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Provisional designation in astronomy is the
naming convention A naming convention is a convention (generally agreed scheme) for naming things. Conventions differ in their intents, which may include to: * Allow useful information to be deduced from the names based on regularities. For instance, in Manhatta ...
applied to
astronomical object An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...
s immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. Approximately 47% of the more than 1,100,000 known
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
s remain provisionally designated, as hundreds of thousands have been discovered in the last two decades. The modern system is overseen by the
Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...
of the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
. __TOC__


Minor planets

The current system of provisional designation of
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
s (
asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
s,
centaurs A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...
and
trans-Neptunian object A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU). ...
s) has been in place since 1925. It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries. A modern or new-style provisional designation consists of the year of discovery, followed by two letters and, possibly, a suffixed number.


New-style provisional designation

For example, the provisional designation (15760 Albion) stands for the 27th body identified during 16-31 Aug 1992: * 1992 – the first element indicates the year of discovery. * Q – the first letter indicates the half-month of the object's discovery within that year and ranges from A (first half of January) to Y (second half of December), while the letters I and Z are not used ''(see table below)''. The first half is always the 1st through to the 15th of the month, regardless of the numbers of days in the second "half". Thus, Q indicates the period from Aug 16 to 31. * B1 – the second letter and a numerical suffix indicate the order of discovery within that half-month. The first 25 discoveries of the half-month only receive a letter (A to Z) without a suffix, while the letter I is not used (to avoid potential confusions with the digit 1). Because modern techniques typically yield hundreds if not thousands of discoveries per half-month, the subscript number is appended to indicate the number of times that the letters from A to Z have cycled through. The suffix 1 indicates one completed cycle (1 cycle × 25 letters = 25), while B is the 2nd position in the current cycle. Thus, B1 stands for the 27th minor planet discovered in a half-month. * The packed form of is written as . This scheme is now also used retrospectively for pre-1925 discoveries. For these, the first digit of the year is replaced by an A. For example, A801 AA indicates the first object discovered in the first half of January 1801 (
1 Ceres Ceres ( minor-planet designation: 1 Ceres) is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical O ...
).


Further explanations

* During the first half-month of January 2014, the first minor planet identification was assigned the provisional designation . Then the assignment continued to the end of the cycle at , which was in turn followed by the first identification of the second cycle, . The assignment in this second cycle continued with , , ... until , and then was continued with the first item in the third cycle. With the beginning of a new half-month on 16 January 2014, the first letter changed to "B", and the series started with . * An idiosyncrasy of this system is that the second letter is listed before the number, even though the second letter is considered "least-significant". This is in contrast to most of the world's numbering systems. This idiosyncrasy is not seen, however, in the so-called packed form (packed designation). * A packed designation has no spaces. It may also use letters to codify for the designation's year and subscript number. It is frequently used in online and electronic documents. For example, the provisional designation is written as K07Tf8A in the packed form, where "K07" stands for the year 2007, and "f8" for the subscript number 418. *
90377 Sedna Sedna ( minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. Discovered in 2003, the frigid planetoid is one of the reddest known among Solar ...
, a large trans-Neptunian object, had the provisional designation , meaning it was identified in the first half of November 2003 (as indicated by the letter "V"), and that it was the 302nd object identified during that time, as 12 cycles of 25 letters give 300, and the letter "B" is the second position in the current cycle. * Survey designations do not follow the rules for new-style provisional designations. * For technical reasons, such as
ASCII ASCII ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...
limitations, the numerical suffix is not always subscripted, but sometimes "flattened out", so that can also be written as . * A very busy half month was the second half of January 2015 (letter "B"), which saw a total of 14,208 new minor planet identifications . One of the last assignments in this period was and corresponds to the 14,208th position in the sequence.


Survey designations

Minor planets discovered during the
Palomar–Leiden survey The Palomar–Leiden survey (PLS) was a successful astronomical survey to study faint minor planets in a collaboration between the U.S Palomar Observatory and the Dutch Leiden Observatory, and resulted in the discovery of thousands of asteroids ...
including three subsequent Trojan-campaigns, which altogether discovered more than 4,000 asteroids and Jupiter trojans between 1960 and 1977, have custom designations that consist of a number (order in the survey) followed by a space and one of the following identifiers: * P-L  Palomar–Leiden survey (1960–1970) * T-1  Palomar–Leiden Trojan survey (1971) * T-2  Palomar–Leiden Trojan survey (1973) * T-3  Palomar–Leiden Trojan survey (1977) For example, the asteroid
6344 P-L 6344 P-L is an unnumbered, sub-kilometer asteroid and suspected dormant comet, classified as near-Earth object and potentially hazardous asteroid of the Apollo group that was first observed on 24 September 1960, by astronomers and asteroid sea ...
is the 6344th minor planet in the original Palomar–Leiden survey, while the asteroid 4835 T-1 was discovered during the first Trojan-campaign. The majority of these bodies have since been assigned a number and many are already named.


Historical designations

The first four
minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
s 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 minor planets, and strove to assign a symbol to each new discovery, in the tradition of the
symbols A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise different concep ...
used for the major planets. For example,
1 Ceres Ceres ( minor-planet designation: 1 Ceres) is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical O ...
was assigned a stylized sickle (⚳),
2 Pallas Pallas (minor-planet designation: 2 Pallas) is the List of largest asteroids, third-largest asteroid in the Solar System by volume and mass. It is the second asteroid to have been discovered, after 1 Ceres, Ceres, and is likely a remnant ...
a stylized lance or spear (⚴),
3 Juno Juno (minor-planet designation: 3 Juno) is a large asteroid in the asteroid belt. Juno was the third asteroid discovered, in 1804, by German astronomer Karl Harding. It is tied with three other asteroids as the thirteenth largest asteroid, and ...
a scepter (⚵), and
4 Vesta Vesta (minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta (mytho ...
an altar with a sacred fire (). All had various graphic forms, some of considerable complexity. It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known minor planets was in the dozens.
Johann Franz Encke Johann Franz Encke (; 23 September 179126 August 1865) was a German astronomer. Among his activities, he worked on the calculation of the periods of comets and asteroids, measured the distance from the Earth to the Sun, and made observations ...
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 a minor planet is a number indicating its order of discovery followed by a name. Even after the adoption of this system, though, several more minor planets received symbols, including
28 Bellona 28 Bellona is a large main-belt asteroid. It was discovered by German astronomer R. Luther on March 1, 1854, and named after Bellōna, the Roman goddess of war; the name was chosen to mark the beginning of the Crimean War. Its historical symbo ...
the morning star and lance of Mars's martial sister,
35 Leukothea 35 Leukothea is a large, dark asteroid from the asteroid belt. It was discovered by German astronomer Karl Theodor Robert Luther on April 19, 1855, and named after Leukothea, a sea goddess in Greek mythology. Its historical symbol was a ''pha ...
an ancient lighthouse and
37 Fides 37 Fides () is a large main-belt asteroid. It was discovered by German astronomer Karl Theodor Robert Luther on October 5, 1855, and named after Fides, the Roman goddess of loyalty. Fides was the last of the main-belt asteroids to be assigned ...
a Latin cross (). According to Webster's ''A Dictionary of the English Language'', four more minor planets were also given symbols:
16 Psyche 16 Psyche ( ) is a large M-type asteroid, which was discovered by the Italian astronomer Annibale de Gasparis, on 17 March 1852 and named after the Greek goddess Psyche. The prefix "16" signifies that it was the sixteenth minor plane ...
,
17 Thetis 17 Thetis is a stony asteroid from the inner regions of the asteroid belt, approximately 90 kilometers in diameter. It was discovered on 17 April 1852, by German astronomer Robert Luther at Bilk Observatory in Düsseldorf, Germany who deferred ...
,
26 Proserpina 26 Proserpina is a main-belt asteroid discovered by German astronomer R. Luther on May 5, 1853. It is named after the Roman goddess Proserpina, the daughter of Ceres and the Queen of the Underworld. Another main-belt asteroid, 399 Persephone, ...
, and
29 Amphitrite 29 Amphitrite is one of the largest S-type asteroids, approximately in diameter, and probably fifth largest after 15 Eunomia, Eunomia, 3 Juno, Juno, 7 Iris, Iris and 532 Herculina, Herculina. Discovery Amphitrite was discovered by Albert Mart ...
. However, there is no evidence that these symbols were ever used outside of their initial publication in the ''Astronomische Nachrichten''. 134340 Pluto is an exception: it is a high-numbered minor planet that received a graphical symbol with significant astronomical use (♇), because it was considered a major planet on its discovery, and did not receive a minor planet number until 2006. Graphical symbols continue to be used for some minor planets, and assigned for some recently discovered larger ones, mostly by astrologers (see
astronomical symbol Astronomical symbols are abstract pictorial symbols used to represent astronomical objects, theoretical constructs and observational events in Western culture, European astronomy. The earliest forms of these symbols appear in Greek papyrus tex ...
and
astrological symbol Historically, astrological and astronomical symbols have overlapped. Frequently used symbols include signs of the zodiac and classical planets. These originate from medieval Byzantine codices. Their current form is a product of the European Rena ...
). Three
centaurs A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...
2060 Chiron 2060 Chiron is a ringed small Solar System body in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs— ...
, 5145 Pholus, and 7066 Nessus – and the largest trans-Neptunian objects –
50000 Quaoar Quaoar ( minor-planet designation: 50000 Quaoar) is a ringed dwarf planet in the Kuiper Belt, a ring of many icy planetesimals beyond Neptune. It has an elongated ellipsoidal shape with an average diameter of , about half the size of the d ...
,
90377 Sedna Sedna ( minor-planet designation: 90377 Sedna) is a dwarf planet in the outermost reaches of the Solar System, orbiting the Sun far beyond the orbit of Neptune. Discovered in 2003, the frigid planetoid is one of the reddest known among Solar ...
,
90482 Orcus Orcus (minor-planet designation: 90482 Orcus) is a dwarf planet located in the Kuiper belt, with one large moon, Vanth. It has an estimated diameter of , comparable to the Inner Solar System dwarf planet Ceres. The surface of Orcus is relativ ...
, 136108 Haumea,
136199 Eris Eris (minor-planet designation: 136199 Eris) is the most massive and second-largest known dwarf planet in the Solar System. It is a trans-Neptunian object (TNO) in the scattered disk and has a high-eccentricity orbit. Eris was discovered i ...
, 136472 Makemake, and
225088 Gonggong Gonggong (minor-planet designation: 225088 Gonggong) is a dwarf planet and a member of the scattered disc beyond Neptune. It has a highly orbital eccentricity, eccentric and orbital inclination, inclined orbit during which it ranges from from ...
– have relatively standard symbols among astrologers: the symbols for Haumea, Makemake, and Eris have even been occasionally used in astronomy. However, such symbols are generally not in use among astronomers.


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 ''Astronomische Nachrichten'' (''Astronomical Notes''), one of the first international journals in the field of astronomy, was established in 1821 by the German astronomer Heinrich Christian Schumacher. It claims to be the oldest astronomical jour ...
'' (AN) in 1892. 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 (historically, sometimes J was omitted instead). Under this scheme, 333 Badenia was initially designated , 163 Erigone was , 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 followed 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 . Because a considerable amount of time could sometimes elapse between exposing the photographic plates of an astronomical survey and actually spotting a small Solar System object on them (witness the story of Phoebe's discovery), or even between the actual discovery and the delivery of the message (from some far-flung observatory) to the central authority, it became necessary to retrofit discoveries into the sequence — to this day, discoveries are still dated based on when the images were taken, and not on when a human realised they were looking at something new. In the double-letter scheme, this was not generally possible once designations had been assigned in a subsequent year. The scheme used to get around this problem was rather clumsy and used a designation consisting of the year and a lower-case letter in a manner similar to the old provisional-designation scheme for comets. For example, (note that there is a space between the year and the letter to distinguish this designation from the old-style comet designation 1915a, Mellish's first comet of 1915), 1917 b. In 1914 designations of the form year plus Greek letter were used in addition.


Temporary minor planet designations

Temporary designations are custom designations given by an observer or discovering observatory prior to the assignment of a provisional designation by the MPC. These intricate designations were used prior to the
Digital Age The Information Age is a History by period, historical period that began in the mid-20th century. It is characterized by a rapid shift from traditional industries, as established during the Industrial Revolution, to an economy centered on info ...
, when communication was slow or even impossible (e.g. during WWI). The listed temporary designations by observatory or observer use uppercase and lowercase letters (LETTER, letter), digits, numbers and years, as well
Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...
(ROM) and
Greek letters The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It was derived from the earlier Phoenician alphabet, and is the earliest known alphabetic script to systematically write vowels as we ...
(greek).


Comets

The system used for
comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s was complex previous to 1995. Originally, the year was followed by a space and then a Roman numeral (indicating the sequence of discovery) in most cases, but difficulties always arose when an object needed to be placed between previous discoveries. For example, after Comet 1881 III and Comet 1881 IV might be reported, an object discovered in between the discovery dates but reported much later couldn't be designated "Comet 1881 III½". More commonly comets were known by the discoverer's name and the year. An alternate scheme also listed comets in order of time of
perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...
passage, using lower-case letters; thus "Comet Faye" (modern designation
4P/Faye Comet 4P/Faye (also known as Faye's Comet or Comet Faye) is a periodic Jupiter-family comet discovered in November 1843 by Hervé Faye at the Royal Observatory in Paris. Its most recent perihelia (closest approaches to the Sun) were on No ...
) was both
Comet 1881 I Comet 4P/Faye (also known as Faye's Comet or Comet Faye) is a periodic Jupiter-family comet discovered in November 1843 by Hervé Faye at the Royal Observatory in Paris. Its most recent perihelia (closest approaches to the Sun) were on No ...
(first comet to pass perihelion in 1881) and Comet 1880c (third comet to be discovered in 1880). The system since 1995 is similar to the provisional designation of minor planets. For comets, the provisional designation consists of the year of discovery, a space, ''one'' letter (unlike the minor planets with two) indicating the half-month of discovery within that year (A=first half of January, B=second half of January, etc. skipping I (to avoid confusion with the number 1 or the numeral I) and not reaching Z), and finally a number (not subscripted as with minor planets), indicating the sequence of discovery within the half-month. Thus, the eighth comet discovered in the second half of March 2006 would be given the provisional designation 2006 F8, whilst the tenth comet of late March would be 2006 F10. If a comet splits, its segments are given the same provisional designation with a suffixed letter A, B, C, ..., Z, AA, AB, AC... If an object is originally found asteroidal, and later develops a cometary tail, it retains its asteroidal designation. For example, minor planet 1954 PC turned out to be Comet Faye, and we thus have "4P/1954 PC" as one of the designations of said comet. Similarly, minor planet was reclassified as a comet, and because it was discovered by
LINEAR In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a '' function'' (or '' mapping''); * linearity of a '' polynomial''. An example of a linear function is the function defined by f(x) ...
, it is now known as 176P/LINEAR (LINEAR 52) ''and'' (118401) LINEAR. Provisional designations for comets are given condensed or "packed form" in the same manner as minor planets. 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 minor planet designations not to overlap.


Periodic comets

Comets are assigned one of four possible prefixes as a rough classification. The prefix "P" (as in, for example, P/1997 C1, a.k.a. Comet Gehrels 4) designates a "periodic comet", one which has an orbital period of less than 200 years or which has been observed during more than a single perihelion passage (e.g. 153P/Ikeya-Zhang, whose period is 367 years). They receive a permanent number prefix after their second observed perihelion passage ''(see
List of periodic comets Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes us ...
)''.


Non-periodic comets

Comets which do not fulfill the "periodic" requirements receive the "C" prefix (e.g.
C/2006 P1 Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on 7 August 2006 by British-Australian astronomer Robert H. McNaught using the Uppsala Southern Schmidt Telescope. I ...
, the Great Comet of 2007). Comets initially labeled as "non-periodic" may, however, switch to "P" if they later fulfill the requirements. Comets which have been lost or have disintegrated are prefixed "D" (e.g. D/1993 F2, Comet Shoemaker-Levy 9). Finally, comets for which no reliable orbit could be calculated, but are known from historical records, are prefixed "X" as in, for example, X/1106 C1. ''(Also see List of non-periodic comets and
List of hyperbolic comets This is a list of parabolic and hyperbolic comets in the Solar System. Many of these comets may come from the Oort cloud, or perhaps even have interstellar origin. The Oort Cloud is not gravitationally attracted enough to the Sun to form into ...
.)''


Satellites and rings of planets

When satellites or rings are first discovered, they are given provisional designations such as "" (the 11th new satellite of
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
discovered in 2000), "" (the first new satellite of
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
discovered in 2005), or "" (the second new ring of
Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
discovered in 2004). The initial "S/" or "R/" stands for "satellite" or "ring", respectively, distinguishing the designation from the prefixes "C/", "D/", "P/", and "X/" used for
comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
s. These designations are sometimes written as "", dropping the second space. The prefix "S/" indicates a natural satellite, and is followed by a year (using the year when the discovery image was acquired, not necessarily the date of discovery). A one-letter code written in upper case identifies the planet such as J and S for Jupiter and Saturn, respectively ''(see list of one-letter abbreviations)'', and then a number identifies sequentially the observation. For example,
Naiad In Greek mythology, the naiads (; ), sometimes also hydriads, are a type of female spirit, or nymph, presiding over fountains, wells, springs, streams, brooks and other bodies of fresh water. They are distinct from river gods, who embodied ...
, the innermost moon of Neptune, was at first designated "". Later, once its existence and orbit were confirmed, it received its full designation, "". The Roman numbering system arose with the very first discovery of natural satellites other than Earth's Moon:
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642), commonly referred to as Galileo Galilei ( , , ) or mononymously as Galileo, was an Italian astronomer, physicist and engineer, sometimes described as a poly ...
referred to the
Galilean moons The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter. They are, in descending-size order, Ganymede (moon), Ganymede, Callisto (moon), Callisto, Io (moon), Io, and Europa (moon), Europa. They are the most apparent m ...
as I through IV (counting from Jupiter outward), in part to spite his rival Simon Marius, who had proposed the names now adopted. Similar numbering schemes naturally arose with the discovery of moons around Saturn and Uranus. Although the numbers initially designated the moons in orbital sequence, new discoveries soon failed to conform with this scheme (e.g. "" is Amalthea, which orbits closer to Jupiter than does Io). The unstated convention then became, at the close of the 19th century, that the numbers more or less reflected the order of discovery, except for prior historical exceptions ''(see the Timeline of discovery of Solar System planets and their natural satellites)''. The convention has been extended to natural satellites of minor planets, such as "".


Moons of minor planets

The provisional designation system for minor planet satellites, such as
asteroid moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...
s, follows that established for the satellites of the major planets. With minor planets, the planet letter code is replaced by the minor planet number in parentheses. Thus, the first observed moon of
87 Sylvia 87 Sylvia is one of the largest asteroids (approximately tied for 7th place, to within measurement uncertainties). It is the parent body of the Sylvia family and member of Cybele group located beyond the main asteroid belt (see minor-planet ...
, discovered in 2001, 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. Since Pluto was reclassified in 2006, discoveries of Plutonian moons since then follow the minor-planet system: thus Nix and Hydra, discovered in 2005, were S/2005 P 2 and S/2005 P 1, but Kerberos and
Styx In Greek mythology, Styx (; ; lit. "Shuddering"), also called the River Styx, is a goddess and one of the rivers of the Greek Underworld. Her parents were the Titans Oceanus and Tethys, and she was the wife of the Titan Pallas and the moth ...
, discovered in 2011 and 2012 respectively, were S/2011 (134340) 1 and S/2012 (134340) 1. That said, there has been some unofficial use of the formats "S/2011 P 1" and "S/2012 P 1". Scott S. Sheppard
Pluto Moons
/ref>''New Horizons'' news, Johns Hopkins University Applied Physics Laboratory
"Fourth Moon Adds to Pluto's Appeal"
, 20 July 2011


Packed designation

Packed designations are used in online and electronic documents as well as databases.


Packed minor planet designation

The Orbit Database (MPCORB) of the
Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Funct ...
(MPC) uses the "packed form" to refer to all provisionally designated minor planets. The idiosyncrasy found in the new-style provisional designations, no longer exists in this packed-notation system, as the second letter is now listed ''after'' the subscript number, or its equivalent 2-digit code. For an introduction on provisional minor planet designations in the "un-packed" form, see .


Provisional packed designations

The system of packed provisional minor planet designations: * uses exactly 7 characters with no spaces for all designations * compacts 4 digit years to a 3-character code, e.g. 2014 is written as K14 ''(see tables below)'' * converts all subscript numbers to a 2-character code (00 is used when there is no following subscript, 99 is used for subscript 99, A0 is used for subscript 100, and A1 is used for 101) * the packed 2 character subscript code is placed ''between'' the half-month letter and the second (discovery order) letter (e.g. has discovery order K so the last three characters for its packed form are A2K) Contrary to the new-style system, the letter "i" is used in the packed form both for the year and the numeric suffix. The compacting system provides upper and lowercase letters to encode up to 619 "cycles". This means that 15,500 designations () within a half-month can be packed, which is a few times more than the designations assigned monthly in recent years. ; Examples: # is written as J95X00A # is written as J95X01L # is written as K16EF6K # is written as K07Tf8A ; Description # The year 1995 is compacted to J95. As it has no subscript number, 00 is used as placeholder instead, and directly placed after the half-month letter "X". # The year 1995 is compacted to J95. Subscript number "1" is padded to 01 to maintain the length of 7 characters, and placed after the first letter. # The year 2016 is compacted to K16. The subscript number "156" exceeds 2 digits and is converted to F6, ''(see table below)'' # The year 2007 is compacted to K07. The subscript number "418" exceeds 2 digits and is converted to f8, ''(see table below)'' ; Conversion tables Comets follow the minor-planet scheme for their first four characters. The fifth and sixth characters encode the number. The seventh character is usually 0, unless it is a component of a split comet, in which case it encodes in lowercase the letter of the fragment. ; Examples: # 1995 A1 is written as J95A010 # 1995 P1-B is written as J95P01b (i.e. fragment B of comet ) # 2088 A103 is written as K88AA30 (as the subscript number exceeds two digits and is converted according to the above table). There is also an extended form that adds five characters to the front. The fifth character is one of "C", "D", "P", or "X", according to the status of the comet. If the comet is periodic, then the first four characters are the periodic-comet number (padded to the left with zeroes); otherwise, they are blank. Natural satellites use the format for comets, except that the last column is always 0.


Packed survey designations

Survey designations used during the
Palomar–Leiden Survey The Palomar–Leiden survey (PLS) was a successful astronomical survey to study faint minor planets in a collaboration between the U.S Palomar Observatory and the Dutch Leiden Observatory, and resulted in the discovery of thousands of asteroids ...
(PLS) have a simpler packed form, as for example: * is written as PLS6344 * is written as T1S4835 * is written as T2S1010 * is written as T3S4101 Note that the survey designations are distinguished from provisional designations by having the letter S in the third character, which contains a decimal digit in provisional designations and permanent numbers.


Permanent packed designations

A packed form for permanent designations also exists (these are numbered minor planets, with or without a name). In this case, only the designation's number is used and converted to a 5-character string. The rest of the permanent designation is ignored. Minor planet numbers below 100,000 are simply zero-padded to 5 digits from the left side. For minor planets between 100,000 and 619,999 inclusive, a single letter (A–Z and a–z) is used, similar as for the provisional subscript number ''(also see table above)'': * A covers the number range 100,000–109,999 * B covers the number range 110,000–119,999 * a covers the number range 360,000–369,999 * z covers the number range 610,000–619,999 ; Examples: * 00001 encodes
1 Ceres Ceres ( minor-planet designation: 1 Ceres) is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical O ...
* 99999 encodes * A0000 encodes 100000 Astronautica, () * A9999 encodes () * B0000 encodes () * G3693 encodes 163693 Atira () * Y2843 encodes 342843 Davidbowie () * g0356 encodes 420356 Praamzius () * z9999 encodes () For minor planets numbered 620,000 or higher, a tilde "~" is used as the first character. The subsequent 4 characters encoded in Base62 (using 0–9, then A–Z, and a–z, in this specific order) are used to store the difference of the object's number minus 620,000. This extended system allows for the encoding of more than 15 million minor planet numbers. For example: * is represented as ~0000 ( * is represented as ~000z ( * (3140113) will be represented as ~AZaz ( * (15396335) will be represented as ~zzzz ( For comets, permanent designations only apply to periodic comets that are seen to return. The first four characters are the number of the comet (left-padded with zeroes). The fifth character is "P", unless the periodic comet is lost or defunct, in which case it is "D". For natural satellites, permanent packed designations take the form of the planet letter, then three digits containing the converted Roman numeral (left-padded with zeroes), and finally an "S". For example, Jupiter XIII Leda is J013S, and Neptune II
Nereid In Greek mythology, the Nereids or Nereides ( ; ; , also Νημερτές) are sea nymphs (female spirits of sea waters), the 50 daughters of the ' Old Man of the Sea' Nereus and the Oceanid Doris, sisters to their brother Nerites. They ofte ...
is N002S.


See also

*
Minor-planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...
*
Naming of moons The naming of moons has been the responsibility of the International Astronomical Union's committee for Planetary System Nomenclature since 1973. That committee is known today as the Planetary nomenclature, Working Group for Planetary System Nomenc ...


References

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External links


New- And Old-Style Minor Planet Designations
(Minor Planet Center) {{DEFAULTSORT:Provisional Designation In Astronomy Astronomical nomenclature Comets Minor planets Moons * * *