Agloe is a fictional hamlet in Colchester, Delaware County, New York, that became an actual landmark after mapmakers made up the community as a phantom settlement, an example of a "copyright trap" and similar to a trap street. Agloe was put onto the map in order to catch plagiarism as it appears only on their map and not on any others. Soon, using fictional "copyright traps" became a typical strategy in mapmaker design to thwart plagiarism. Agloe was known as a "paper town" because of this.
- "Agloe, New York" | 2015-10-03 | 101 Upvotes 17 Comments
The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.
The first table of haversines in English was published by James Andrew in 1805, but Florian Cajori credits an earlier use by José de Mendoza y Ríos in 1801. The term haversine was coined in 1835 by James Inman.
These names follow from the fact that they are customarily written in terms of the haversine function, given by hav(θ) = sin2(θ/2). The formulas could equally be written in terms of any multiple of the haversine, such as the older versine function (twice the haversine). Prior to the advent of computers, the elimination of division and multiplication by factors of two proved convenient enough that tables of haversine values and logarithms were included in nineteenth and early twentieth century navigation and trigonometric texts. These days, the haversine form is also convenient in that it has no coefficient in front of the sin2 function.
- "Haversine Formula" | 2019-04-12 | 73 Upvotes 31 Comments
The Island of California refers to a long-held European misconception, dating from the 16th century, that the Baja California Peninsula was not part of mainland North America but rather a large island (spelled on early maps as Cali Fornia) separated from the continent by a strait now known as the Gulf of California.
One of the most famous cartographic errors in history, it was propagated on many maps during the 17th and 18th centuries, despite contradictory evidence from various explorers. The legend was initially infused with the idea that California was a terrestrial paradise, like the Garden of Eden or Atlantis.
- "Island of California" | 2014-06-11 | 99 Upvotes 40 Comments
Muḥammad ibn Mūsā al-Khwārizmī (Persian: Muḥammad Khwārizmī محمد بن موسی خوارزمی; c. 780 – c. 850), Arabized as al-Khwarizmi with al- and formerly Latinized as Algorithmi, was a Persian polymath who produced works in mathematics, astronomy, and geography. Around 820 CE he was appointed as the astronomer and head of the library of the House of Wisdom in Baghdad.
Al-Khwarizmi's popularizing treatise on algebra (The Compendious Book on Calculation by Completion and Balancing, c. 813–833 CE) presented the first systematic solution of linear and quadratic equations. One of his principal achievements in algebra was his demonstration of how to solve quadratic equations by completing the square, for which he provided geometric justifications. Because he was the first to treat algebra as an independent discipline and introduced the methods of "reduction" and "balancing" (the transposition of subtracted terms to the other side of an equation, that is, the cancellation of like terms on opposite sides of the equation), he has been described as the father or founder of algebra. The term algebra itself comes from the title of his book (specifically the word al-jabr meaning "completion" or "rejoining"). His name gave rise to the terms algorism and algorithm. His name is also the origin of (Spanish) guarismo and of (Portuguese) algarismo, both meaning digit.
In the 12th century, Latin translations of his textbook on arithmetic (Algorithmo de Numero Indorum) which codified the various Indian numerals, introduced the decimal positional number system to the Western world. The Compendious Book on Calculation by Completion and Balancing, translated into Latin by Robert of Chester in 1145, was used until the sixteenth century as the principal mathematical text-book of European universities.
In addition to his best-known works, he revised Ptolemy's Geography, listing the longitudes and latitudes of various cities and localities. He further produced a set of astronomical tables and wrote about calendaric works, as well as the astrolabe and the sundial. He also made important contributions to trigonometry, producing accurate sine and cosine tables, and the first table of tangents.
- "Muhammad ibn Musa al-Khwarizmi" | 2016-04-06 | 14 Upvotes 1 Comments
Null Island is a name for the area around the point where the prime meridian and the equator cross, located in international waters in the Gulf of Guinea (Atlantic Ocean) off the west African coast. In the WGS84 datum, this is at zero degrees latitude and longitude (0°N 0°E), and is the location of a buoy. The name 'Null Island' serves as both a joke based around the suppositional existence of an island there, and also as a name to which coordinates erroneously set to 0,0 are assigned in placenames databases in order to more easily find and fix them. The nearest land is a small islet offshore of Ghana, between Akwidaa and Dixcove at 4°45′30″N 1°58′33″W, 307.8 nmi (354.2 mi; 570.0 km) to the north.
- "Null Island" | 2019-12-22 | 46 Upvotes 56 Comments
Sailing stones (also known as sliding rocks, walking rocks, rolling stones, and moving rocks), are a geological phenomenon where rocks move and inscribe long tracks along a smooth valley floor without human or animal intervention. The movement of the rocks occurs when large ice sheets a few millimeters thick and floating in an ephemeral winter pond start to break up during sunny days. Frozen during cold winter nights, these thin floating ice panels are driven by wind and shove rocks at speeds up to 5 meters per minute.
Trails of sliding rocks have been observed and studied in various locations, including Little Bonnie Claire Playa in Nevada, and most famously at Racetrack Playa, Death Valley National Park, California, where the number and length of tracks are notable.
- "Sailing Stones" | 2010-03-12 | 24 Upvotes 5 Comments
The Waldseemüller map or Universalis Cosmographia ("Universal Cosmography") is a printed wall map of the world by German cartographer Martin Waldseemüller, originally published in April 1507. It is known as the first map to use the name "America". The name America is placed on what is now called South America on the main map. As explained in Cosmographiae Introductio, the name was bestowed in honor of the Italian Amerigo Vespucci.
The map is drafted on a modification of Ptolemy's second projection, expanded to accommodate the Americas and the high latitudes. A single copy of the map survives, presently housed at the Library of Congress in Washington, D.C.
Waldseemüller also created globe gores, printed maps designed to be cut out and pasted onto spheres to form globes of the Earth. The wall map, and his globe gores of the same date, depict the American continents in two pieces. These depictions differ from the small inset map in the top border of the wall map, which shows the two American continents joined by an isthmus.
- "Waldseemüller map" | 2014-05-16 | 39 Upvotes 24 Comments
Euro English or European English, less commonly known as EU English and EU Speak, is a pidgin dialect of English based on the technical jargon of the European Union and the native languages of its non-native English speaking population. It is mostly used among EU staff, expatriates from EU countries, young international travellers (such as exchange students in the EU’s Erasmus programme), European diplomats, and sometimes by other Europeans that use English as a second or foreign language (especially Continental Europeans).
- "Euro English" | 2020-10-04 | 39 Upvotes 27 Comments
The First Law of Geography, according to Waldo Tobler, is "everything is related to everything else, but near things are more related than distant things." This first law is the foundation of the fundamental concepts of spatial dependence and spatial autocorrelation and is utilized specifically for the inverse distance weighting method for spatial interpolation and to support the regionalized variable theory for kriging. It is a modern formulation of David Hume's principle of contiguity.
Tobler first presented his seminal idea during a meeting of the International Geographical Union's Commission on Qualitative Methods held in 1969 and later published by him in 1970. Though simple in its presentation, this idea is profound. Without it, "the full range of conditions anywhere on the Earth's surface could in principle be found packed within any small area. There would be no regions of approximately homogeneous conditions to be described by giving attributes to area objects. Topographic surfaces would vary chaotically, with slopes that were everywhere infinite, and the contours of such surfaces would be infinitely dense and contorted. Spatial analysis, and indeed life itself, would be impossible."
Less well known is his second law, which complements the first: "The phenomenon external to an area of interest affects what goes on inside".
- "Tobler's First Law of Geography" | 2020-10-30 | 63 Upvotes 17 Comments
The Zone of Death is the name given to the 50 sq mi (129.50 km2) Idaho section of Yellowstone National Park in which, as a result of a purported loophole in the Constitution of the United States, a criminal could theoretically get away with any crime, up to and including murder.
- "Zone of Death (Yellowstone)" | 2021-02-01 | 96 Upvotes 62 Comments