20000 Varuna ("VAR oo na") is a Kuiper Belt object about 1060 km in diameter, estimated from a combination of thermal and optical measurements.
Little is known about it. It has a rotational period of approximately 3.17 hours (or 6.34 hours, depending on whether the light curve is single or double-peaked). It has a density of approximately 1 g/cm⁹ (as dense as water), which implies that it may not be a fully solid body (Jewitt & Sheppard, 2002). The surface is darker than the surface of Pluto indicating it is largely devoid of ice. (Jewitt, et al., 2001)
It is named after the Hindu god Varuna. It previously had the provisional designation and has been precovered in plates dating back to 1953.
The Kuiper belt ("KIE per") is an area of the solar system extending from within the orbit of Neptune (at 30 AU) to 50 AU from the Sun, at inclinations consistent with the ecliptic.
Objects within the Kuiper Belt are referred to by the IAU as trans-Neptunian objects (a type of minor planet). They are sometimes also called asteroids.
The outer boundary of the Kuiper belt is not defined arbitrarily; rather, there appears to be a real and fairly sharp dropoff in objects beyond a certain distance. This is sometimes called the "Kuiper gap" or "Kuiper cliff". The cause for this remains a mystery; one possible explanation would be a hypothetical Earth-sized or Mars-sized object sweeping away debris.
Origins
Modern computersimulations show the Kuiper belt to have been formed by the work of Jupiter, the young Jupiter having used its considerable gravity to eject smaller bodies which didn't all escape completely, and also having been formed in-situ. The same simulations and other theories predict there should be bodies of significant mass in the belt, Mars-sized or Earth-sized.
The first astronomers to suggest the existence of this belt were Frederick C. Leonard in 1930 and Kenneth E. Edgeworth in 1943. In 1951Gerard Kuiper suggested that the belt was the source of short period comets (those having an orbital period of less than 200 years). More detailed conjectures about objects in the belt were done by Al G. W. Cameron in 1962, Fred L. Whipple in 1964, and Julio Fernandez in 1980. The belt and the objects in it were named after Kuiper after the discovery of .
Name
An alternative name, Edgeworth-Kuiper belt is used to credit Edgeworth. The term trans-Neptunian object is recommended for objects in the belt by several scientific groups because the term is less controversial than all others — it is not a synonym though, as TNOs include all objects orbiting the Sun at the outer edge of the solar system, not just those in the Kuiper belt.
Kuiper belt objects
Discoveries thus far
Over 800 Kuiper belt objects (KBOs) (a subset of trans-Neptunian objects (TNOs)) have been discovered in the belt, almost all of them since 1992. Among the largest are Pluto and Charon, but since the year 2000 other large objects that approached their size were identified. 50000 Quaoar, discovered in 2002, which is a KBO, is half the size of Pluto and is larger than the largest asteroid1 Ceres. and , both announced on 29 July2005, are larger still. Other objects, such as 28978 Ixion (discovered in 2001) and 20000 Varuna (discovered in 2000) while smaller than Quaoar, are nonetheless quite sizable. The object , estimated to be one fifth to half the size of Pluto, is conspicuous in that its orbit is tilted 47 degrees from the plane of the solar system [http://www.cfeps.astrosci.ca/4b7/]. The exact classification of these objects is unclear, since they are probably fairly different from the asteroids of the asteroid belt.
Neptune's moon Triton is commonly thought to be a captured KBO.
Orbital trajectories
KBOs are by (current) definition limited to 30-44 AU from the Sun. This is not merely an arbitrary definition but reflects a real lack of objects beyond a certain distance. However, most of the known KBOs are detected near their closest approaches to the Sun since they appear dimmer at greater distances.
Some KBOs that also periodically travel inside Neptune's orbit are in 1:2, 2:3 (plutinos), 2:5, 3:4, 3:5, 4:5, or 4:7 orbital resonance with Neptune. Cubewanos, or "classical KBOs" are in more circular nonresonant orbits, which form the core of the belt.
The belt should not be confused with the Oort cloud, which is not limited to the plane of the solar system and is more distant.
Term "kuiper belt object"
Most models of solar system formation show icy planetoids first forming in the Kuiper belt, and then subsequent gravitational interactions displaced some of them outwards into the so-named scattered disc. While, strictly speaking, a KBO is any object that orbits exclusively within the defined Kuiper belt region regardless of origin or composition, in some scientific circles the term has become synonymous with any icy planetoid native to the outer solar sytem believed to have been part of that initial class, even if it has orbited beyond the belt for billions of years. Discoverer Michael E. Brown, for instance, has referred to as a KBO, despite it having an orbital radius of 67 AU, well clear of the Kuiper cliff. Other leading trans-Neptunian researchers have been more cautious in applying the KBO label to objects clearly outside the belt in the current epoch.
Largest KBOs
The brightest known KBOs (with absolute magnitudes < 4.0), are:
The list has been sorted by increasing absolute magnitude. Estimated diameter is greatly affected by surface albedo which is often assumed, rather than measured. Some potentially large Kuiper belt objects have not been included.
Sources: [http://arxiv.org/ftp/astro-ph/papers/0502/0502229.pdf], [http://www.ifa.hawaii.edu/faculty/jewitt/kb/big_kbo.html], [http://www.aas.org/publications/baas/v37n3/dps2005/446.htm]
External links and data sources
- [http://www.ifa.hawaii.edu/faculty/jewitt/kb.html Dave Jewitt's page @ University of Hawaii]
- [http://www.ifa.hawaii.edu/faculty/jewitt/kb/gerard.html The belt's name]
- [http://www.boulder.swri.edu/ekonews/ The Kuiper Belt Electronic Newsletter]
- [http://www.johnstonsarchive.net/astro/tnos.html Wm. Robert Johnston's TNO page]
- [http://cfa-www.harvard.edu/iau/lists/OuterPlot.html Minor Planet Center: Plot of the Outer Solar System], illustrating Kuiper gap
Category:Trans-Neptunian objectsko:카이퍼 대ms:Lingkaran Kuiperja:エッジワース＝カイパー・ベルトth:แถบไคเปอร์
Water
:This article focuses on water as it is experienced in everyday life. See water (molecule) for information on the chemical and physical properties of pure water (H2O, hydrogen oxide).
Water (from the Old English word wæter; c.f German "Wasser", from PIE - wod-or, "water") is a tasteless, odorless, and nearly colorless (it has a slight hint of blue) substance in its pure form that is essential to all known forms of life and is known also as the most universal solvent. Water is an abundant substance on Earth. It exists in many places and forms. It appears mostly in the oceans and polar ice caps, but also as clouds, rain water, rivers, freshwater aquifers, and sea ice. On the planet, water is continuously moving through the cycle involving evaporation, precipitation, and runoff to the sea.
Water fit for human consumption is called potable water. This natural resource is becoming more scarce in certain places as human population in those places increases, and its availability is a major social and economic concern.
Molecular properties
Forms of water
potable water]
Water takes many different shapes on earth: water vapor and clouds in the sky, waves and icebergs in the sea, glaciers in the mountain, aquifers in the ground, to name but a few. Through evaporation, precipitation, and runoff, water is continuously flowing from one form to another, in what is called the water cycle.
Because of the importance of precipitation to agriculture, and to mankind in general, different names are given to its various forms: while rain is common in most countries, other phenomena are quite surprising when seen for the first time. Hail, snow, fog or dew are examples. When appropriately lit, water drops in the air can refractsunlight to produce rainbows.
Similarly, water runoffs have played major roles in human history as rivers and irrigation brought the water needed for agriculture. Rivers and seas offered opportunity for travel and commerce. Through erosion, runoffs played a major part in shaping the environment providing river valleys and deltas which provide rich soil and level ground for the establishment of population centers.
Water also infiltrates the ground and goes into aquifers. This groundwater later flows back to the surface in springs, or more spectacularly in hot springs and geysers. Groundwater is also extracted artificially in wells.
Because water can contain many different substances, it can taste or smell very differently. In fact, humans and other animals have developed their senses to be able to evaluate the drinkability of water: animals generally dislike the taste of salty sea water and the putrid swamps and favor the purer water of a mountain spring or aquifer.
Water in biology
From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. Water carries out this role by allowing organic compounds to react in ways that ultimately allows replication. It is a good solvent and has a high surface tension, and thus allows organic compounds and living things to be transported in it. Fresh water has its greatest density at 4°C, then becoming less dense as it freezes or heats up from this point. As a stable, polar molecule prevalent in the atmosphere, it plays an important atmospheric role as an absorber of infrared radiation, crucial in the atmospheric greenhouse effect without of which, the average surface temperature would be −18° Celsius. Water also has an unusually high specific heat, which plays many roles in regulating global and regional climate, such as the Gulf Stream climate, allowing life to survive.
Water is a very good solvent, chemically not unlike ammonia, and dissolves many types of substances, such as various salts and sugar, and facilitates their chemical interaction, which aids complex metabolisms.
Some substances, however, do not mix well with water, including oils and other hydrophobic substances. Cell membranes, composed of lipids and proteins, take advantage of this property to carefully control interactions between their contents and external chemicals. This is facilitated somewhat by the surface tension of water.
Water drops are stable due to the high surface tension of water caused by the strong intermolecular forces called cohesive forces. This can be seen when small quantities of water are put onto a nonsoluble surface such as polythene: the water stays together as drops. On extremely clean glass the water may form a thin film because the molecular forces between glass and water molecules (adhesive forces) are stronger than the cohesive forces. This property plays a key role in planttranspiration.
A simple but environmentally important and unique property of water is that its common solid form, ice, floats on the liquid. This solid phase is less dense than liquid water, due to the geometry of the strong hydrogen bonds which are formed only at lower temperatures. For almost all other substances and for all other 11 uncommon phases of water ice except ice-XI, the solid form is more dense than the liquid form. Fresh water is most dense at 4°C, and will sink by convection as it cools to that temperature, and if it becomes colder it will rise instead. This reversal will cause deep water to remain warmer than shallower freezing water, so that ice in a body of water will form first at the surface and progress downward, while the majority of the water underneath will hold a constant 4°C. This effectively insulates a lake floor from the cold.
While this behavior may seem obvious, even intuitive, it should be noted that almost all other chemicals are denser as solids than they are as liquids, and freeze from the bottom up.
Life on earth has evolved with and adapted itself to the important features of water. The existence of abundant liquid, vapor and solid forms of water on Earth has been an important factor in the abundant colonization of Earth's various environments by life-forms adapted to those varying and often extreme conditions.
Civilizations have historically flourished around rivers and major waterways; Mesopotamia, the so-called cradle of civilization, is situated between two major rivers. Large metropolises like London, Paris, New York, and Tokyo owe their success in part to their easy accessibility via water and the resultant expansion of trade. Islands with safe water ports, like Singapore and Hong Kong, have flourished for precisely this reason. In places such as North Africa and the Middle East, where water is scarcer, access to clean drinking water was and is a major factor in human development.
Astronomical position of Earth and impact on its water
Mesopotamia
The coexistence of the solid, liquid, and gaseous phases of water on Earth is vital to the origin, evolution, and continued existence of life on Earth. However, if the Earth's location in the solar system were even marginally closer or further from the Sun (ie, a million miles or so), the conditions which allow the three forms to be present simultaneously would be far less likely to exist.
Earth's mass allows gravity to hold an atmosphere. Water vapor and carbon dioxide in the atmosphere provides a greenhouse effect which helps maintain a relatively steady surface temperature. If Earth were less massive, a thinner atmosphere would cause temperature extremes preventing the accumulation of water except in polar ice caps (as on Mars). According to the solar nebula model of the solar system's formation, Earth's mass may be largely due to its distance from the Sun.
The distance between Earth and the Sun and the combination of solar radiation received and the greenhouse effect of the atmosphere ensures that its surface is neither too cold nor too hot for liquid water. If Earth were more distant, most water would be frozen. If Earth were nearer to the Sun, its higher surface temperature would limit the formation of ice caps, or cause water to exist only as vapor. In the former case, the low albedo of oceans would cause Earth to absorb more solar energy. In the second case, a runaway greenhouse effect and inhospitable conditions similar to Venus would result.
It has been proposed that life itself may maintain the conditions that have allowed its continued existence. The surface temperature of Earth has been relatively constant through geologic time despite varying solar flux, indicating that a dynamic process governs Earth's temperature via a combination of greenhouse gases and surface or atmospheric albedo. This proposal is known as the Gaia hypothesis.
Human uses of water
Gaia hypothesis
All known forms of life depend on water. Water is a vital part of many metabolic processes within the body. Significant quantities of water are used during the digestion of food. (Note however that some bacteria and plantseeds can enter a cryptobiotic state for an indefinite period when dehydrated, and come back to life when returned to a wet environment)
About 72% of the fat free mass of the human body is made of water. To function properly the body requires between one and seven litres of water per day to avoid dehydration, the precise amount depending on the level of activity, temperature, humidity, and other factors. It is not clear how much water intake is needed by healthy people. However, for those who do not have kidney problems, it is rather difficult to drink too much water, but (especially in warm humid weather and while exercising) dangerous to drink too little. People do often drink far more water than necessary while exercising, however, putting them at risk of water intoxication, which is frequently fatal. The "fact" that a person should consume eight glasses of water per day cannot be traced back to a scientific source. However, leading dieticians and nutritionists will tell you that this is the RDI (Recommended Daily Intake) of water. [http://ajpregu.physiology.org/cgi/content/full/283/5/R993]. The latest dietary reference intake report by the National Research Council recommended 2.7 liters of water total (including food sources) for women and 3.7 liters for men[http://www.iom.edu/report.asp?id=18495]. Water is lost from the body in urine and feces, through sweating, and by exhalation of water vapor in the breath.
Humans require water that does not contain too much salt or other impurities. Common impurities include chemicals and/or harmful bacteria, such as crypto sporidium. Some solutes are acceptable and even desirable for perceived taste enhancement and to provide needed electrolytes.
Water as a precious resource
:See water resources for information about fresh water supplies.fresh water
Because of the growth of world population and other factors, the availability of drinking water per capita is shrinking. The issue of water shortage can be solved through more production, better distribution and less waste of it. For this reason, water is a strategic resource for many countries. Many battles and wars, such as the Six-Day War in the Middle East, have been fought to gain access to it. Experts predict more trouble ahead because of the world's growing population, increasing contamination through pollution, and global warming.
UNESCO's World Water Development Report (WWDR, 2003) from its World Water Assessment Program indicates that, in the next 20 years, the quantity of water available to everyone is predicted to decrease by 30%. 40% of the world's inhabitants currently have insufficient fresh water for minimal hygiene. More than 2.2 million people died in 2000 from diseases related to the consumption of contaminated water or drought. In 2004, the UKcharityWaterAid reported that a child dies every 15 seconds due to easily preventable water-related diseases.
Some have predicted that clean water will become the "next oil", making Canada, with this resource in abundance, possibly the richest country in the world.
Regulating water distribution
Drinking water is often collected at springs or extracted from artificial borings in the ground, or wells. Building more wells in adequate places is thus a possible way to produce more water assuming the aquifers can supply an adequate flow. Other water sources are the rainwater and river or lake water. This surface water, however, must be purified for human consumption. This may involve removal of undissolved substances, dissolved substances and harmful microbes. Popular methods are filtering with sand which only removes undissolved material while chlorination and boiling kill harmful microbes. Distillation does all three functions. More advanced techniques exist, such as reverse osmosis. Desalination of abundant ocean or seawater is a more expensive solution used in coastal aridclimates.
The distribution of drinking water is done through municipal water systems or as bottled water. Governments in many countries have programs to distribute water to the needy at no charge. Others argue that the market mechanism and free enterprise are best to manage this rare resource, and to finance the boring of wells or the construction of dams and reservoirs.
Reducing waste, that is using drinking water only for human consumption, is another option. In some cities, such as Hong Kong, sea water is extensively used for flushing toilets citywide in order to conserve fresh water resources. Polluting water may be the biggest single misuse of water; to the extent that a pollutant limits other uses of the water, it becomes a waste of the resource, regardless of benefits to the pollutor. Pharmaceuticals consumed by humans often end up in the waterways and can have detrimental effects on aquatic life if they bioaccumulate and if they are not biodegradable.
The impact of water on human culture
Water is considered a purifier in most religions, including Christianity, Islam, Judaism, and Shinto. For instance, baptism in Christian churches is done with water. In addition, a ritual bath in pure water is performed for the dead in many religions including Judaism and Islam. In Islam, the daily Salah can only be done after ablution (Wodoo), that is, washing parts of the body in clean water. In Shinto, water is used in almost all rituals to cleanse a person or an area.
Water is often believed to have spiritual powers. In Celtic mythology, Sulis is the local goddess of thermal springs; in Hinduism, the Ganga is also personified as a goddess. Alternatively, gods can be patrons of particular springs, river or lakes: for example in Greek and Romanmythology, Peneus was a river god, one of the three thousand Oceanids.
The GreekphilosopherEmpedocles held that water is one of the four classical elements along with fire, earth and air, and was regarded as the ylem, or basic stuff of the universe. Water was considered cold and moist. In the theory of the four bodily humours, water was associated with phlegm. Water was also one of the Five Elements in traditional Chinese philosophy, along with earth, fire, wood, and metal.
A common misconception about water is that it is a powerful conductor of electricity. Any electrical properties observable in water are due to the ions of mineral salts and carbon dioxide dissolved in it. Water does self-ionize (two water molecules become one hydroxide anion and one hydronium cation), but only at a very slight, almost immeasurable level. Pure water can also be electrolized into oxygen and hydrogen gases but without any dissolved ions, this is a very slow process and thus very little current is conducted. Many bottled water companies exploit another common misconception, advertising both purity and taste, even though pure water is tasteless.
- [http://www.lsbu.ac.uk/water/phase.html Phase diagrams of water]
- [http://www.publicforuminstitute.org/issues/oceans/index.htm Oceans and Water Issues Page]
- [http://www.greenfacts.org/water-disinfectants/index.htm Scientific Facts on Water disinfectants] A faithful summary by GreenFacts of a leading scientific consensus report on Drinking Water Disinfectants published by the International Programme on Chemical Safety of the WHO.
- [http://www.hkc22.com/residentialwater.html Residential water problems and markets] Study paper from Helmut Kaiser Consultancy
- [http://www.hkc22.com/watermarketsworldwide.html Water markets worldwide] Study paper from Helmut Kaiser Consultancy
- [http://www.worldwaterforum.org/ World Water Forum]
- [http://www.unesco.org/water/wwap/ World Water Assessment Program]
- [http://unesdoc.unesco.org/images/0012/001295/129556e.pdf United Nations' World Water Development Report]
- [http://www.gemswater.org/ United Nations GEMS/Water Programme]
- [http://www.lsbu.ac.uk/water/ Water Structure and Behaviour]
- [http://www.wateraid.org/ WaterAid]
- [http://www.sahra.arizona.edu/newswatch/ SAHRA—Global Water Newswatch]
- [http://www.siwi.org/ Stockholm International Water Institute] (SIWI)
- [http://www.c-win.org/ California Water Impact Network (C-WIN)]
- [http://news.bbc.co.uk/2/hi/science/nature/3752590.stm BBC: The water debate]
- [http://www.geocities.com/tapvsbottled/ Tap Water Vs Bottled Water] - Interesting site providing facts about tap and bottled water.
- [http://www.emagazine.com/september-october_2003/0903feat1.html E the Environmental Magazine piece on bottled water] (Oct 2003).
- [http://www.iapws.org/ International Association for the Properties of Water and Steam]
- [http://ga.water.usgs.gov/edu/watercycle.html US Geological Survey: Comprehensive discussion of the water cycle, in many languages]
- [http://www.dartmouth.edu/~etrnsfer/water.htm Why is water blue?]
- [http://www.water.org.uk/home/resources-and-links/water-for-health/ask-about/adults Water requirements in adults]
- [http://www.hkc22.com/environmentaltechnology.html/ Climate change raises markets for environmental technology, drinking water and clean energies]
:This article is about the god. See 20000 Varuna for the trans-Neptunian object.
In Vedic religion, Varuna is one of the Adityas, and one of the most important Hindu gods, and is chief of the asuras. Varuna is lord of the cosmic rhythm of the celestial spheres. In the pre-Vedic era, he was probably the most supreme god and keeper of order, a god of rain and law who keeps the sun moving. He was omniscient and omnipotent. In the post-Vedic era, his role as sovereign is increasingly taken on by Indra, a process already apparent in the Rig-Veda itself. Together with Mitra, he is the god of the oath. Atharvaveda 4.16 (Shaunakiya, corresponding to Paippalada 5.32) portrays him as omniscient, catching liars in his snares. The stars are his thousand-eyed spies, watching every movement of men. He is often named as forming a unit with Mitra (forming the Dvandva compound, Mitravaruna), and as the heavens was imagined as made from a light and a dark half, Varuna may either correspond or rule over the dark half, or represent the 'dark' side of the Sun as it travels back from West to East during the night.
Varuna is the master of rta, which is the energy that keeps the universe running on time and as it should. Varuna became a lunar deity, depicted in art as a white man wearing golden armor and holding a noose or lasso made from a snake. He rides a sea monster (Makara). He is one of the Ashta-Dikpalas, representing the west.
Varuna is a god of the dead, and can grant immortality. He is perhaps most strongly associated with rain; after Indra took his former position as overlord of the universe, Varuna became the god of oceans and rivers and keeper of the souls of the drowned. He is attended by the nagas.
The name has been connected to the PIE root - wer- or - wel-, meaning "to cover".
As a theonym, it is quite likely of Indo-Iranian age, although no Iranian continuation of the name has survived. The Mitanni names aruna and urvana may refer to the same early Indo-Aryan god. Cognates in other Indo-European languages have been suggested, but remain uncertain.
Notably Uranos, the sky god in Greek mythology, and also Vörnir, a giant of Norse mythology (from - verunyos?), the Slavic godVeles (god), and velnias, the Lithuanian for "devil".
Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. In the case of asteroids, so many have been discovered that many will never be named by their discoverers.
Asteroids
The current system of provisional designation of asteroids has been in place since 1925, and superseded several previous conventions, each of which was rendered obsolete by the increasing numbers of asteroid discoveries.
Historical designations
The first four asteroids were discovered in the early 19th century, after which there was a lengthy gap before the discovery of the fifth. Astronomers initially had no reason to believe that there would be countless thousands of asteroids, and strove to assign a symbol to each new discovery, in the tradition of the symbols used for the major planets. For example, 1 Ceres was assigned a stylized sickle, 2 Pallas a lozenge with a crossed handle, 3 Juno a Venus mirror crowned by a star (later became a star with a crossed handle) and 4 Vesta a sacred fire altar [http://aa.usno.navy.mil/hilton/AsteroidHistory/minorplanets.html].
It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known asteroids was in the tens. Johann Franz Encke introduced a new system in the Berliner Astronomisches Jahrbuch (BAJ) for 1854, published in 1851, in which he used encircled numbers instead of symbols. Encke's system began the numbering with Astrea which was given the number (1) and went through (11) Eunomia, while Ceres, Pallas, Juno and Vesta continued to be denoted by symbols, but in the following year's BAJ, the numbering was changed so that Astraea was number (5).
The new system found popularity among astronomers, and since then, the final designation of an asteroid is a number indicating its order of discovery followed by a name. Even after the adoption of this system, though, several more asteroids received symbols, including 28 Bellona [http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1854AN.....38..143. the whip and lance of Mars' martial sister], 35 Leukothea [http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1855AN.....40..373K an ancient lighthouse] and 37 Fides [http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1856AN.....42..107L a latin cross]. According to [http://www.uni-heidelberg.de/zentral/ari/minor.planets/mp-signs.htm Webster's A Dictionary of the English Language, G. & C. Merriam & Co., Springfield (Ma), USA, p. 1780 (1884)], four more asteroids were also given symbols: 16 Psyche, 17 Thetis, 26 Proserpina, and 29 Amphitrite. However, there is no evidence that these symbols were ever used outside of their initial publication in the Astronomische Nachrichten.
Genesis of the current system
Several different notation and symbolic schemes were used during the latter half of the nineteenth century, but the present form first appeared in the journal Astronomische Nachrichten (AN) in 1911. New numbers were assigned by the AN on receipt of a discovery announcement, and a permanent designation was then assigned once an orbit had been calculated for the new object.
At first, the provisional designation consisted of the year of discovery followed by a letter indicating the sequence of the discovery, but omitting the letter I (sometimes J was omitted instead). Under this scheme, 333 Badenia was initially designated 1892 A, 163 Erigone was 1892 B, etc. In 1893, though, increasing numbers of discoveries forced the revision of the system to use double letters instead, in the sequence AA, AB...AZ, BA and so on. The sequence of double letters was not restarted each year, so that 1894 AQ followed 1893 AP and so on. In 1916, the letters reached ZZ and, rather than starting a series of triple-letter designations, the double-letter series was restarted with 1916 AA.
Later refinements
1925 saw the adoption of a more structured lettering system, in which the provisional designation consisted of the year of discovery, followed by two letters indicating the order of the object's discovery within that year. The first letter indicated the half-month (A=first half of January, B=second half of January, etc), while the second letter indicated the sequence of the discovery. So, the 8th asteroid discovered in the second half of March 1950 would be provisionally designated 1950 FH. If more than 25 objects are discovered in a given half-month (The letter I is not used), the lettering restarts with a subscript 1
Examples
In the year 2004, the first asteroid discovery of January 1 would be named 2004 AA. Then the naming continues to 2004 AZ, followed by 2004 AA1 (partly for technological reasons (ASCII limitations), the subscript may be "flattened out", so that 2004 AA1 is written 2004 AA1). The next discovery is 2004 AB1, then 2004 AC1, etc. Eventually one could get to something like 2004 AA276. Following the end of the half-month, the next asteroid to be discovered would receive the provisional designation 2004 BA.
The large outer solar system object 90377 Sedna had the provisional designation 2003 VB12, meaning it was discovered in the first half of November 2003, and that it was the 302nd object (B->2 + 12 - 25 = 302) discovered during that time. 28978 Ixion, originally 2001 KX76, was discovered in the latter half of May 2001, and was the (X->23 + 76 - 25 = 1923) 1,923rd object discovered during that time.
Comets
The system used previous to 1995 was complex. The year was followed by a space and then a Roman numeral in most cases, but difficulties always arose when an object needed to be placed between previous discoveries. For example, after Comet 1990 III and Comet 1990 IV might be reported, an object discovered in between the discovery dates couldn't be designated Comet 1990 III 1/2. More commonly comets were known by the discover's name and the year.
The system since 1995 follows the provisional designation of asteroids. For comets, the provisional designation consists of the year of discovery, followed by ONE letter (unlike the asteroids with two) indicating the order of the object's discovery within that year. The first letter indicates the half-month (A=first half of January, B=second half of January, etc. skipping I and not reaching Z), while the next character, an on-the-line-digit, indicates the sequence of the discovery. So, the 8th comet discovered in the second half of March 2006 would be given a provisional designation 2006 F8. The tenth comet of late March would thus be 2006 F10.
This method contrasts with asteroids, which use subscripted numerals. If a comet splits, its segments are given the same provisional designation with a suffixed letter A, B, C, ..., Z, a, b, c..., z. One presumes that tracking beyond 52 fragments is unlikely.
If an object is originally found asteroidal, and later develops a cometary tail, it RETAINS its asteroidal designation.
Provisional designations for comets are given condensed or "packed form" in the same manner as asteroids. 2006 F8, if a periodic comet, would be listed in the IAU Minor Planet Database as PK06F080. The last character is purposely a zero, as that allows comet and asteroid designations not to overlap.
Further detail is found at http://cfa-www.harvard.edu/iau/lists/CometResolution.html[http://cfa-www.harvard.edu/iau/lists/CometResolution.html]
Satellites of planets
When satellites are first discovered, they are given provisional designations such as "S/2000 J 11" (the 11th new satellite of Jupiter discovered in 2000) or "S/2003 S 1" (the 1st new satellite of Saturn discovered in 2003). The initial "S/" stands for "satellite", and distinguishes from such prefixes as "D/", "C/", and "P/", used for comets. These designations are sometimes written like "S/2003 S1", dropping the second space.
Asteroid moons
The provisional designation system for asteroid moons follows that established for the satellites of the major planets. The prefix "S/" indicates a natural satellite, and is followed by the year (using the date when the discovery image was acquired, not necessarily the date of discovery). A one letter code identifies the planet (J, S, U, N, P for Jupiter, Saturn, Uranus, Neptune, and Pluto, respectively, and then a number identifies sequentially the observation. For example, Naiad, the innermost moon of Neptune, was at first designated S/1989 N 6. Later, once its existence and orbit were confirmed, it received its full designation, Neptune III Naiad.
With minor planets, the planet letter code is replaced by the minor planet number in parentheses. Thus, the moon of 87 Sylvia, discovered in 1998, was at first designated S/2001 (87) 1, later receiving its permanent designation of (87) Sylvia I Romulus. Where more than one moon has been discovered, Roman numerals specify the discovery sequence, so that Sylvia's second moon is designated (87) Sylvia II Remus.
External links
- [http://aa.usno.navy.mil/hilton/AsteroidHistory/minorplanets.html When Did the Asteroids Become Minor Planets?]
- Benjamin A. Gould, [http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1852AJ......2...80G On the symbolic notation of the asteroids], Astronomical Journal, Vol. 2, Iss. 34, p. 80, 1852 - [http://cfa-www.harvard.edu/iau/info/OldDesDoc.html New- And Old-Style Minor Planet Designations] (Minor Planet Center)
Category:Planetary science
Kâvyâlankâra
Kâvyâlankâra (Meaning: The ornaments of poetry) is the earliest Indian knight's tour is that given on a half-chessboard in the verse work by the Kashmirian poet Rudrata, ascribed to the reign of Sankaravarman, 884 – 903. He also gives a simple boustrophedonal rook tour and a sawtooth elephant tour.
According to H. J. R. Murray's A History of Chess (1913, pp.53-55), our knowledge of this work comes from a commentary by Nami of Guzerat (1069) and analysis by H. Jacobi (1896). The tour of the knight (known as turaga = horse) and the tours by rook and elephant, were apparent
Songs To Wear Pants To
[http://www.songstowearpantsto.com/ Songs To Wear Pants To] is a website run by Andrew Pants, where people can email the site owner with a song request, which can either be requested for free or for a charge (at least $30). Requests are more likely to be fulfilled with a paid request. Requests range from covers of existing songs to creating a song from a set of lyrics to lone sentences with suggested themes. Songs
