, the median impact velocity on Earth is about 20 km/s. The larger the meteoroid the more of its initial cosmic velocity it preserves, while an object of 9,000 kg maintains about 6% of its original velocity, one of 900,000 kg already preserves about 70%. Extremely large bodies are not slowed by the atmosphere at all, impacts at these high speeds produce shock waves in solid materials, and both impactor and the material impacted are rapidly compressed to high density
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Wrinkle ridge
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A wrinkle ridge is a type of feature commonly found on lunar maria. These features are low, sinuous ridges formed on the surface that can extend for up to several hundred kilometers. Wrinkle ridges are features created when the basaltic lava cooled and contracted. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare and they are sometimes called veins due to their resemblance to the veins that protrude from beneath the skin. Wrinkle ridges are named with the Latin designation dorsum, the standard IAU nomenclature uses the names of people to identify wrinkle ridges on the Moon. Thus the Dorsa Burnet are named for Thomas Burnet, and the Dorsum Owen is named after George Owen of Henllys, although several hypotheses have been advanced as causes of Martian wrinkle ridges, today they are generally considered to be of tectonic origin. They are evidence of compressional stresses in Mars’ crust, the stress created a crack where one side was pushed on top of the other side, also known as a thrust fault. List of features on the Moon Planetary nomenclature Golombek, M. P. F. S. Anderson, and M. T. Zuber, Martian wrinkle ridge topography, Evidence for subsurface faults from MOLA, J. Geophys. Montési, L. G. J. and M. T. Zuber, Clues to the structure of Mars from wrinkle ridge sets and localization instability. Watters, T. R. Wrinkle Ridge Assemblages on the Terrestrial Planets, Evidence of Recent Thrust Faulting on the Moon Revealed by the Lunar Reconnaissance Orbiter Camera
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Volcanology of Io
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Volcanology of Io, a moon of Jupiter, is the scientific study of lava flows, volcanic pits, and volcanism on the surface of Io. Its volcanic activity was discovered in 1979 by Voyager 1 imaging scientist Linda Morabito, observations of Io by passing spacecraft and Earth-based astronomers have revealed more than 150 active volcanoes. Up to 400 such volcanoes are predicted to exist based on these observations, Ios volcanism makes the satellite one of only four known currently volcanically active worlds in the Solar System. First predicted shortly before the Voyager 1 flyby, the source for Ios volcanism comes from tidal heating produced by its forced orbital eccentricity. This differs from Earths internal heating, which is derived primarily from radioactive isotope decay, Ios eccentric orbit leads to a slight difference in Jupiters gravitational pull on the satellite between its closest and farthest points on its orbit, causing a varying tidal bulge. This variation in the shape of Io causes frictional heating in its interior, without this tidal heating, Io might have been similar to the Moon, a world of similar size and mass, geologically dead and covered with numerous impact craters. Ios volcanism has led to the formation of hundreds of centres and extensive lava formations. Three different types of eruptions have been identified, differing in duration, intensity, lava effusion rate. Lava flows on Io, tens or hundreds of long, have primarily basaltic composition. Although most of the lava on Io is made of basalt, in addition, eruption temperatures as high as 1,600 K were detected, which can be explained by the eruption of high-temperature ultramafic silicate lavas. This material paints the surrounding terrain in red, black, and/or white, spacecraft that have flown by Io since 1979 have observed numerous surface changes as a result of Ios volcanic activity. Before the Voyager 1 encounter with Io on March 5,1979, the discovery of a cloud of sodium surrounding Io led to theories that the satellite would be covered in evaporites. Hints of discoveries to come arose from Earth-based infrared observations taken in the 1970s, an anomalously high thermal flux, compared to the other Galilean satellites, was discovered during measurements taken at an infrared wavelength of 10 μm while Io was in Jupiters shadow. At the time, this flux was attributed to the surface having a much higher thermal inertia than Europa. These results were different from measurements taken at wavelengths of 20 μm. A sharp increase in Ios thermal emission at 5 μm was observed on February 20,1978 by Witteborn, et al. They based this prediction on models of Ios interior that took into account the amount of heat produced by the varying tidal pull of Jupiter on Io caused by its slightly eccentric orbit. Their calculations suggested that the amount of heat generated for an Io with a homogeneous interior would be three times greater than the amount of heat generated by radioactive isotope decay alone and this effect would be even greater with a differentiated Io
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Facula
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For the genus of gossamer-winged butterflies, see Facula. A facula /ˈfækjʊlə/, Latin for little torch, is literally a bright spot, the term has several common technical uses. It is used in planetary nomenclature for naming certain surface features of planets and moons, faculae are produced by concentrations of magnetic field lines. Strong concentrations of faculae appear in activity, with or without sunspots. The faculae and the sunspots contribute noticeably to variations in the Solar constant, the chromospheric counterpart of a facular region is called a plage. Cererian faculae are thought to suggest current or past outgassing on Ceres, perhaps due to volcanism or cometary activity
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Titan (moon)
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Titan is the largest moon of Saturn. It is the only known to have a dense atmosphere. Titan is the sixth ellipsoidal moon from Saturn, frequently described as a planet-like moon, Titan is 50% larger than Earths Moon, and it is 80% more massive. It is the second-largest moon in the Solar System, after Jupiters moon Ganymede, and is larger than the smallest planet, Mercury, discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn, and the sixth known planetary satellite. Titan orbits Saturn at 20 Saturn radii, from Titans surface, Saturn subtends an arc of 5.09 degrees and would appear 11.4 times larger in the sky than the Moon from Earth. Titan is primarily composed of ice and rocky material. The geologically young surface is smooth, with few impact craters, although mountains. The atmosphere of Titan is largely nitrogen, minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. The climate—including wind and rain—creates surface features similar to those of Earth, such as dunes, rivers, lakes, seas, and deltas, Huygens was inspired by Galileos discovery of Jupiters four largest moons in 1610 and his improvements in telescope technology. Christiaan, with the help of his brother Constantijn Huygens, Jr. began building telescopes around 1650 and it was the sixth moon to be discovered. He named it Saturni Luna, publishing in the 1655 tract De Saturni Luna Observatio Nova, after Giovanni Domenico Cassini published his discoveries of four more moons of Saturn between 1673 and 1686, astronomers fell into the habit of referring to these and Titan as Saturn I through V. Other early epithets for Titan include Saturns ordinary satellite, Titan is officially numbered Saturn VI because after the 1789 discoveries the numbering scheme was frozen to avoid causing any more confusion. Numerous small moons have been discovered closer to Saturn since then and he suggested the names of the mythological Titans, brothers and sisters of Cronus, the Greek Saturn. In Greek mythology, the Titans were a race of powerful deities, descendants of Gaia and Uranus, Titan orbits Saturn once every 15 days and 22 hours. Because of this, there is a point on its surface. Longitudes on Titan are measured westward, starting from the passing through this point. Its orbital eccentricity is 0.0288, and the plane is inclined 0.348 degrees relative to the Saturnian equator. Viewed from Earth, Titan reaches a distance of about 20 Saturn radii from Saturn
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Fossa (geology)
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In planetary geology, a fossa is a long, narrow depression on the surface of an extraterrestrial body, such as a planet or moon. Fossae are believed to be the result of a number of geological processes, many fossae on Mars are probably graben. The Tharsis quadrangle is home to large troughs called fossae in the language used for Mars. This term is derived from Latin, therefore fossa is singular, troughs form when the crust is stretched until it breaks. The stretching can be due to the weight of a nearby volcano. Studies have shown that the volcanoes of Tharsis caused most of the major fossae on Mars, the stress that caused the fossae and other tectonic features is centered in Noctis Labyrinthus, at 4 S and 253 E. But the center has moved somewhat over time, fossae/pit craters are common near volcanoes in the Tharsis and Elysium system of volcanoes. A trough often has two breaks with a middle section moving down, leaving steep cliffs along the sides, such a trough is called a graben, lake George, in northern New York State, is a lake that sits in a graben. Sometimes, a line of pits form as material collapse into a void that results from the stretching, pit craters do not have rims or ejecta around them, like impact craters do. Studies have found that on Mars a fault may be as deep as 5 km, moreover, the crack or fault sometimes widens or dilates. This widening causes a void to form with a high volume. When material slides into the void, a pit crater or a pit crater chain forms, on Mars, individual pit craters can join to form chains or even to form troughs that are sometimes scalloped. Other ideas have been suggested for the formation of fossae and pit craters, there is evidence that they are associated with dikes of magma. Magma might move along, under the surface, breaking the rock, the resulting action would cause a crack to form at the surface. Dikes caused both by tectonic stretching and by dikes are found in Iceland, pit craters are not common on Earth. Sinkholes, where the falls into a hole resemble pit craters on Mars. However, on the Earth these holes are caused by limestone being dissolved thereby causing a void, knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be reservoirs of water. Fossae on Mars Fossae on Venus Fossae on the Moon Fossae on Enceladus Fossae on Ganymede
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Apollo program
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Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six spaceflights, twelve men walked on the Moon, Apollo ran from 1961 to 1972, with the first manned flight in 1968. It achieved its goal of manned lunar landing, despite the setback of a 1967 Apollo 1 cabin fire that killed the entire crew during a prelaunch test. After the first landing, sufficient flight hardware remained for nine follow-on landings with a plan for extended lunar geological and astrophysical exploration, Budget cuts forced the cancellation of three of these. The crew returned to Earth safely by using the Lunar Module as a lifeboat for these functions, Apollo set several major human spaceflight milestones. It stands alone in sending manned missions beyond low Earth orbit, Apollo 8 was the first manned spacecraft to orbit another celestial body, while the final Apollo 17 mission marked the sixth Moon landing and the ninth manned mission beyond low Earth orbit. The program returned 842 pounds of rocks and soil to Earth, greatly contributing to the understanding of the Moons composition. The program laid the foundation for NASAs subsequent human spaceflight capability, Apollo also spurred advances in many areas of technology incidental to rocketry and manned spaceflight, including avionics, telecommunications, and computers. The Apollo program was conceived during the Eisenhower administration in early 1960, while the Mercury capsule could only support one astronaut on a limited Earth orbital mission, Apollo would carry three astronauts. Possible missions included ferrying crews to a station, circumlunar flights. The program was named after the Greek god of light, music, and the sun by NASA manager Abe Silverstein, who later said that I was naming the spacecraft like Id name my baby. Silverstein chose the name at home one evening, early in 1960, in July 1960, NASA Deputy Administrator Hugh L. Dryden announced the Apollo program to industry representatives at a series of Space Task Group conferences. Preliminary specifications were laid out for a spacecraft with a mission module cabin separate from the module. On August 30, a feasibility study competition was announced, and on October 25, meanwhile, NASA performed its own in-house spacecraft design studies led by Maxime Faget, to serve as a gauge to judge and monitor the three industry designs. In November 1960, John F. Kennedy was elected president after a campaign that promised American superiority over the Soviet Union in the fields of space exploration and missile defense. Beyond military power, Kennedy used aerospace technology as a symbol of prestige, pledging to make the US not first but, first and, first if. Despite Kennedys rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became president and he knew little about the technical details of the space program, and was put off by the massive financial commitment required by a manned Moon landing. On April 12,1961, Soviet cosmonaut Yuri Gagarin became the first person to fly in space, Kennedy was circumspect in his response to the news, refusing to make a commitment on Americas response to the Soviets
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Europa (moon)
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Europa /jʊˈroʊpə/, is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet. It is also the sixth-largest moon in the Solar System, Europa was discovered in 1610 by Galileo Galilei and was named after Europa, the legendary mother of King Minos of Crete and lover of Zeus. Slightly smaller than Earths Moon, Europa is primarily made of rock and has a water-ice crust. It has an atmosphere composed primarily of oxygen. Its surface is striated by cracks and streaks, whereas craters are relatively rare, in addition to Earth-bound telescope observations, Europa has been examined by a succession of space probe flybys, the first occurring in the early 1970s. Europa has the smoothest surface of any solid object in the Solar System. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, sea salt from a subsurface ocean may be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable, in addition, the Hubble Space Telescope detected water vapor plumes similar to those observed on Saturns moon Enceladus, which are thought to be caused by erupting cryogeysers. The Galileo mission, launched in 1989, provides the bulk of current data on Europa, no spacecraft has yet landed on Europa, although there have been several proposed exploration missions. The European Space Agencys Jupiter Icy Moon Explorer is a mission to Ganymede that is due to launch in 2022, NASAs planned Europa Multiple-Flyby Mission will be launched in the mid-2020s. Europa, along with Jupiters three other large moons, Io, Ganymede, and Callisto, was discovered by Galileo Galilei on 8 January 1610, and possibly independently by Simon Marius. The first reported observation of Io and Europa was made by Galileo Galilei on 7 January 1610 using a 20×-magnification refracting telescope at the University of Padua. However, in observation, Galileo could not separate Io and Europa due to the low magnification of his telescope. The following day,8 January 1610, Io and Europa were seen for the first time as separate bodies during Galileos observations of the Jupiter system, Europa is named after Europa, daughter of the king of Tyre, a Phoenician noblewoman in Greek mythology. Like all the Galilean satellites, Europa is named after a lover of Zeus, Europa was courted by Zeus and became the queen of Crete. The naming scheme was suggested by Simon Marius, who discovered the four satellites independently, Marius attributed the proposal to Johannes Kepler. The names fell out of favor for a time and were not revived in general use until the mid-20th century. In much of the astronomical literature, Europa is simply referred to by its Roman numeral designation as Jupiter II or as the second satellite of Jupiter
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Macula (planetary geology)
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Macula is the Latin word for spot. It is used in planetary nomenclature to refer to dark areas on the surface of a planet or moon. They are seen on the icy surfaces of Pluto, Jupiters moon Europa, Saturns moon Titan, Neptunes moon Triton, the term was adopted for planetary nomenclature when high resolution pictures of Europa revealed unusual new surface features. Lists of named maculae, on Europa, on Titan, on Triton
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Lunar mare
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The lunar maria /ˈmɑːriə/ are large, dark, basaltic plains on Earths Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for seas, by astronomers who mistook them for actual seas. They are less reflective than the highlands as a result of their iron-rich compositions, the maria cover about 16 percent of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are smaller, residing mostly in very large craters. The traditional nomenclature for the Moon also includes one oceanus, as well as features with the names lacus, palus, the last three are smaller than maria, but have the same nature and characteristics. The names of maria generally refer to states of mind, with a few exceptions, for example, Mare Humboldtianum and Mare Smythii were established long before the nomenclature was accepted and do not follow this pattern. The ages of the mare basalts have been determined both by direct radiometric dating and by the technique of crater counting, the few basaltic eruptions that occurred on the far side are old, whereas the youngest flows are found within Oceanus Procellarum on the nearside. While many of the basalts either erupted within, or flowed into, low-lying impact basins, there are many common misconceptions concerning the spatial distribution of mare basalts. Since many mare basalts fill low-lying impact basins, it was assumed that the impact event itself somehow caused the volcanic eruption. It is sometimes suggested that the gravity field of the Earth might preferentially allow eruptions to occur on the near side, but not far side. However, in a frame rotating with the Moon, the centrifugal acceleration the moon is experiencing is exactly equal. There is thus no net force directed towards the Earth, the Earth tides do act to deform the shape of the Moon, but this shape is one of an elongated ellipsoid with high points at both the sub- and anti-Earth points. As an analogy, one should remember that there are two high tides per day on Earth, and not one, since mare basaltic magmas are denser than upper crustal anorthositic materials, basaltic eruptions might be favored at locations of low elevation where the crust is thin. However, the far side South Pole-Aitken basin contains the lowest elevations of the Moon and is yet only modestly filled by basaltic lavas, in addition, the crustal thickness beneath this basin is predicted to be much smaller than beneath Oceanus Procellarum. It is commonly suggested that there is form of link between the synchronous rotation of the Moon about the Earth, and the mare basalts. However, gravitational torques that result in tidal despinning only arise from the moments of inertia of the body, furthermore, tidal despinning is predicted to have occurred quickly, whereas the majority of mare basalts erupted about one billion years later. The reason that the basalts are predominantly located on the near-side hemisphere of the Moon is still being debated by the scientific community. In this low-impact collision, the moon was crushed into the surface of the moon
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Ligeia Mare
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Ligeia Mare /laɪˈdʒiːə ˈmɑːriː/ is a lake in the north polar region of Titan, the planet Saturns largest moon. It is the second largest known body of liquid on Titan, larger than Lake Superior on Earth, it is mostly composed of liquid methane, with unknown but lesser components of dissolved nitrogen and ethane, as well as other organic compounds. It is located at 78° N, 249° W, and has been imaged by the Cassini spacecraft. Measuring roughly 420 km by 350 km across, it has an area of about 126,000 km2. The lake may be connected to the larger Kraken Mare. Its namesake is Ligeia, one of the sirens in Greek mythology, Ligeia Mare has two predominant types of coastline, crenulated and subdued. The former is characterized by hummocky, eroded terrain, the latter by lower, smoother topography, crenulated terrain predominates on the eastern and southern sides of the lake, subdued terrain to the west and north. Except in the southeast where the topography extends to the coast. The coast has numerous bays that appear to be flooded river mouths,2013 radar measurements by Cassini indicate parts of the lake are 170 m deep which implies the liquid must be very pure methane since the radar signal was able to pass right through it. The surface of the lake appears very smooth on radar, it is flat within a few millimeters, the average depth is on the order of 50 m, while the maximum depth is probably >200 m. The total volume is likely to be > 7000 km3, the reasons for Ligeia Mares nearly pure methane composition are still not entirely clear. Theories include it migrating into the undersea crust or perhaps into Kraken Mare, in the latter case, ethane-poor liquid hydrocarbon would be the equivalent of terrestrial freshwater. In addition to ethane, Titans atmosphere produces a range of more complex photochemical products, such as nitriles. These are believed to precipitate out and flow into Titans seas, radar data suggests that Ligeia Mares seabed is likely covered in a thick layer of these organic compounds. Temperature readings from the shoreline of Ligeia Mare suggest that it is porous, however, transient phenomena have been observed including a 260 square kilometre feature dubbed Magic Island by Cassini scientists. The Titan Lake In-situ Sampling Propelled Explorer is a lander mission which is envisioned to splash down. A similar concept, albeit without its own system, was the Titan Mare Explorer. A lake-lander mission planned to splash down on and then drift about the lake, labelled map of the liquid bodies in the north polar region of Titan
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Mesa
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Mesa is the American English term for tableland, an elevated area of land with a flat top and sides that are usually steep cliffs. It takes its name from its characteristic table-top shape and it may also be called a table hill, table-topped hill or table mountain. It is larger than a butte, which it resembles closely. Examples are also found in other nations including Spain, Sardinia, North and South Africa, Arabia, India. Grand Mesa is a mesa located in western Colorado in the Southwest United States. Cerro Negro is a mesa in Argentina, the term mesa is used throughout the United States to describe a flat-topped mountain or hill. Mesas form by weathering and erosion of layered rocks that have been uplifted by tectonic activity. This process is called differential erosion, the most resistant rock types include sandstone, conglomerate, quartzite, basalt, chert, limestone, lava flows and sills. Lava flows and sills, in particular, are resistant to weathering and erosion. The less resistant rock layers are made up of shale. The differences in strength of rock layers is what gives mesas their distinctive shape. Less resistant rocks are eroded away on the surface into valleys, a large area of very resistant rock, such as a sill may shield the layers below it from erosion while the softer rock surrounding it is eroded into valleys, thus forming a caprock. Differences in rock type also reflect on the sides of a mesa, as instead of smooth slopes, the more resistant layers form the cliffs, or stairsteps, while the less resistant layers form gentle slopes, or benches, between the cliffs. Cliffs retreat and are cut off from the main cliff, or plateau. When the cliff edge does not retreat uniformly, but instead is indented by headward eroding streams, as the underlying shale erodes away, it can no longer support the overlying cliff layers, which collapse and retreat. When the caprock has caved away to the point where only a little remains, a transitional zone on Mars, known as the fretted terrain, lies between highly cratered highlands and less cratered lowlands. The younger lowland exhibits steep walled mesas and knobs, the mesa and knobs are separated by flat lying lowlands. They are thought to form from ice-facilitated mass wasting processes from ground or atmospheric sources, the mesas and knobs decrease in size with increasing distance from the highland escarpment
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Mons (planetary nomenclature)
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Mons is a mountain on a celestial body. The term is used in planetary nomenclature, it is a part of the names of such features. It is capitalized and usually stands after the given name. The term tholus is used for names of smaller uplands, peculiar round mountains found on Venus get names with the term farrum. The term mons, like other terms of nomenclature, describes only the external view of the feature. It is used for mountains of any origin, and objects in this class are very diverse, usually they are results of tectonic, impact or volcanic processes. Examples of such mountains are the Maxwell Montes on Venus, the Montes Apenninus on the Moon and Olympus Mons on Mars, more unusual origins are also possible. For example, the Geryon Montes of Mars are a remnant of a former plateau within Ius Chasma. During impact events, mountains can appear not only on the border of the resulting crater, the term mons was firstly used for extraterrestrial mountains by Michael van Langren in 1645. He assigned names to some mountains on the Moon, but none of these remain in use. Two years later Johannes Hevelius proposed the first names of extraterrestrial mountains still used, the lunar Alps and Apennines still bear names given by Hevelius, and five of his other mountain names nowadays refer to other features. The International Astronomical Union approved the first names of mountains in 1935, although without a generic Latin term. As of May 2015,262 extraterrestrial mountains and mountain systems have official names,117 on Venus,50 on Mars,48 on the Moon,23 on Io,13 on Titan,9 on Iapetus,1 on Mercury and 1 on Tethys. Media related to Extraterrestrial mountains at Wikimedia Commons
The above article incorporates text from the United States Geological Survey Gazetteer of Planetary Nomenclature, which is in the public domain.
The above article incorporates text from the United States Geological Survey