A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. As of February 2019, there are 352 minor planets suspected to have moons. Discoveries of minor-planet moons are important because the determination of their orbits provides estimates on the mass and density of the primary, allowing insights of their physical properties, not otherwise possible; the first modern era mention of the possibility of an asteroid satellite was in connection with an occultation of the bright star Gamma Ceti by the asteroid 6 Hebe in 1977. The observer, amateur astronomer Paul D. Maley, detected an unmistakable 0.5 second disappearance of this naked eye star from a site near Victoria, Texas. Many hours several observations were reported in Mexico attributed to the occultation by 6 Hebe itself. Although not confirmed, this documents the first formally documented case of a suspected companion of an asteroid. In addition to the terms satellite and moon, the term "binary" is sometimes used for minor planets with moons, "triple" for minor planets with two moons.
If one object is much bigger it can be referred to as the primary and its companion as secondary. The term double asteroid is sometimes used for systems in which the asteroid and its moon are the same size, while binary tends to be used independently from the relative sizes of the components; when binary minor planets are similar in size, the Minor Planet Center refers to them as "binary companions" instead of referring to the smaller body as a satellite. A good example of a true binary is the 90 Antiope system, identified in August 2000. Small satellites are referred to as moonlets. Prior to the era of the Hubble Space Telescope and space probes reaching the outer Solar System, attempts to detect satellites around asteroids were limited to optical observations from Earth. For example, in 1978, stellar occultation observations were claimed as evidence of a satellite for the asteroid 532 Herculina; however more-detailed imaging by the Hubble Telescope did not reveal a satellite, the current consensus is that Herculina does not have a significant satellite.
There were other similar reports of asteroids having companions in the following years. A letter in Sky & Telescope magazine at this time pointed to simultaneous impact craters on Earth, suggesting that these craters were caused by pairs of gravitationally bound objects. In 1993, the first asteroid moon was confirmed when the Galileo probe discovered the small Dactyl orbiting 243 Ida in the asteroid belt; the second was discovered around 45 Eugenia in 1998. In 2001, 617 Patroclus and its same-sized companion Menoetius became the first known binary asteroids in the Jupiter trojans; the first trans-Neptunian binary after Pluto–Charon, 1998 WW31, was optically resolved in 2002. Triple or trinary minor planets, are known since 2005, when the asteroid 87 Sylvia was discovered to have two satellites, making it the first known triple system; this was followed by the discovery of a second moon orbiting 45 Eugenia. In 2005, the dwarf planet Haumea was discovered to have two moons, making it the second trans-Neptunian object after Pluto known to have more than one moon.
Additionally, 216 Kleopatra and 93 Minerva were discovered to be trinary asteroids in 2008 and 2009 respectively. Since the first few triple minor planets were discovered, more continue to be discovered at a rate of about one a year. Most discovered were two moons orbiting large near-earth asteroid 3122 Florence, bringing the number of known trinary systems in the Solar System up to 14; the following table lists all satellites of triple systems chronologically by their discovery date, starting with Charon, discovered in 1978. The data about the populations of binary objects are still patchy. In addition to the inevitable observational bias the frequency appears to be different among different categories of objects. Among asteroids, an estimated 2% would have satellites. Among trans-Neptunian objects, an estimated 11% are thought to be binary or multiple objects, the majority of the large TNOs have at least one satellite, including all four IAU-listed dwarf planets. More than 50 binaries are known in each of the main groupings: near-Earth asteroids, belt asteroids, trans-Neptunian objects, not including numerous claims based on light-curve variation.
Two binaries have been found so far among centaurs with semi-major axes smaller than Neptune. Both are double ring systems around 2060 Chiron and 10199 Chariklo, discovered in 1994–2011 and 2013 respectively; the origin of minor-planet moons is not known with certainty, a variety of theories exist. A accepted theory is that minor-planet moons are formed from debris knocked off of the primary by an impact. Other pairings may be formed. Formation by collision is constrained by the angular momentum of the components, i.e. by the masses and their separation. Close binaries fit this model. Distant binaries however, with components of comparable size, are unlikely to have followed this scenario, unless considerable mass has been lost in the event; the distances of the components for the known binaries vary from a few hundreds of kilometres to more than 3000 km for the asteroids. Among TNOs, the known separations vary from 3,000 to 50,000 km. What is "typical" for a binary system tends to depend on its location in the Solar System (presumably because of different modes
The term apsis refers to an extreme point in the orbit of an object. It denotes either the respective distance of the bodies; the word comes via Latin from Greek, there denoting a whole orbit, is cognate with apse. Except for the theoretical possibility of one common circular orbit for two bodies of equal mass at diametral positions, there are two apsides for any elliptic orbit, named with the prefixes peri- and ap-/apo-, added in reference to the body being orbited. All periodic orbits are, according to Newton's Laws of motion, ellipses: either the two individual ellipses of both bodies, with the center of mass of this two-body system at the one common focus of the ellipses, or the orbital ellipses, with one body taken as fixed at one focus, the other body orbiting this focus. All these ellipses share a straight line, the line of apsides, that contains their major axes, the foci, the vertices, thus the periapsis and the apoapsis; the major axis of the orbital ellipse is the distance of the apsides, when taken as points on the orbit, or their sum, when taken as distances.
The major axes of the individual ellipses around the barycenter the contributions to the major axis of the orbital ellipses are inverse proportional to the masses of the bodies, i.e. a bigger mass implies a smaller axis/contribution. Only when one mass is sufficiently larger than the other, the individual ellipse of the smaller body around the barycenter comprises the individual ellipse of the larger body as shown in the second figure. For remarkable asymmetry, the barycenter of the two bodies may lie well within the bigger body, e.g. the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If the smaller mass is negligible compared to the larger the orbital parameters are independent of the smaller mass. For general orbits, the terms periapsis and apoapsis are used. Pericenter and apocenter are equivalent alternatives, referring explicitly to the respective points on the orbits, whereas periapsis and apoapsis may refer to the smallest and largest distances of the orbiter and its host.
For a body orbiting the Sun, the point of least distance is the perihelion, the point of greatest distance is the aphelion. The terms become apastron when discussing orbits around other stars. For any satellite of Earth, including the Moon, the point of least distance is the perigee and greatest distance the apogee, from Ancient Greek Γῆ, "land" or "earth". For objects in lunar orbit, the point of least distance is sometimes called the pericynthion and the greatest distance the apocynthion. Perilune and apolune are used. In orbital mechanics, the apsides technically refer to the distance measured between the barycenters of the central body and orbiting body. However, in the case of a spacecraft, the terms are used to refer to the orbital altitude of the spacecraft above the surface of the central body; these formulae characterize the pericenter and apocenter of an orbit: Pericenter Maximum speed, v per = μ a, at minimum distance, r per = a. Apocenter Minimum speed, v ap = μ a, at maximum distance, r ap = a.
While, in accordance with Kepler's laws of planetary motion and the conservation of energy, these two quantities are constant for a given orbit: Specific relative angular momentum h = μ a Specific orbital energy ε = − μ 2 a where: a is the semi-major axis: a = r per + r ap 2 μ is the standard gravitational parameter e is the eccentricity, defined as e = r ap − r per r ap + r per = 1 − 2 r ap r per + 1 Note t
Jet Propulsion Laboratory
The Jet Propulsion Laboratory is a federally funded research and development center and NASA field center in La Cañada Flintridge, United States, though it is referred to as residing in Pasadena, because it has a Pasadena ZIP Code. Founded in the 1930s, the JPL is owned by NASA and managed by the nearby California Institute of Technology for NASA; the laboratory's primary function is the construction and operation of planetary robotic spacecraft, though it conducts Earth-orbit and astronomy missions. It is responsible for operating NASA's Deep Space Network. Among the laboratory's major active projects are the Mars Science Laboratory mission, the Mars Reconnaissance Orbiter, the Juno spacecraft orbiting Jupiter, the NuSTAR X-ray telescope, the SMAP satellite for earth surface soil moisture monitoring, the Spitzer Space Telescope, it is responsible for managing the JPL Small-Body Database, provides physical data and lists of publications for all known small Solar System bodies. The JPL's Space Flight Operations Facility and Twenty-Five-Foot Space Simulator are designated National Historic Landmarks.
JPL traces its beginnings to 1936 in the Guggenheim Aeronautical Laboratory at the California Institute of Technology when the first set of rocket experiments were carried out in the Arroyo Seco. Caltech graduate students Frank Malina, Qian Xuesen, Weld Arnold, Apollo M. O. Smith, along with Jack Parsons and Edward S. Forman, tested a small, alcohol-fueled motor to gather data for Malina's graduate thesis. Malina's thesis advisor was engineer/aerodynamicist Theodore von Kármán, who arranged for U. S. Army financial support for this "GALCIT Rocket Project" in 1939. In 1941, Parsons, Martin Summerfield, pilot Homer Bushey demonstrated the first jet-assisted takeoff rockets to the Army. In 1943, von Kármán, Malina and Forman established the Aerojet Corporation to manufacture JATO rockets; the project took on the name Jet Propulsion Laboratory in November 1943, formally becoming an Army facility operated under contract by the university. During JPL's Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate-range ballistic missiles.
These missiles were the first US ballistic missiles developed at JPL. It developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, the forerunner of the Aerobee sounding rocket. At various times, it carried out rocket testing at the White Sands Proving Ground, Edwards Air Force Base, Goldstone, California. In 1954, JPL teamed up with Wernher von Braun's engineers at the Army Ballistic Missile Agency's Redstone Arsenal in Huntsville, Alabama, to propose orbiting a satellite during the International Geophysical Year; the team lost that proposal to Project Vanguard, instead embarked on a classified project to demonstrate ablative re-entry technology using a Jupiter-C rocket. They carried out three successful sub-orbital flights in 1956 and 1957. Using a spare Juno I, the two organizations launched the United States' first satellite, Explorer 1, on January 31, 1958. JPL was transferred to NASA in December 1958, becoming the agency's primary planetary spacecraft center.
JPL engineers designed and operated Ranger and Surveyor missions to the Moon that prepared the way for Apollo. JPL led the way in interplanetary exploration with the Mariner missions to Venus and Mercury. In 1998, JPL opened the Near-Earth Object Program Office for NASA; as of 2013, it has found 95% of asteroids that are a kilometer or more in diameter that cross Earth's orbit. JPL was early to employ female mathematicians. In the 1940s and 1950s, using mechanical calculators, women in an all-female computations group performed trajectory calculations. In 1961, JPL hired Dana Ulery as the first female engineer to work alongside male engineers as part of the Ranger and Mariner mission tracking teams. JPL has been recognized four times by the Space Foundation: with the Douglas S. Morrow Public Outreach Award, given annually to an individual or organization that has made significant contributions to public awareness of space programs, in 1998; when it was founded, JPL's site was west of a rocky flood-plain – the Arroyo Seco riverbed – above the Devil's Gate dam in the northwestern panhandle of the city of Pasadena.
While the first few buildings were constructed in land bought from the city of Pasadena, subsequent buildings were constructed in neighboring unincorporated land that became part of La Cañada Flintridge. Nowadays, most of the 177 acres of the U. S. federal government-owned NASA property that makes up the JPL campus is located in La Cañada Flintridge. Despite this, JPL still uses a Pasadena address as its official mailing address; the city of La Cañada Flintridge was incorporated in 1976, well after JPL attained international recognition as a Pasadena institution. There has been occasional rivalry between the two cities over the issue of which one should be mentioned in the media as the home of the laboratory. There are 6,000 full-time Caltech employees, a few thousand additional contractors working on any given day. NASA has a resident office at the facility staffed by federal managers who oversee JPL's activities and work for NASA. There are some Caltech graduate students, college student interns and co-op students.
The JPL Education Office serves educators and students by providi
A near-Earth object is any small Solar System body whose orbit brings it to proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun is less than 1.3 astronomical units. If a NEO's orbit crosses the Earth's and the object is larger than 140 meters across, it is considered a hazardous object. Most known PHOs and NEOs are asteroids. There are over 19,000 known near-Earth asteroids, over a hundred short-period near-Earth comets, a number of solar-orbiting spacecraft and meteoroids large enough to be tracked in space before striking the Earth, it is now accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of greater awareness of the potential danger some of the asteroids or comets pose; when impacting the Earth, asteroids as small as 20 m cause sufficiently strong shock waves and heat to damage the local environment and populations.
Larger asteroids penetrate the atmosphere to the surface of the Earth, producing craters if they hit ground and tsunamis if water bodies are hit. It is in principle possible to deflect asteroids, methods of mitigation are being researched. Based on the orbit calculations of identified NEOs, their risk of future impact is assessed on two scales, the Torino scale and the more complex Palermo scale, both of which rate a risk of any significance with values above 0; some NEOs have had temporarily positive Torino or Palermo scale ratings after their discovery, but as of March 2018, more precise calculations based on subsequent observations led to a reduction of the rating to or below 0 in all cases. Since 1998, the United States, the European Union, other nations are scanning for NEOs in an effort called Spaceguard; the initial US Congress mandate to NASA of cataloging at least 90% of NEOs that are at least 1 kilometre in diameter, which would cause a global catastrophe in case of an impact with Earth, had been met by 2011.
In years, the survey effort has been expanded to objects as small as about 140 m across, which still have the potential for large-scale, though not global, damage. NEOs have low surface gravity, many have Earth-like orbits making them easy targets for spacecraft; as of January 2019, five near-Earth comets and five near-Earth asteroids have been visited by spacecraft. Two near-Earth asteroids are being orbited by spacecraft that will return asteroid samples back to Earth. Plans for commercial asteroid mining have been drafted by private companies; the major technical astronomical definition for Near-Earth objects are small Solar System bodies with orbits around the Sun that by definition lie between 0.983 and 1.3 astronomical units away from the Sun. Thus, NEOs are not currently near the Earth, but they can approach the Earth closely. However, the term is used more flexibly sometimes, for example for objects in orbit around the Earth or for quasi-satellites, which have a more complex orbital relationship with the Earth.
When a NEO is detected, like all other small Solar System bodies, it is submitted to the International Astronomical Union's Minor Planet Center for cataloging. MPC maintains separate lists of potential NEOs; the orbits of some NEOs intersect that of the Earth, so they pose a collision danger. These are considered hazardous objects. For the asteroids among PHOs, the hazardous asteroids, MPC maintains a separate list. NEOs are catalogued by two separate units of the Jet Propulsion Laboratory of the National Aeronautics and Space Administration: the Center for Near Earth Object Studies and the Solar System Dynamics Group. PHAs are defined based on parameters relating to their potential to approach the Earth dangerously closely. Objects with an Earth minimum orbit intersection distance of 0.05 AU or less and an absolute magnitude of 22.0 or brighter are considered PHAs. Objects that cannot approach closer to the Earth than 0.05 AU, or are smaller than about 140 m in diameter, are not considered PHAs.
NASA's catalog of near-Earth objects includes the approach distances of asteroids and comets. The first near-Earth objects to be observed by humans were comets, their extraterrestrial nature was recognised and confirmed only after Tycho Brahe tried to measure the distance of a comet through its parallax in 1577. The 1758–1759 return of Halley's Comet was the first comet appearance predicted in advance; the first near-Earth asteroid to be discovered was 433 Eros in 1898. The asteroid was subject to several observation campaigns, because measurements of its orbit enabled a precise determination of the distance of the Earth from the Sun. In has been said. In 1937, asteroid 69230 Hermes was discovered when it passed the Earth at twice the distance of the Moon. Hermes was considered a threat. Hermes was re-discovered in 2003, is now known to be no threat for at least the next century. On June 14, 1968, the 1.4 km diameter asteroid 1566 Icarus passed Earth at a distance of 0.042482 AU (6,355,2
Taunton is a city in Bristol County, United States. It is the seat of Bristol County. Taunton is situated on the Taunton River which winds its way through the city on its way to Mount Hope Bay, 10 miles to the south. At the 2010 census, the city had a population of 55,874. Thomas Hoye Jr. is the current mayor of Taunton, has held the position since 2012. Founded in 1637 by members of the Plymouth Colony, Taunton is one of the oldest towns in the United States; the Native Americans called the region Cohannet and Titicut before the arrival of the Europeans. Taunton is known as the "Silver City", as it was a historic center of the silver industry beginning in the 19th century when companies such as Reed & Barton, F. B. Rogers, Poole Silver, others produced fine-quality silver goods in the city. Since December 1914, the city of Taunton has provided a large annual light display each December on Taunton Green, giving it the additional nickname of "Christmas City"; the original boundaries of Taunton included the land now occupied by many surrounding towns, including Norton, Mansfield, Raynham and Lakeville.
Possession of the latter is still noted by the naming of Taunton Hill in Assonet. Taunton was founded by settlers from England and incorporated as a town on September 3, 1639. Most of the town's settlers were from Taunton in Somerset, which led early settlers to name the settlement after that town. At the time of Taunton's incorporation, they explained their choice of name as being “in honor and love to our dear native country.” Prior to 1640, the Taunton area was called Tetiquet or Titiquet. The English founders of Taunton purchased the land from the Nemasket Indians in 1637 as part of the Tetiquet Purchase and the remaining native families were relocated to the praying town of Ponkapoag in current day Canton, MA. A central figure among the founders was Elizabeth Poole, believed to have been the first woman to found a settlement in the Americas and, contrary to local folklore, did not take part in the town purchase but was among its greatest beneficiaries and played a significant role in the founding of its church.
Described as "the foundress of Taunton" and its matriarch, Poole "was accorded equality of rights, whether in the purchase of lands, in the sharing of iron works holdings," having been a financier of the settlement's first dam and mill built for the manufacture of bar iron. Plymouth Colony was formally divided into counties on June 2, 1685, with Taunton becoming the shire town of Bristol County; the counties of Plymouth Colony were transferred to the Province of Massachusetts Bay on the arrival of its charter and governor on May 14, 1692. The Taunton area has been the site of skirmishes and battles during various conflicts, including King Philip's War and the American Revolution. Taunton was re-incorporated as a city on May 11, 1864. In 1656, the first successful iron works in Plymouth Colony was established on the Two Mile River, in what is now part of Raynham; the Taunton Iron Works operated for over 200 years until 1876. It was the first of many iron industries in Taunton. During the 19th century, Taunton became known as the "Silver City", as it was home to many silversmithing operations, including Reed & Barton, F.
B. Rogers, Poole Silver. In the 19th century, Taunton was the center of an important iron-making industry, utilizing much bog iron from the numerous swamps in the surrounding area; the iron industry in Taunton produced a variety of goods including stoves and machinery. One of the more successful companies during this period was the Mason Machine Works, founded by William Mason, which produced machinery for the textile industry, as well as steam locomotives; the Taunton Locomotive Works operated in the city during this time. Taunton was home to several textile mills and other industries, such as felt and brick making. During the 19th century, Taunton was a major shipping point for grain from the inland rural farm areas of Massachusetts to the rest of the nation via Weir Village and the Taunton River. With the advent of the railroad, Taunton would become an important transportation hub due to its central location; the city formed the Taunton Municipal Light Plant in 1897, when it decided to purchase the floundering Taunton Electric Lighting Company, making it a publicly owned electric utility.
Today, TMLP provides electric service to 34,000 customers in Taunton, Berkley and sections of Dighton and Bridgewater. TMLP is governed by a three-member Board of Commissioners, elected by the citizens of Taunton. Built in 1942, U. S. Army Camp Myles Standish was a departure point for over a million U. S. and allied military personnel bound for Europe during World War II. It functioned as a prisoner of war camp housing German and Italian soldiers. While Camp Myles Standish was closed in 1946, it was re-purposed as the Paul A Dever School, a facility that housed mentally disabled persons; the school was shut down in the 1980's. A portion of the former Camp Myles Standish was turned into the Myles Standish Industrial Park; the Myles Standish Industrial Park in Taunton's north end is one of the largest in New England. The National Weather Service operates a regional weather forecast office that serves much of Massachusetts, all of Rhode Island, most of northern Connecticut there; the National Weather Service operates the Northeast River Forecast Center on the site, serving New England and most of New York state.
Several major companies operate in other parts of the city. In October 2005, the Whittenton Pond Dam north
The National Aeronautics and Space Administration is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research. NASA was established in 1958; the new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles; the agency is responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA science is focused on better understanding Earth through the Earth Observing System. From 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1.
In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year. An effort for this was the American Project Vanguard. After the Soviet launch of the world's first artificial satellite on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts; the US Congress, alarmed by the perceived threat to national security and technological leadership, urged immediate and swift action. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever. On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating: It is of great urgency and importance to our country both from consideration of our prestige as a nation as well as military necessity that this challenge be met by an energetic program of research and development for the conquest of space... It is accordingly proposed that the scientific research be the responsibility of a national civilian agency...
NACA is capable, by rapid extension and expansion of its effort, of providing leadership in space technology. While this new federal agency would conduct all non-military space activity, the Advanced Research Projects Agency was created in February 1958 to develop space technology for military application. On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA; when it began operations on October 1, 1958, NASA absorbed the 43-year-old NACA intact. A NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program led by Wernher von Braun, now working for the Army Ballistic Missile Agency, which in turn incorporated the technology of American scientist Robert Goddard's earlier works. Earlier research efforts within the US Air Force and many of ARPA's early space programs were transferred to NASA.
In December 1958, NASA gained control of the Jet Propulsion Laboratory, a contractor facility operated by the California Institute of Technology. The agency's leader, NASA's administrator, is nominated by the President of the United States subject to approval of the US Senate, reports to him or her and serves as senior space science advisor. Though space exploration is ostensibly non-partisan, the appointee is associated with the President's political party, a new administrator is chosen when the Presidency changes parties; the only exceptions to this have been: Democrat Thomas O. Paine, acting administrator under Democrat Lyndon B. Johnson, stayed on while Republican Richard Nixon tried but failed to get one of his own choices to accept the job. Paine was confirmed by the Senate in March 1969 and served through September 1970. Republican James C. Fletcher, appointed by Nixon and confirmed in April 1971, stayed through May 1977 into the term of Democrat Jimmy Carter. Daniel Goldin was appointed by Republican George H. W. Bush and stayed through the entire administration of Democrat Bill Clinton.
Robert M. Lightfoot, Jr. associate administrator under Democrat Barack Obama, was kept on as acting administrator by Republican Donald Trump until Trump's own choice Jim Bridenstine, was confirmed in April 2018. Though the agency is independent, the survival or discontinuation of projects can depend directly on the will of the President; the first administrator was Dr. T. Keith Glennan appointed by Republican President Dwight D. Eisenhower. During his term he brought together the disparate projects in American space development research; the second administrator, James E. Webb, appointed by President John F. Kennedy, was a Democrat who first publicly served under President Harry S. Truman. In order to implement the Apollo program to achieve Kennedy's Moon la
The kilometre, or kilometer is a unit of length in the metric system, equal to one thousand metres. It is now the measurement unit used for expressing distances between geographical places on land in most of the world. K is used in some English-speaking countries as an alternative for the word kilometre in colloquial writing and speech. A slang term for the kilometre in the US and UK military is klick. There are two common pronunciations for the word; the former follows a pattern in English whereby metric units are pronounced with the stress on the first syllable and the pronunciation of the actual base unit does not change irrespective of the prefix. It is preferred by the British Broadcasting Corporation and the Australian Broadcasting Corporation. Many scientists and other users in countries where the metric system is not used, use the pronunciation with stress on the second syllable; the latter pronunciation follows the stress pattern used for the names of measuring instruments. The problem with this reasoning, however, is that the word meter in those usages refers to a measuring device, not a unit of length.
The contrast is more obvious in countries using the British rather than American spelling of the word metre. When Australia introduced the metric system in 1975, the first pronunciation was declared official by the government's Metric Conversion Board. However, the Australian prime minister at the time, Gough Whitlam, insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word. By the 8 May 1790 decree, the Constituent assembly ordered the French Academy of Sciences to develop a new measurement system. In August 1793, the French National Convention decreed the metre as the sole length measurement system in the French Republic; the first name of the kilometre was "Millaire". Although the metre was formally defined in 1799, the myriametre was preferred to the "kilometre" for everyday use; the term "myriamètre" appeared a number of times in the text of Develey's book Physique d'Emile: ou, Principes de la science de la nature, while the term kilometre only appeared in an appendix.
French maps published in 1835 had scales showing myriametres and "lieues de Poste". The Dutch gave it the local name of the mijl, it was only in 1867 that the term "kilometer" became the only official unit of measure in the Netherlands to represent 1000 metres. Two German textbooks dated 1842 and 1848 give a snapshot of the use of the kilometre across Europe - the kilometre was in use in the Netherlands and in Italy and the myriametre was in use in France. In 1935, the International Committee for Weights and Measures abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude. In the United Kingdom, road signs show distances in miles and location marker posts that are used for reference purposes by road engineers and emergency services show distance references in unspecified units which are kilometre-based; the advent of the mobile phone has been instrumental in the British Department for Transport authorising the use of driver location signs to convey the distance reference information of location marker posts to road users should they need to contact the emergency services.
In the US, the National Highway System Designation Act of 1995 prohibits the use of federal-aid highway funds to convert existing signs or purchase new signs with metric units. The Executive Director of the US Federal Highway Administration, Jeffrey Paniati, wrote in a 2008 memo: "Section 205 of the National Highway System Designation Act of 1995 prohibited us from requiring any State DOT to use the metric system during project development activities. Although the State DOT's had the option of using metric measurements or dual units, all of them abandoned metric measurements and reverted to sole use of inch-pound values." The Manual on Uniform Traffic Control Devices since 2000 is published in both metric and American Customary Units. Some sporting disciplines feature 1000 m races in major events, but in other disciplines though world records are catalogued, the one kilometre event remains a minority event; the world records for various sporting disciplines are: Conversion of units, for comparison with other units of length Cubic metre Metric prefix Mileage Odometer Orders of magnitude Square kilometre Media related to Distance indicators at Wikimedia Commons