A CD-ROM is a pre-pressed optical compact disc that contains data. Computers can read—but not write to or erase—CD-ROMs, i.e. it is a type of read-only memory. During the 1990s, CD-ROMs were popularly used to distribute software and data for computers and fourth generation video game consoles; some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer. The CD-ROM format was developed by Japanese company Denon in 1982, it was an extension of Compact Disc Digital Audio, adapted the format to hold any form of digital data, with a storage capacity of 553 MiB. CD-ROM was introduced by Denon and Sony at a Japanese computer show in 1984; the Yellow Book is the technical standard. One of a set of color-bound books that contain the technical specifications for all CD formats, the Yellow Book, standardized by Sony and Philips in 1983, specifies a format for discs with a maximum capacity of 650 MiB. CD-ROMs are identical in appearance to audio CDs, data are stored and retrieved in a similar manner.
Discs are made from a 1.2 mm thick disc of polycarbonate plastic, with a thin layer of aluminium to make a reflective surface. The most common size of CD-ROM is 120 mm in diameter, though the smaller Mini CD standard with an 80 mm diameter, as well as shaped compact discs in numerous non-standard sizes and molds, are available. Data is stored on the disc as a series of microscopic indentations. A laser is shone onto the reflective surface of the disc to read the pattern of lands; because the depth of the pits is one-quarter to one-sixth of the wavelength of the laser light used to read the disc, the reflected beam's phase is shifted in relation to the incoming beam, causing destructive interference and reducing the reflected beam's intensity. This is converted into binary data. Several formats are used for data stored on compact discs, known as the Rainbow Books; the Yellow Book, published in 1988, defines the specifications for CD-ROMs, standardized in 1989 as the ISO/IEC 10149 / ECMA-130 standard.
The CD-ROM standard builds on top of the original Red Book CD-DA standard for CD audio. Other standards, such as the White Book for Video CDs, further define formats based on the CD-ROM specifications; the Yellow Book itself is not available, but the standards with the corresponding content can be downloaded for free from ISO or ECMA. There are several standards that define how to structure data files on a CD-ROM. ISO 9660 defines the standard file system for a CD-ROM. ISO 13490 is an improvement on this standard which adds support for non-sequential write-once and re-writeable discs such as CD-R and CD-RW, as well as multiple sessions; the ISO 13346 standard was designed to address most of the shortcomings of ISO 9660, a subset of it evolved into the UDF format, adopted for DVDs. The bootable CD specification was issued in January 1995, to make a CD emulate a hard disk or floppy disk, is called El Torito. Data stored on CD-ROMs follows the standard CD data encoding techniques described in the Red Book specification.
This includes cross-interleaved Reed–Solomon coding, eight-to-fourteen modulation, the use of pits and lands for coding the bits into the physical surface of the CD. The structures used to group data on a CD-ROM are derived from the Red Book. Like audio CDs, a CD-ROM sector contains 2,352 bytes of user data, composed of 98 frames, each consisting of 33-bytes. Unlike audio CDs, the data stored in these sectors corresponds to any type of digital data, not audio samples encoded according to the audio CD specification. To structure and protect this data, the CD-ROM standard further defines two sector modes, Mode 1 and Mode 2, which describe two different layouts for the data inside a sector. A track inside a CD-ROM only contains sectors in the same mode, but if multiple tracks are present in a CD-ROM, each track can have its sectors in a different mode from the rest of the tracks, they can coexist with audio CD tracks as well, the case of mixed mode CDs. Both Mode 1 and 2 sectors use the first 16 bytes for header information, but differ in the remaining 2,336 bytes due to the use of error correction bytes.
Unlike an audio CD, a CD-ROM cannot rely on error concealment by interpolation. To achieve improved error correction and detection, Mode 1, used for digital data, adds a 32-bit cyclic redundancy check code for error detection, a third layer of Reed–Solomon error correction using a Reed-Solomon Product-like Code. Mode 1 therefore contains 288 bytes per sector for error detection and correction, leaving 2,048 bytes per sector available for data. Mode 2, more appropriate for image or video data, contains no additional error detection or correction bytes, having therefore 2,336 available data bytes per sector. Note that both modes, like audio CDs, still benefit from the lower layers of error correction at the frame level. Before being stored on a disc with the techniques described above, each CD-ROM sector is scrambled to prevent some problematic patterns from showing up; these scrambled sectors follow the same encoding process described in the Red Book in order to be stored
Nynorsk is one of the two written standards of the Norwegian language, the other being Bokmål. Nynorsk was established in 1929 as one of two state sanctioned fusions of Ivar Aasen's standard Norwegian language with the Dano-Norwegian written language, the other such fusion being called Bokmål. Nynorsk is a variation, closer to Landsmål, whereas Bokmål is closer to Riksmål. In local communities, one quarter of Norwegian municipalities have declared Nynorsk as their official language form, these municipalities account for about 12% of the Norwegian population. Nynorsk is being taught as a mandatory subject in both high school and elementary school for all Norwegians who don't have it as their own language form. Of the remaining municipalities that don't have Nynorsk as their official language form, half are neutral and half have adopted Bokmål as their official language form. Four of Norway's eighteen counties, Hordaland, Sogn og Fjordane and Møre og Romsdal, have Nynorsk as their official language form.
These four together comprise the region of Western Norway. Danish had been the written language of Norway until 1814, Danish with Norwegian intonation and pronunciation was on occasion spoken in the cities. With the independence of Norway from Denmark, Danish became a foreign language and thus lost much of its prestige, a conservative, written form of Norwegian, Landsmål, had been developed by 1850. By this time, the Danish language had been reformed into the written language Riksmål, no agreement was reached on which of the two forms to use. In 1885, the parliament declared the two forms equal. Efforts were made to fuse the two written forms into one language. A result was that Landsmål and Riksmål lost their official status in 1929, were replaced by the written forms Nynorsk and Bokmål, which were intended to be temporary intermediary stages before their final fusion into one hypothesised official Norwegian language known at the time as Samnorsk; this project was abandoned and Nynorsk and Bokmål remain the two sanctioned standards of what is today called the Norwegian language.
Both written languages are in reality fusions between the Norwegian and Danish languages as they were spoken and written around 1850, with Nynorsk closer to Norwegian and Bokmål closer to Danish. The official standard of Nynorsk has been altered during the process to create the common language form Samnorsk. A minor purist fraction of the Nynorsk population has stayed firm with the historical Aasen norm where these alterations of Nynorsk were rejected, known as Høgnorsk. Ivar Aasen-sambandet is an umbrella organization of associations and individuals promoting the use of Høgnorsk, whereas Noregs Mållag and Norsk Målungdom advocate the use of Nynorsk in general; the Landsmål language standard was constructed by the Norwegian linguist Ivar Aasen during the mid-19th century, to provide a Norwegian-based alternative to Danish, written, to some extent spoken, in Norway at the time. The word Nynorsk has another meaning. In addition to being the name of the present, official written language standard, Nynorsk can refer to the Norwegian language in use after Old Norwegian, 11th to 14th centuries, Middle Norwegian, 1350 to about 1550.
The written Norwegian, used until the period of Danish rule resembles Nynorsk. A major source of old written material is Diplomatarium Norvegicum in 22 printed volumes. In 1749, Erik Pontoppidan released a comprehensive dictionary of Norwegian words that were incomprehensible to Danish people, Glossarium Norvagicum Eller Forsøg paa en Samling Af saadanne rare Norske Ord Som gemeenlig ikke forstaaes af Danske Folk, Tilligemed en Fortegnelse paa Norske Mænds og Qvinders Navne, it is acknowledged that the first systematic study of the Norwegian language was made by Ivar Aasen in the mid 19th century. After the dissolution of Denmark–Norway and the establishment of the union between Sweden and Norway in 1814, Norwegians considered that neither Danish, by now a foreign language, nor by any means Swedish, were suitable written norms for Norwegian affairs; the linguist Knud Knudsen proposed a gradual Norwegianisation of Danish. Ivar Aasen, favoured a more radical approach, based on the principle that the spoken language of people living in the Norwegian countryside, who made up the vast majority of the population, should be regarded as more Norwegian than that of upper-middle class city-dwellers, who for centuries had been influenced by the Danish language and culture.
This idea was not unique to Aasen, can be seen in the wider context of Norwegian romantic nationalism. In the 1840s Aasen studied its dialects. In 1848 and 1850 he published the first Norwegian grammar and dictionary which described a standard that Aasen called Landsmål. New versions detailing the written standard were published in 1864 and 1873, in the 20th century by Olav Beito in 1970. During the same period, Venceslaus Ulricus Hammershaimb standardised the orthography of the Faroese language. Spoken Faroese is related to Landsmål and dialects in Norway proper, Lucas Debes and Peder Hansen Resen classified the Faroese tongue as Norwegian in the late 17th century. However, Faroese was established as a separate language. Aasen's work is based on the idea that Norwegian dialects had a common structure that made them a separate language alongside Danish and Swedish; the central point for Aasen therefore became to find and show the structural dependencies between the dialects. In order t
Hard science fiction
Hard science fiction is a category of science fiction characterized by concern for scientific accuracy and logic. The term was first used in print in 1957 by P. Schuyler Miller in a review of John W. Campbell's Islands of Space in the November issue of Astounding Science Fiction; the complementary term soft science fiction, formed by analogy to hard science fiction, first appeared in the late 1970s. The term is formed by analogy to the popular distinction between the "hard" and "soft" sciences. Science fiction critic Gary Westfahl argues. Stories revolving around scientific and technical consistency were written as early as the 1870s with the publication of Jules Verne's Twenty Thousand Leagues Under the Sea in 1870, among other stories; the attention to detail in Verne's work became an inspiration for many future scientists and explorers, although Verne himself denied writing as a scientist or predicting machines and technology of the future. Hugo Gernsback believed from the beginning of his involvement with science fiction in the 1920s that the stories should be instructive, although it was not long before he found it necessary to print fantastical and unscientific fiction in Amazing Stories to attract readers.
During Gernsback's long absence from SF publishing, from 1936 to 1953, the field evolved away from his focus on facts and education. The Golden Age of Science Fiction is considered to have started in the late 1930s and lasted until the mid-1940s, bringing with it "a quantum jump in quality the greatest in the history of the genre", according to science fiction historians Peter Nicholls and Mike Ashley. However, Gernsback's views were unchanged. In his editorial in the first issue of Science-Fiction Plus, he gave his view of the modern sf story: "the fairy tale brand, the weird or fantastic type of what mistakenly masquerades under the name of Science-Fiction today!" and he stated his preference for "truly scientific, prophetic Science-Fiction with the full accent on SCIENCE". In the same editorial, Gernsback called for patent reform to give science fiction authors the right to create patents for ideas without having patent models because many of their ideas predated the technical progress needed to develop specifications for their ideas.
The introduction referenced the numerous prescient technologies described throughout Ralph 124C 41+. The heart of the "hard SF" designation is the relationship of the science content and attitude to the rest of the narrative, the "hardness" or rigor of the science itself. One requirement for hard SF is procedural or intentional: a story should try to be accurate, logical and rigorous in its use of current scientific and technical knowledge about which technology, phenomena and situations that are and/or theoretically possible. For example, the development of concrete proposals for spaceships, space stations, space missions, a US space program in the 1950s and 1960s influenced a widespread proliferation of "hard" space stories. Discoveries do not invalidate the label of hard SF, as evidenced by P. Schuyler Miller, who called Arthur C. Clarke's 1961 novel A Fall of Moondust hard SF, the designation remains valid though a crucial plot element, the existence of deep pockets of "moondust" in lunar craters, is now known to be incorrect.
There is a degree of flexibility in how far from "real science" a story can stray before it leaves the realm of hard SF. HSF authors scrupulously avoid such technology as faster-than-light travel, while authors writing softer SF accept such notions Readers of "hard SF" try to find inaccuracies in stories. For example, a group at MIT concluded that the planet Mesklin in Hal Clement's 1953 novel Mission of Gravity would have had a sharp edge at the equator, a Florida high-school class calculated that in Larry Niven's 1970 novel Ringworld the topsoil would have slid into the seas in a few thousand years; the same book featured another inaccuracy: the eponymous Ringworld is not in a stable orbit and would crash into the sun without active stabilization. Niven fixed these errors in his sequel The Ringworld Engineers, noted them in the foreword. Films set in outer space that aspire to the hard SF label try to minimize the artistic liberties taken for the sake of practicality of effect. Factors include:.
How the film depicts sound despite the vacuum of space. Whether telecommunications are instant or are limited by the speed of light. Arranged chronologically by publication year. Hal Clement, "Uncommon Sense" James Blish, "Surface Tension", (Book 3 of The Seedling Stars Tom Godwin, "The Cold Equations" Isaac Asimov, "Evidence" Poul Anderson, "Kyrie" Frederik Pohl, "Day Million" Larry Niven, "Inconstant Moon" and "The Hole Man" and "Neutron Star" Greg Bear, "Tangents" Geoffrey A. Landis, "A Walk in the Sun" Vernor Vinge, "Fast Times at Fairmont High" Robert A. Heinlein, The Rolling Stones Hal Clement, Mission of Gravity Harry Martinson, Aniara John Wyndham, The Outward Urge Stanisław Lem, Solaris Arthur C. Clarke, A Fall of Moondust, 2001: A Space Odyssey, Rendezvous with Rama Michael Crichton, The Andromeda Strain Poul Anderson, Tau Zero James P. Hogan, The Two Faces of Tomorrow Robert L. Forward, Dragon's Egg Michael Crichton, Jurassic Park
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times. Earth's axis of rotation is tilted with respect to its orbital plane; the gravitational interaction between Earth and the Moon causes ocean tides, stabilizes Earth's orientation on its axis, slows its rotation. Earth is the largest of the four terrestrial planets. Earth's lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earth's surface is covered with water by oceans; the remaining 29% is land consisting of continents and islands that together have many lakes and other sources of water that contribute to the hydrosphere.
The majority of Earth's polar regions are covered in ice, including the Antarctic ice sheet and the sea ice of the Arctic ice pack. Earth's interior remains active with a solid iron inner core, a liquid outer core that generates the Earth's magnetic field, a convecting mantle that drives plate tectonics. Within the first billion years of Earth's history, life appeared in the oceans and began to affect the Earth's atmosphere and surface, leading to the proliferation of aerobic and anaerobic organisms; some geological evidence indicates. Since the combination of Earth's distance from the Sun, physical properties, geological history have allowed life to evolve and thrive. In the history of the Earth, biodiversity has gone through long periods of expansion punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely. Over 7.6 billion humans live on Earth and depend on its biosphere and natural resources for their survival.
Humans have developed diverse cultures. The modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most spelled eorðe, it has cognates in every Germanic language, their proto-Germanic root has been reconstructed as *erþō. In its earliest appearances, eorðe was being used to translate the many senses of Latin terra and Greek γῆ: the ground, its soil, dry land, the human world, the surface of the world, the globe itself; as with Terra and Gaia, Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus, Norse mythology included Jörð, a giantess given as the mother of Thor. Earth was written in lowercase, from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, the earth became the Earth when referenced along with other heavenly bodies. More the name is sometimes given as Earth, by analogy with the names of the other planets.
House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name but writes it in lowercase when preceded by the, it always appears in lowercase in colloquial expressions such as "what on earth are you doing?" The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago. By 4.54±0.04 Bya the primordial Earth had formed. The bodies in the Solar System evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, dust. According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 million years to form. A subject of research is the formation of some 4.53 Bya. A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth.
In this view, the mass of Theia was 10 percent of Earth, it hit Earth with a glancing blow and some of its mass merged with Earth. Between 4.1 and 3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth. Earth's atmosphere and oceans were formed by volcanic outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids and comets. In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity. By 3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind. A crust formed; the two models that explain land mass propose either a steady growth to the present-day forms or, more a rapid growth early in Earth history followed by a long-term steady continental area. Continents formed by plate tectonics
An electronic book known as an e-book or eBook, is a book publication made available in digital form, consisting of text, images, or both, readable on the flat-panel display of computers or other electronic devices. Although sometimes defined as "an electronic version of a printed book", some e-books exist without a printed equivalent. E-books can be read on dedicated e-reader devices, but on any computer device that features a controllable viewing screen, including desktop computers, laptops and smartphones. In the 2000s, there was a trend of print and e-book sales moving to the Internet, where readers buy traditional paper books and e-books on websites using e-commerce systems. With print books, readers are browsing through images of the covers of books on publisher or bookstore websites and selecting and ordering titles online. With e-books, users can browse through titles online, when they select and order titles, the e-book can be sent to them online or the user can download the e-book.
At the start of 2012 in the U. S. more e-books were published online. The main reasons for people buying e-books online are lower prices, increased comfort and a larger selection of titles. With e-books, "lectronic bookmarks make referencing easier, e-book readers may allow the user to annotate pages." "Although fiction and non-fiction books come in e-book formats, technical material is suited for e-book delivery because it can be searched" for keywords. In addition, for programming books, code examples can be copied; the amount of e-book reading is increasing in the U. S.. This is increasing, because by 2014 50% of American adults had an e-reader or a tablet, compared to 30% owning such devices in 2013. E-books are referred to as "ebooks", "eBooks", "Ebooks", "e-Books", "e-journals", "e-editions" or as "digital books"; the devices that are designed for reading e-books are called "e-readers", "ebook device" or "eReaders". Some trace the idea of an e-reader that would enable a reader to view books on a screen to a 1930 manifesto by Bob Brown, written after watching his first "talkie".
He titled it The Readies, playing off the idea of the "talkie". In his book, Brown says movies have outmaneuvered the book by creating the "talkies" and, as a result, reading should find a new medium: “A simple reading machine which I can carry or move around, attach to any old electric light plug and read hundred-thousand-word novels in 10 minutes if I want to, I want to.” Brown's notion, was much more focused on reforming orthography and vocabulary, than on medium: introducing huge numbers of portmanteau symbols to replace normal words, punctuation to simulate action or movement. E-readers never followed a model at all like Brown's. Brown predicted the miniaturization and portability of e-readers. In an article, Jennifer Schuessler writes, "The machine, Brown argued, would allow readers to adjust the type size, avoid paper cuts and save trees, all while hastening the day when words could be'recorded directly on the palpitating ether.'" He felt the e-reader should bring a new life to reading.
Schuessler relates it to a DJ spinning bits of old songs to create a beat or an new song as opposed to just a remix of a familiar song. The inventor of the first e-book is not agreed upon; some notable candidates include the following: In 1949, Ángela Ruiz Robles, a teacher from Ferrol, patented the Enciclopedia Mecánica, or the Mechanical Encyclopedia, a mechanical device which operated on compressed air where text and graphics were contained on spools that users would load onto rotating spindles. Her idea was to create a device which would decrease the number of books that her pupils carried to school; the final device would include audio recordings, a magnifying glass, a calculator and an electric light for night reading. Her device was never put into production but one of her prototypes is kept in the National Museum of Science and Technology in La Coruna, Spain; the first e-book may be the Index Thomisticus, a annotated electronic index to the works of Thomas Aquinas, prepared by Roberto Busa, S.
J. beginning in 1949 and completed in the 1970s. Although stored on a single computer, a distributable CD-ROM version appeared in 1989. However, this work is sometimes omitted. In 2005, the Index was published online. Alternatively, some historians consider electronic books to have started in the early 1960s, with the NLS project headed by Doug Engelbart at Stanford Research Institute, the Hypertext Editing System and FRESS projects headed by Andries van Dam at Brown University. FRESS documents were structure-oriented rather than line-oriented. All these systems provided extensive hyperlinking and other capabilities. Van Dam is thought to have coined the term "electronic book", it was established enough to use in an article title by 1985. FRESS was used for reading extensive primary texts on
The Galactic Center, or Galactic Centre, is the rotational center of the Milky Way. It is 8,122 ± 31 parsecs away from Earth in the direction of the constellations Sagittarius and Scorpius where the Milky Way appears brightest, it coincides with the compact radio source Sagittarius A*. There are around 10 million stars within one parsec of the Galactic Center, dominated by red giants, with a significant population of massive supergiants and Wolf-Rayet stars from a star formation event around one million years ago, one supermassive black hole of 4.100 ± 0.034 million solar masses at the Galactic Center, which powers the Sagittarius A* radio source. Because of interstellar dust along the line of sight, the Galactic Center cannot be studied at visible, ultraviolet, or soft X-ray wavelengths; the available information about the Galactic Center comes from observations at gamma ray, hard X-ray, infrared and radio wavelengths. Immanuel Kant stated in General Natural History and Theory of the Heavens that a large star was at the center of the Milky Way Galaxy, that Sirius might be the star.
Harlow Shapley stated in 1918 that the halo of globular clusters surrounding the Milky Way seemed to be centered on the star swarms in the constellation of Sagittarius, but the dark molecular clouds in the area blocked the view for optical astronomy. In the early 1940s Walter Baade at Mount Wilson Observatory took advantage of wartime blackout conditions in nearby Los Angeles to conduct a search for the center with the 100-inch Hooker Telescope, he found that near the star Alnasl there is a one-degree-wide void in the interstellar dust lanes, which provides a clear view of the swarms of stars around the nucleus of our Milky Way Galaxy. This gap has been known as Baade's Window since. At Dover Heights in Sydney, Australia, a team of radio astronomers from the Division of Radiophysics at the CSIRO, led by Joseph Lade Pawsey, used'sea interferometry' to discover some of the first interstellar and intergalactic radio sources, including Taurus A, Virgo A and Centaurus A. By 1954 they had built an 80-foot fixed dish antenna and used it to make a detailed study of an extended powerful belt of radio emission, detected in Sagittarius.
They named an intense point-source near the center of this belt Sagittarius A, realised that it was located at the center of our Galaxy, despite being some 32 degrees south-west of the conjectured galactic center of the time. In 1958 the International Astronomical Union decided to adopt the position of Sagittarius A as the true zero co-ordinate point for the system of galactic latitude and longitude. In the equatorial coordinate system the location is: RA 17h 45m 40.04s, Dec −29° 00′ 28.1″. The exact distance between the Solar System and the Galactic Center is not certain, although estimates since 2000 have remained within the range 24–28.4 kilolight-years. The latest estimates from geometric-based methods and standard candles yield the following distances to the Galactic Center: 7.4±0.2 ± 0.2 or 7.4±0.3 kpc 7.62±0.32 kpc 7.7±0.7 kpc 7.94 or 8.0±0.5 kpc 7.98±0.15 ± 0.20 or 8.0±0.25 kpc 8.33±0.35 kpc 8.7±0.5 kpc An accurate determination of the distance to the Galactic Center as established from variable stars or standard candles is hindered by countless effects, which include: an ambiguous reddening law.
The nature of the Milky Way's bar, which extends across the Galactic Center, is actively debated, with estimates for its half-length and orientation spanning between 1–5 kpc and 10–50°. Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other; the bar is delineated by red-clump stars. The bar may be surrounded by a ring called the 5-kpc ring that contains a large fraction of the molecular hydrogen present in the Milky Way, most of the Milky Way's star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way; the complex astronomical radio source Sagittarius A appears to be located exactly at the Galactic Center, contains an intense compact radio source, Sagittarius A*, which coincides with a supermassive black hole at the center of the Milky Way. Accretion of gas onto the black hole involving an accretion disk around it, would release energy to power the radio source, itself much larger than the black hole.
The latter is too small to see with present instruments. A study in 2008 which linked radio telescopes in Hawaii and California measured the diameter of Sagittarius A* to be 44 million kilometers. For comparison, the radius of Earth's orbit around the Sun is about 150 million kilometers, whereas the distance of Mercury from the Sun at closest approach is 46 million kilometers. Thus, the diameter of the radio source is less than the distance from Mercury to the Sun. Scientists at the Max Planck Institute for Extraterrestrial Physics in Germany using Chilean telescopes have confirmed the existence of a superm
Brad Templeton is a software architect, civil rights advocate, entrepreneur. He graduated from the University of Waterloo. Templeton is considered one of the early luminaries of Usenet, in 1989 founded ClariNet Communications Corporation, which used Usenet protocols to distribute news articles, one of the first commercial examples of electronic publishing. In his "Net History in Brief" post, he coined, he founded Looking Glass Software, was involved in the development of a number of software packages. In 1979, he developed a version of Time Trek for the Commodore PET, he was the chairman of the board of the Electronic Frontier Foundation for ten years until February 2010, when he relinquished his tenure to John Buckman. Templeton remains on the board of the EFF, he created the Usenet newsgroup rec.humor.funny in 1987 and moderated it from 1987 to 1992. To Commodore users, he's best known for POWER and the assembler PAL. Templeton is known in the Internet and legal community for writing about political and social issues related to computing and networks.
One of the most frequently-cited works on Internet copyright law is his 10 Big Myths of Copyright Explained. Templeton serves on the advisory council of Represent. Us, a nonpartisan anti-corruption organization. Templeton is the son of Charles Templeton and Sylvia Murphy, the brother of Ty Templeton. Brad Templeton's home page