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 The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. Approximately 47% of the more than 1,100,000 known minor planetsremain provisionally designated, as hundreds of thousands have been discovered in the last two decades.
The current system of provisional designation of minor planets (asteroids, centaurs and trans-Neptunian objects) 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 It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries.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.
For example, the provisional designation
2016 EK156 stands for the 3910th body identified during 1–15 March 2016:
A(first half of January) to
Y(second half of December), while the letters
Zare 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,
Eindicates the period from March 1 to 15.
Iis 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
156indicates 156 completed cycles (156 cycles × 25 letters = 3900), while
Kis the 10th position in the current cycle. Thus, K156 stands for the 3910th minor planet discovered in a half-month.
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).
K07Tf8Ain the packed form, where "K07" stands for the year 2007, and "f8" for the subscript number 418.
Minor planets discovered during the Palomar–Leiden survey 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:
For example, the asteroid 6344 P-L 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.
The first four minor planets 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 used for the major planets. For example, 1 Ceres was assigned a stylized sickle (⚳), 2 Pallas a stylized lance or spear (⚴), 3 Juno a scepter (⚵), and 4 Vesta 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 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 the morning star and lance of Mars' martial sister, ). According to Webster's A Dictionary of the English Language, four more minor planets 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.35 Leukothea an ancient lighthouse and 37 Fides a Latin cross (
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 and astrological symbol). Three centaurs – 2060 Chiron, 5145 Pholus, and 7066 Nessus – and the other seven large trans-Neptunian dwarf planets – 50000 Quaoar, 90377 Sedna, 90482 Orcus, 136108 Haumea, 136199 Eris, 136472 Makemake, and 225088 Gonggong – 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.
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 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 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 .
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 round 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, 1915 a (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 designations are custom designation given by an observer or discovering observatory prior to the assignment of a provisional designation by the MPC.
letter), digits, numbers and years, as well Roman numerals (
ROM) and Greek letters (
|Algiers Obs.||Alger ||Alger A, Alger CM|
|Alg ||Alg A, Alg CM|
|Alma-Ata||Alma-Ata [Nr.] ||Alma-Ata Nr. 1|
|1952 A1, A1|
|Arequipa||Arequipa ||Arequipa a|
|Areq ||Areq a|
|Arequipa ||Arequipa 17|
|Areq ||Areq 17|
|Belgrade Obs.||1956 x (Beograd), 1956 x|
| Lowell Obs. |
|A ||A0, A7|
|Heidelberg Obs.||Wolf [Nr.] ||Wolf Nr. 18, Wolf 18|
|Wolf ||Wolf u|
|Wolf ||Wolf alpha|
|Heid ||Heid 1, Heid 234|
|Johannesburg Obs.||A, E|
|G ||G 1, G 21|
|T ||T 9, T 16|
|La Plata Obs.||[La Plata] ||La Plata 1951 I, 1951 I|
|[La Plata] ||La Plata 1950 G, 1950 G|
|Lick||[Asteroid] ||Asteroid B, B|
|Mount Wilson Obs.||[Asteroid] ||Asteroid A, A|
| Purple Mountain Obs. |
|P.O. ||P.O. 32, P.O. 189|
|PO ||PO 32, PO 189|
| Crimean Astrophysical Obs. |
|K ||K1, K3423|
|Simeiz Obs.|| SIGMA K ||1942 SIGMA K1, SIGMA K1|
| SIG K ||1942 SIG K1, SIG K1|
|sigma ||sigma 1, sigma 229|
|Taunton Obs.||Taunton ||Taunton 83|
|Tokyo-Mitaka||Tokyo ||Tokyo B|
|Tokyo ||Tokyo b|
|Tokyo ||Tokyo 20|
|Tokyo ||Tokyo 1954 D|
|Turku Obs.||T- ||T-1, T-774|
|Uccle Obs.||p (Uccle), p|
|x2 (Uccle), x2|
|[ ||1945 U 12, U 12|
|Washington||1917 W 15, 1923 W 21|
|Yerkes Obs.||Y.O. ||Y.O. 23|
|YO ||YO 23|
The system used for comets 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 passage, using lower-case letters; thus "Comet Faye" (modern designation 4P/Faye) was both Comet 1881 I (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 1999 RE70 was reclassified as a comet, and because it was discovered by LINEAR, 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.
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).
Comets which do not fulfill the "periodic" requirements receive the "C" prefix (e.g. C/2006 P1, 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.)
When satellites or rings are first discovered, they are given provisional designations such as "S/2000 J 11" (the 11th new satellite of Jupiter discovered in 2000), "S/2005 P 1" (the first new satellite of Pluto discovered in 2005), or "R/2004 S 2" (the second new ring of Saturn 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 comets. These designations are sometimes written as "S/2005 P1", 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, 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".
The Roman numbering system arose with the very first discovery of natural satellites other than Earth's Moon: Galileo referred to the Galilean moons 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. "Jupiter V" 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 " (87) Sylvia I Romulus ".
The provisional designation system for minor planet satellites, such as asteroid moons, 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, 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, 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".
Packed designations are used in online and electronic documents as well as databases.
The Orbit Database (MPCORB) New-style provisional designation.of the Minor Planet Center (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 §
The system of packed provisional minor planet designations:
2014is written as
K14(see tables below)
00is used when there is no following subscript,
99is used for subscript 99,
A0is used for subscript 100, and
A1is used for 101)
Contrary to the new-style system, the letter "i" is used in the packed form both for the year and the numeric suffix. "cycles". This means that 15,500 designations ( = 619×25 + 25) within a half-month can be packed, which is a few times more than the designations assigned monthly in recent years.The compacting system provides upper and lowercase letters to encode up to 619
J95. As it has no subscript number,
00is used as placeholder instead, and directly placed after the half-month letter "X".
J95. Subscript number "1" is padded to
01to maintain the length of 7 characters, and placed after the first letter.
K16. The subscript number "156" exceeds 2 digits and is converted to
F6, (see table below)
K07. The subscript number "418" exceeds 2 digits and is converted to
f8, (see table below)
|Compacting first two digits of year|
|Compacting 3-digit subscript numbers|
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.
J95P01b(i.e. fragment B of comet 1995 P1)
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.
Survey designations used during the Palomar–Leiden Survey (PLS) have a simpler packed form, as for example:
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.
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 above 100,000, a single letter (A–Z and a–z) is used, similar as for the provisional subscript number (also see table above):
Acovers the number range 100,000–109,999
Bcovers the number range 110,000–119,999
acovers the number range 360,000–369,999
zcovers the number range 610,000–619,999
00001encodes 1 Ceres
99999encodes (99999) 1981 FP
A0000encodes 100000 Astronautica, (as
A9999encodes (109999) 2001 SZ62 (as
B0000encodes (110000) 2001 SM63 (as
G3693encodes 163693 Atira (as
Y2843encodes 342843 Davidbowie (as
g0356encodes 420356 Praamzius (as
This system permits compression of numbers up to 619,999 (
z9999). As of November 2021 [update] the list of minor planets already contains 607,011 objects. For minor planets numbered 620,000 or higher, a tilde
"~" will be 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 will allow for the encoding of more than 15 million minor planet numbers. For example:
~0000(620,000 − 620,000 = 0 = 0 × 623 + 0 × 622 + 0 × 621 + 0 × 620)
~000z(620,061 − 620,000 = 61 = 0 × 623 + 0 × 622 + 0 × 621 + 61 × 620)
~AZaz(3,140,113 − 620,000 = 2,520,113 = 10 × 623 + 35 × 622 + 36 × 621 + 61 × 620)
~zzzz(15,396,335 − 620,000 = 14,776,335 = 61 × 623 + 61 × 622 + 61 × 621 + 61 × 620)
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 is
28978 Ixion, provisional designation 2001 KX76, is a large trans-Neptunian object and a possible dwarf planet. It is located in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. Ixion is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. It was discovered in May 2001 by astronomers of the Deep Ecliptic Survey at the Cerro Tololo Inter-American Observatory, and was announced in July 2001. The object is named after the Greek mythological figure Ixion, who was a king of the Lapiths.
The half-month is a calendar subdivision used in astronomy. Each calendar month is separated into two parts:
In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the most interesting objects, and where relevant, features of those objects.
4015 Wilson–Harrington is an active asteroid known both as comet 107P/Wilson–Harrington and as asteroid 4015 Wilson–Harrington. It will pass 0.4 AU (60 million km) from Earth on 20 July 2022 and then pass perihelion on 24 August 2022. It seldom gets brighter than apparent magnitude 16.
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 Working Group for Planetary System Nomenclature (WGPSN).
660 Crescentia is a minor planet orbiting the Sun that was discovered by American astronomer Joel Hastings Metcalf on January 8, 1908. The name may have been inspired by the asteroid's provisional designation 1908 CC. Peter Ting points out that the Rev. Joel Metcalf of Taunton (Massachusetts) discovered six asteroids with unexplained names, though listed in Lutz Schmadel's book. Ting used an on-line planetarium website to help with the location of some of the planets, playing back to the night of discovery. He noticed that there was a crescent moon (33%) low in the western sky and wonders if the Rev. Metcalf could have named the asteroid for the moon. Crescentia would be a very unusual name for a person but not for a phase of the moon.
A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet. Such designation always features a leading number assigned to a body once its orbital path is sufficiently secured. The formal designation is based on the minor planet's provisional designation, which was previously assigned automatically when it had been observed for the first time. Later on, the provisional part of the formal designation may be replaced with a name. Both formal and provisional designations are overseen by the Minor Planet Center (MPC), a branch of the International Astronomical Union.
118401 LINEAR, provisional designation 1999 RE70, is an asteroid and main-belt comet (176P/LINEAR) that was discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) 1-metre telescopes in Socorro, New Mexico on September 7, 1999. (118401) LINEAR was discovered to be cometary on November 26, 2005, by Henry H. Hsieh and David C. Jewitt as part of the Hawaii Trails project using the Gemini North 8-m telescope on Mauna Kea and was confirmed by the University of Hawaii's 2.2-m (88-in) telescope on December 24–27, 2005, and Gemini on December 29, 2005. Observations using the Spitzer Space Telescope have resulted in an estimate of 4.0±0.4 km for the diameter of (118401) LINEAR.
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 International Astronomical Union (IAU) officially used the term minor planet, but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs).
229762 Gǃkúnǁʼhòmdímà (provisional designation 2007 UK126) is a trans-Neptunian object and binary system from the extended scattered disc, located in the outermost region of the Solar System. It was discovered on 19 October 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory in California and measures approximately 600 kilometers (400 miles) in diameter. This medium-sized TNO appears to be representative of a class of mid-sized objects under approximately 1000 km that have not collapsed into fully solid bodies. Its 100-kilometer moon was discovered by Keith Noll, Will Grundy, and colleagues with the Hubble Space Telescope in 2008, and named Gǃòʼé ǃHú.
Gonggong (formally 225088 Gonggong; provisional designation 2007 OR10) is a dwarf planet, a member of the scattered disc beyond Neptune. It has a highly eccentric and inclined orbit during which it ranges from 34–101 astronomical units (5.1–15.1 billion kilometers; 3.2–9.4 billion miles) from the Sun. As of 2019, its distance from the Sun is 88 AU (13.2×109 km; 8.2×109 mi), and it is the sixth-farthest known Solar System object. Gonggong is in a 3:10 orbital resonance with Neptune, in which it completes three orbits around the Sun for every ten orbits completed by Neptune. Gonggong was discovered in July 2007 by American astronomers Megan Schwamb, Michael Brown, and David Rabinowitz at the Palomar Observatory, and the discovery was announced in January 2009.
Quaoar (50000 Quaoar), provisional designation 2002 LM60, is a dwarf planet in the Kuiper belt, a region of icy planetesimals beyond Neptune. A non-resonant object (cubewano), it measures approximately 1,121 km (697 mi) in diameter, about half the diameter of Pluto. The object was discovered by American astronomers Chad Trujillo and Michael Brown at the Palomar Observatory on 4 June 2002. Signs of water ice on the surface of Quaoar have been found, which suggests that cryovolcanism may be occurring on Quaoar. A small amount of methane is present on its surface, which can only be retained by the largest Kuiper belt objects. In February 2007, Weywot, a synchronous moon in orbit around Quaoar, was discovered by Brown. Weywot is measured to be 170 km (110 mi) across. Both objects were named after mythological figures from the Native American Tongva people in Southern California. Quaoar is the Tongva creator deity and Weywot is his son.
A lost comet is one which was not detected during its most recent perihelion passage. This generally happens when data is insufficient to reliably calculate the comet's location or if the solar elongation is unfavorable near perihelion passage. The D/ designation is used for a periodic comet that no longer exists or is deemed to have disappeared.
Comets have been observed for over 2,000 years. During that time, several different systems have been used to assign names to each comet, and as a result many comets have more than one name.
(300163) 2006 VW139, provisional designations 2006 VW139 and P/2006 VW139, as well as periodic cometary number 288P, is a kilometer-sized asteroid from the outer regions of the asteroid belt and the first "binary main-belt comet" ever discovered.
2017 YE5 is a binary pair of asteroids of approximately equal size and mass, each about 0.9 km (0.56 mi) in diameter. Classified as a near-Earth asteroid and potentially hazardous object of the Apollo group, 2017 YE5 was discovered by amateur astronomer Claudine Rinner at the Oukaïmeden Observatory on 21 December 2017. On 21 June 2018, the pair of asteroids passed within 15.5 lunar distances or approximately 6 million km (3.7 million mi) from Earth. During the close encounter, 2017 YE5 was resolved in high detail by concurrent radar observations by the Arecibo and Green Bank observatories, along with individual observations by the Goldstone Solar System Radar. 2017 YE5 is likely an extinct or dormant comet due to its distant elliptical orbit and dark red surface.
2018 VG18 is a distant trans-Neptunian object that was discovered well beyond 100 AU (15 billion km) from the Sun. It was first observed on 10 November 2018 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo during a search for distant trans-Neptunian objects whose orbits might be gravitationally influenced by the hypothetical Planet Nine. They announced their discovery on 17 December 2018 and nicknamed the object "Farout" to emphasize its distance from the Sun.
2018 AG37 (nicknamed FarFarOut) is a distant trans-Neptunian object and centaur that was discovered 132.2 ± 1.5 AU (19.78 ± 0.22 billion km) from the Sun, farther than any other currently observable known object in the Solar System. Imaged in January 2018 during a search for the hypothetical Planet Nine, the confirmation of this object was announced in a press release in February 2021 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo. The object was nicknamed "FarFarOut" to emphasize its distance from the Sun.