Lost asteroids
Encyclopedia
Lost asteroids or lost planets are asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

s that observers lose track of after discovering. Many early lost asteroids were rediscovered in the 1980s and 1990s, but a number of asteroids and other types of small Solar System bodies
Small Solar System body
A small Solar System body is an object in the Solar System that is neither a planet nor a dwarf planet, nor a satellite of a planet or dwarf planet:...

 continue to be lost. By some definitions, about half of all discovered asteroids are lost because they cannot be found by pointing an appropriate telescope at their predicted location.

Some asteroids and comets discovered in previous decades were "lost" because not enough observational data had been obtained to determine a reliable orbit. Without this information, astronomers would not know where to look for the object at future dates. Occasionally, a "newly discovered" object turns out to be a rediscovery of a previously lost object. This can be determined by calculating the "new" object's orbit backwards and checking its past positions against those previously recorded for the lost object. In the case of lost comets this is especially tricky because of nongravitational forces that can affect their orbits, such as emission of jets of gas from the comet nucleus. However, Brian G. Marsden
Brian G. Marsden
Brian Geoffrey Marsden was a British astronomer born in Cambridge, England, and educated at The Perse School in Cambridge, New College, Oxford and Yale University. Dr...

 has specialized in calculating such nongravitational forces. Notably, he successfully predicted the 1992 return of the once-lost periodic comet Swift–Tuttle.

Lost asteroids can be used for other things as well. For example, observations of asteroids around 20 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

 may provide insights into the Pioneer anomaly
Pioneer anomaly
The Pioneer anomaly or Pioneer effect is the observed deviation from predicted accelerations of the Pioneer 10 and Pioneer 11 spacecraft after they passed about on their trajectories out of the Solar System....

.

20th century recoveries

The number of asteroids that were only observed once and not re-observed grew throughout the 19th and 20th century, but improved telescopes, searches, and detection techniques lead to most of these cases being resolved in the 1970s, 80s, and 90s. There are earlier examples also, such as 132 Aethra
132 Aethra
Discovered by James Craig Watson in 1873, 132 Aethra is an M-type main-belt asteroid. It has a rather eccentric orbit that sometimes brings it closer to the Sun than the planet Mars. It was the first such Mars-crosser asteroid to be identified...

, which was lost between 1873 and 1922.

1970s

1862 Apollo
1862 Apollo
1862 Apollo is a Q-type asteroid, discovered by Karl Reinmuth in 1932, but lost and not recovered until 1973. It is named after the Greek god Apollo....

 is a Q-type asteroid
Q-type asteroid
Q-type asteroids are relatively uncommon inner-belt asteroids with a strong, broad 1 micrometre olivine and pyroxene feature, and a spectral slope that indiciates the presence of metal...

, discovered by Karl Reinmuth in 1932, but lost and not recovered until 1973. Another Apollo asteroid
Apollo asteroid
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth...

 is 2101 Adonis
2101 Adonis
2101 Adonis was one of the first near-Earth asteroids to be discovered. It was discovered by Eugene Delporte in 1936 and named after Adonis, the beautiful youth with whom the goddess Venus fell in love...

, discovered by Eugene Delporte in 1936 and lost until 1977 when it was rediscovered by Charles T. Kowal
Charles T. Kowal
Charles Thomas Kowal was an American astronomer.He discovered two moons of Jupiter: Leda in 1974 and Themisto in 1975, although the latter was lost and not rediscovered until 2000....

. It was also one of the first near-Earth asteroids to be discovered.

1916 Boreas
1916 Boreas
1916 Boreas is an Amor asteroid discovered on September 1, 1953 by Sylvain Julien Victor Arend at the Royal Observatory of Belgium. This asteroid was lost shortly after discovery and only rediscovered in 1974 by Richard Eugene McCrosky , G. Schwartz and JH Bulger based on a predicted position by...

 (1953 RA), an Amor asteroid
Amor asteroid
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars...

, was discovered on 1 September 1953 by Sylvain Julien Victor Arend
Sylvain Julien Victor Arend
Sylvain Julien Victor Arend was a Belgian astronomer born in Robelmont, Luxembourg . His main interest was astrometry.Together with Georges Roland, he discovered the bright comet C/1956 R1...

 at the Royal Observatory of Belgium, and rediscovered in 1974 by Richard Eugene McCrosky, G. Schwartz and JH Bulger based on a predicted position by Brian G. Marsden
Brian G. Marsden
Brian Geoffrey Marsden was a British astronomer born in Cambridge, England, and educated at The Perse School in Cambridge, New College, Oxford and Yale University. Dr...

.

1922 Zulu
1922 Zulu
1922 Zulu is an outer main-belt asteroid discovered on April 25, 1949 by Ernest Leonard Johnson at Johannesburg . It is one of very few asteroids located in the 2 : 1 mean motion resonance with Jupiter...

 (1949 HC) is an outer main-belt asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 discovered on 25 April 1949 by Ernest Leonard Johnson
Ernest Leonard Johnson
Ernest Leonard Johnson was a South African astronomer.He was a former staff member of Union Observatory, retiring in 1956.He discovered a number of asteroids, and several comets, including periodic comet 48P/Johnson.-External references:...

 at Johannesburg (UO). It is one of very few asteroids located in the 2 : 1 mean motion resonance
Orbital resonance
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...

 with Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

. This asteroid was lost shortly after discovery and only rediscovered in 1974 by Richard Eugene McCrosky, Cheng-yuan Shao and JH Bulger based on a predicted position by C. M. Bardwell of the Cincinnati Observatory
Cincinnati Observatory
The Cincinnati Observatory, located in Cincinnati, Ohio on top of Mt. Lookout. It consists of two observatory buildings housing an 11 inch and 16 inch aperture refracting telescope. It is the oldest professional observatory in the United States...

.

1980s & 1990s

L. K. Kristensen at the University of Aarhus
University of Aarhus
Aarhus University , located in the city of Aarhus, Denmark, is Denmark's second oldest and second largest university...

 rediscovered 452 Hamiltonia
452 Hamiltonia
452 Hamiltonia is an asteroid. It was discovered by James Edward Keeler on December 6, 1899, but was then lost until 1987. Its provisional name was 1899 FD. The asteroid is named for Mount Hamilton, the site of Lick Observatory where Keeler was working when he discovered the asteroid.L. K...

 and 1537 Transylvania
1537 Transylvania
1537 Transylvania is a main-belt asteroid discovered on August 27, 1940 by G. Strommer at Budapest.It was a lost asteroid until L. K. Kristensen at Aarhus University rediscovered it along with 452 Hamiltonia along with numerous other small objects in 1981- External links :...

, along with numerous other small objects, in 1981.
At the time these results were published, only nine numbered minor planets remained unobserved since their discoveries: 330 Adalberta
330 Adalberta
330 Adalberta is a small main-belt asteroid.It was discovered by Max Wolf on February 2, 1910, in Heidelberg.An object discovered March 18, 1892, by Max Wolf with provisional designation "1892 X" was named 330 Adalberta, but was lost and never recovered. In 1982, it was determined that the...

, 473 Nolli
473 Nolli
473 Nolli is a rather small asteroid that may be in the Eunomia family. It was discovered by Max Wolf on February 13, 1901, but unusually it remained a "lost asteroid" for many decades, until it was recovered finally in 1987 , 86 years later. Almost nothing is known about its...

, 719 Albert
719 Albert
719 Albert is a Mars-crossing, Amor asteroid; it was the second one discovered after 433 Eros.-Discovery:Discovered in 1911 by Johann Palisa, the asteroid was named after one of the Imperial Observatory in Vienna's major benefactors, Albert Salomon von Rothschild, who had died some months before...

, 724 Hapag
724 Hapag
724 Hapag is a minor planet orbiting the Sun in the asteroid belt. It was found by Johann Palisa in 1911. Its provisional name was 1911 NC.It was a lost asteroid that was rediscovered in 1988 as 1988 VG2 by T. Hioki and N. Kawasato at Okutama, Japan....

, 843 Nicolaia
843 Nicolaia
843 Nicolaia is a minor planet orbiting the Sun. It was a lost asteroid for 65 years before being rediscovered by Heidelberg Astronomisches Rechen-Institut in 1981. -External links:* -External links:...

, 878 Mildred
878 Mildred
878 Mildred is a minor planet in the main belt orbiting the Sun. It is the lowest numbered, and thus the namesake, of the Mildred family of asteroids, a subgroup of the Nysa family...

, 1009 Sirene
1009 Sirene
1009 Sirene is a Mars-crosser asteroid. It was discovered by Karl Wilhelm Reinmuth on October 31, 1923, and named after the mythological Sirens. Its provisional designation was 1923 PE...

, 1026 Ingrid
1026 Ingrid
1026 Ingrid is an asteroid that was discovered by Karl Wilhelm Reinmuth on 13 August 1923 and given the provisional designation 1923 NY. It was named after the niece of German astronomer Albrecht Kahrstedt. This asteroid was lost after its initial discovery and was reidentified in 1986 by Syuichi...

, and 1179 Mally
1179 Mally
1179 Mally is an asteroid that was discovered by Max Wolf on March 19, 1931 and given the provisional designation 1931 FD. It was named after the discoverer's daughter-in-law. It became a lost asteroid after its initial discovery but was rediscovered in 1986 by Lutz D. Schmadel, Richard Martin West...

.

843 Nicolaia was rediscovered at the Heidelberg Astronomisches Rechen-Institut in 1981.

473 Nolli was discovered by Max Wolf
Max Wolf
Maximilian Franz Joseph Cornelius Wolf was a German astronomer and a pioneer in the field of astrophotography...

 on 13 February 1901, but it remained lost for many decades until it was recovered finally in 1987 IAUC 4292, 86 years later.

878 Mildred was originally discovered in 1916 using the 1.5 m (60-inch) Hale Telescope at the Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...

, but was subsequently lost until it was again observed on single nights in 1985 and 1991.

724 Hapag and 719 Albert had first been found by Johann Palisa
Johann Palisa
Johann Palisa was an Austrian astronomer, born in Opava in Austrian Silesia .He was a prolific discoverer of asteroids, discovering 122 in all, from 136 Austria in 1874 to 1073 Gellivara in 1923...

 in 1911. Hapag was given the provisional name 1911 NC, but lost until it was rediscovered in 1988. Due to inaccuracies in its computed orbit, Albert was also lost and not recovered until 2000, when Jeffrey A. Larsen located it using data from the Spacewatch
Spacewatch
Spacewatch is a project at the University of Arizona led by Robert S. McMillan that specializes in the study of minor planets, including various types of asteroids and comets...

 asteroid survey project. At the time of its rediscovery, Albert was the last remaining "lost asteroid" among those assigned numbers (69230 Hermes
69230 Hermes
-External links:* * *...

 was not numbered until 2003).

1009 Sirene
1009 Sirene
1009 Sirene is a Mars-crosser asteroid. It was discovered by Karl Wilhelm Reinmuth on October 31, 1923, and named after the mythological Sirens. Its provisional designation was 1923 PE...

 was recovered in 1982 by J. Gibson using exposures form the 48-inch (120 cm) Schmidt telescope
Samuel Oschin telescope
The Samuel Oschin telescope is a 48-inch aperture Schmidt camera at the Palomar Observatory in northern San Diego County, California. It consists of a 49.75-inch Schmidt corrector plate and a 72-inch mirror. The instrument is strictly a camera; there is no provision for an eyepiece to look...

 at Palomar Observatory
Palomar Observatory
Palomar Observatory is a privately owned observatory located in San Diego County, California, southeast of Pasadena's Mount Wilson Observatory, in the Palomar Mountain Range. At approximately elevation, it is owned and operated by the California Institute of Technology...

, and he revised its ephemeris.

1026 Ingrid
1026 Ingrid
1026 Ingrid is an asteroid that was discovered by Karl Wilhelm Reinmuth on 13 August 1923 and given the provisional designation 1923 NY. It was named after the niece of German astronomer Albrecht Kahrstedt. This asteroid was lost after its initial discovery and was reidentified in 1986 by Syuichi...

 was discovered by Karl Wilhelm Reinmuth
Karl Wilhelm Reinmuth
Karl Wilhelm Reinmuth was a German astronomer.He was a prolific discoverer of asteroids , beginning with 796 Sarita in 1914, working at the Landessternwarte Heidelberg-Königstuhl astronomical observatory on the Königstuhl hill above Heidelberg, Germany from 1912 to 1957.His most notable...

 on 13 August 1923 and given the provisional designation
Provisional designation in astronomy
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...

 1923 NY. It was reidentified in 1986 by Syuichi Nakano
Syuichi Nakano
is a Japanese astronomer. He specializes in the study of comets, in particular calculating their orbits and making predictions about when periodic comets will return for another perihelion approach...

.

1179 Mally
1179 Mally
1179 Mally is an asteroid that was discovered by Max Wolf on March 19, 1931 and given the provisional designation 1931 FD. It was named after the discoverer's daughter-in-law. It became a lost asteroid after its initial discovery but was rediscovered in 1986 by Lutz D. Schmadel, Richard Martin West...

 was discovered by Max Wolf on 19 March 1931 and given the provisional designation 1931 FD. It was rediscovered in 1986 by Lutz D. Schmadel
Lutz D. Schmadel
Lutz D. Schmadel is a German astronomer who works at the Astronomisches Rechen-Institut of the University of Heidelberg.He is a prolific discoverer of asteroids. His special interest is the orbit/course of the asteroids...

, Richard Martin West
Richard Martin West
Richard Martin West is a Danish astronomer working at the European Southern Observatory .He discovered numerous comets, including the spectacular "Comet West" and the periodic comets 76P/West-Kohoutek-Ikemura and 123P/West-Hartley.He also discovered a number of asteroids, including the Trojan...

 and Hans-Emil Schuster
Hans-Emil Schuster
Hans-Emil Schuster is a German astronomer who retired in October 1991. He worked at Hamburg Observatory at Bergedorf and European Southern Observatory , and was former acting director of La Silla Observatory...

.

While studying in Chicago in 1928, Zhang Yuzhe
Zhang Yuzhe
Zhang Yuzhe or Yu-che Chang was a Chinese astronomer who is widely regarded as the father of modern Chinese astronomy....

 discovered an asteroid that was given the provisional designation 1928 UF, and later the number 1125. He named it "China" or "中華" (Zhōnghuá). However, this asteroid was not observed beyond its initial appearance and a precise orbit could not be calculated. In 1957, the Purple Mountain Observatory
Purple Mountain Observatory
Purple Mountain Observatory , also known as Zijinshan Astronomical Observatory, is an astronomical observatory located on the Purple Mountain in Nanjing, China.The long time director of the observatory was Zhang Yuzhe Purple Mountain Observatory , also known as Zijinshan Astronomical Observatory,...

 in China discovered a new asteroid, and with Zhang Yuzhe's agreement the new object was re-assigned the official designation 1125 China
1125 China
1125 China is a main belt asteroid orbiting the Sun. It makes a revolution around the Sun once every 5 years. It was discovered in Purple Mountain Observatory, Nanking, on October 30, 1957...

 in place of the lost 1928 UF. However, in 1986, the newly discovered object was confirmed to be a rediscovery of the original 1928 UF, and this object was named 3789 Zhongguo
3789 Zhongguo
3789 Zhongguo is an outer main-belt asteroid discovered on October 25, 1928 by Y. C. Chang at Williams Bay. It is one of very few asteroids located in the 2 : 1 mean motion resonance with Jupiter. When first discovered in 1928, Zhongguo was named 1125 China. However, as it was not seen again, its...

 (also a name for China).

Asteroid (29075) 1950 DA
(29075) 1950 DA
-External links:* from JPL /...

 was discovered on 23 February 1950 by Carl A. Wirtanen
Carl A. Wirtanen
Carl Alvar Wirtanen was an American astronomer who worked at Lick Observatory.He discovered periodic comet 46P/Wirtanen, as well as eight asteroids, including notably the Apollo asteroid 1950 DA, which may have a non-negligible probability of impacting the earth in the year 2880...

 at Lick Observatory
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...

. It was observed for 17 days and then lost, since not enough observations were made to allow its orbit to be plotted. It was then rediscovered on 31 December 2000. The chance it will impact Earth on 16 March 2880 during its close approach has been estimated as 1 in 300, roughly 50% greater than that for all other such objects combined between now and 2880. It has a diameter of about a kilometer (.6 miles).

7796 Járacimrman
7796 Járacimrman
7796 JáraCimrman is an asteroid orbiting in the main belt of asteroids between Mars and Jupiter. It belongs to the IIa family of asteroids. It cannot approach the Earth nearer than 197 million km.- The discovery :...

 was discovered at Kleť Observatory
Klet Observatory
Kleť Observatory is an astronomical observatory in the Czech Republic. It is situated in South Bohemia, south of the summit of Mount Kleť, near the town of České Budějovice...

 (Czech Republic) on 16 January 1996 by Zdeněk Moravec
Zdenek Moravec
Zdeněk Moravec is a Czech astronomer.He is a prolific discoverer of asteroids.-References:...

 and was designated 1996 BG. It was observed until April 1996 and then in June and July 1997. It was revealed, by precovery
Precovery
Precovery is a term used in astronomy that describes the process of finding the image of an object in old archived images or photographic plates, for the purpose of calculating a more accurate orbit...

, to be a lost asteroid which had previously been observed twice: at the Brera-Merate Observatory
Brera Astronomical Observatory
The Osservatorio Astronomico di Brera is an astronomical observatory. Built in the historic palace of Brera in Milan, Italy in 1764 by Jesuits, the observatory passed in to the hands of the government in 1773 and has passed from government to government control ever since....

 in northern Italy on 12 December 1973 and at Mount Stromlo Observatory
Mount Stromlo Observatory
Mount Stromlo Observatory located just outside of Canberra, Australia, is part of the Research School of Astronomy and Astrophysics at the Australian National University .-History:...

 (near Canberra
Canberra
Canberra is the capital city of Australia. With a population of over 345,000, it is Australia's largest inland city and the eighth-largest city overall. The city is located at the northern end of the Australian Capital Territory , south-west of Sydney, and north-east of Melbourne...

, Australia) on 8 and 9 July 1990.

21st century

2007 WD5
2007 WD5
' is a diameter Apollo class near-Earth object and a Mars-crosser asteroid discovered on November 20, 2007, by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance...

 is a 50 m (164 ft) Apollo-class
Apollo asteroid
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth...

 near-Earth object
Near-Earth object
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to...

 and a Mars-crosser asteroid
Mars-crosser asteroid
A Mars-crosser is an asteroid whose orbit crosses that of Mars. The known numbered Mars-crossers are listed here. They include the two numbered Mars trojans 5261 Eureka and ....

 discovered on 20 November 2007 by Andrea Boattini
Andrea Boattini
Andrea Boattini is an Italian astronomer, a prolific discoverer of asteroids and comets.After developing a growing interest in minor planets, he graduated in 1996 from the University of Bologna with a thesis on near-Earth objects...

 of the Catalina Sky Survey
Catalina Sky Survey
Catalina Sky Survey is a project to discover comets and asteroids, and to search for Near-Earth objects. More specifically, to search for potentially hazardous asteroids , that may pose a threat of impact.-Mission:...

. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance of colliding
Impact event
An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...

 with Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 on 30 January 2008. However, by 9 January 2008 additional observations allowed NASA's Near Earth Object Program (NEOP) to reduce the uncertainty region resulting in only a 1-in-10,000 chance of impact. most likely passed Mars at a distance of 6.5 Mars radii. Due to this relatively small distance and the uncertainty level of the prior observations, the gravitational effects of Mars on its trajectory are unknown and, according to Steven Chesley of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...

 Near Earth Object program, is currently considered "lost". The best fit trajectory had the asteroid passing within 21,000 km of Mars and only 16,000 km from the moon Deimos
Deimos (moon)
Deimos is the smaller and outer of Mars's two moons . It is named after Deimos, a figure representing dread in Greek Mythology. Its systematic designation is '.-Discovery:Deimos was discovered by Asaph Hall, Sr...

.

In the search for various types of near-Earth object
Near-Earth object
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All NEOs have a perihelion distance less than 1.3 AU. They include a few thousand near-Earth asteroids , near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to...

, such as quasi-satellite
Quasi-satellite
A quasi-satellite is an object in a 1:1 orbital resonance with its planet that stays close to the planet over many orbital periods.A quasi-satellite's orbit around the Sun takes exactly the same time as the planet's, but has a different eccentricity , as shown in the diagram on the right...

s and Earth-crosser asteroid
Earth-crosser asteroid
An Earth-crosser is a near-Earth asteroid whose orbit crosses that of Earth as observed from the ecliptic pole of Earth's orbit. The known numbered Earth-crossers are listed here. Those Earth-crossers whose semi-major axes are smaller than Earth's are Aten asteroids; the remaining ones are Apollo...

s, objects that may correspond to some lost sightings include 2006 RH120
2006 RH120
2006 RH120 is a tiny near-Earth asteroid with a diameter of about five metres, which ordinarily orbits the Sun but makes close approaches to the Earth–Moon system every twenty years or so. Occasionally the object temporarily enters Earth orbit through temporary satellite capture...

 or 3753 Cruithne
3753 Cruithne
3753 Cruithne is an asteroid in orbit around the Sun in approximate 1:1 orbital resonance with the Earth. It is a periodic inclusion planetoid orbiting the Sun in an apparent horseshoe orbit. It has been incorrectly called "Earth's second moon", but it is only a quasi-satellite. Cruithne never...

, among others.

In 2007, the object 2007 RR9 was found to be the asteroid 6344 P-L
6344 P-L
6344 P–L is a small Solar System body which was discovered in 1960 by asteroid searchers Tom Gehrels, Ingrid van Houten-Groeneveld, and Cornelis Johannes van Houten. Last seen in 1960, it was thought to be missing but then later rediscovered in 2007 as ' . In other words, it was a lost asteroid...

, lost since 1960. It is a potentially hazardous object
Potentially Hazardous Object
A potentially hazardous object is an asteroid or comet with an orbit such that it has the potential to make close approaches to the Earth and a size large enough to cause significant regional damage in the event of impact....

 and probably a dormant comet, although it was not visibly outgassing at that time.

Errors

Some lost asteroids turn out to be erroneous observations, as in the case of 330 Adalberta. This designation was originally given to 1892 X, but reassigned to A910 CB when 1892 X turned out to be a false positive in the 1980s.

Table

Default list is in increasing order of minor planet number (see List of minor planets). This is really just a small selection of early lost asteroids that were recovered, with some additional examples because the true number of lost asteroids by some definitions is over 150000.
Name(s) Discovered Rediscovered
132 Aethra
132 Aethra
Discovered by James Craig Watson in 1873, 132 Aethra is an M-type main-belt asteroid. It has a rather eccentric orbit that sometimes brings it closer to the Sun than the planet Mars. It was the first such Mars-crosser asteroid to be identified...

 
1873 1922
330 Adalberta (1892 X)
330 Adalberta
330 Adalberta is a small main-belt asteroid.It was discovered by Max Wolf on February 2, 1910, in Heidelberg.An object discovered March 18, 1892, by Max Wolf with provisional designation "1892 X" was named 330 Adalberta, but was lost and never recovered. In 1982, it was determined that the...

 
1892 Error
452 Hamiltonia
452 Hamiltonia
452 Hamiltonia is an asteroid. It was discovered by James Edward Keeler on December 6, 1899, but was then lost until 1987. Its provisional name was 1899 FD. The asteroid is named for Mount Hamilton, the site of Lick Observatory where Keeler was working when he discovered the asteroid.L. K...

 
1899 1987
473 Nolli
473 Nolli
473 Nolli is a rather small asteroid that may be in the Eunomia family. It was discovered by Max Wolf on February 13, 1901, but unusually it remained a "lost asteroid" for many decades, until it was recovered finally in 1987 , 86 years later. Almost nothing is known about its...

 
1901 1987
719 Albert
719 Albert
719 Albert is a Mars-crossing, Amor asteroid; it was the second one discovered after 433 Eros.-Discovery:Discovered in 1911 by Johann Palisa, the asteroid was named after one of the Imperial Observatory in Vienna's major benefactors, Albert Salomon von Rothschild, who had died some months before...

 
1911 2000
724 Hapag
724 Hapag
724 Hapag is a minor planet orbiting the Sun in the asteroid belt. It was found by Johann Palisa in 1911. Its provisional name was 1911 NC.It was a lost asteroid that was rediscovered in 1988 as 1988 VG2 by T. Hioki and N. Kawasato at Okutama, Japan....

 
1911 1988
843 Nicolaia
843 Nicolaia
843 Nicolaia is a minor planet orbiting the Sun. It was a lost asteroid for 65 years before being rediscovered by Heidelberg Astronomisches Rechen-Institut in 1981. -External links:* -External links:...

 
1916 1981
878 Mildred
878 Mildred
878 Mildred is a minor planet in the main belt orbiting the Sun. It is the lowest numbered, and thus the namesake, of the Mildred family of asteroids, a subgroup of the Nysa family...

 
1916 1991
1009 Sirene
1009 Sirene
1009 Sirene is a Mars-crosser asteroid. It was discovered by Karl Wilhelm Reinmuth on October 31, 1923, and named after the mythological Sirens. Its provisional designation was 1923 PE...

 
1923 1982
1026 Ingrid
1026 Ingrid
1026 Ingrid is an asteroid that was discovered by Karl Wilhelm Reinmuth on 13 August 1923 and given the provisional designation 1923 NY. It was named after the niece of German astronomer Albrecht Kahrstedt. This asteroid was lost after its initial discovery and was reidentified in 1986 by Syuichi...

 
1923 1986
1179 Mally
1179 Mally
1179 Mally is an asteroid that was discovered by Max Wolf on March 19, 1931 and given the provisional designation 1931 FD. It was named after the discoverer's daughter-in-law. It became a lost asteroid after its initial discovery but was rediscovered in 1986 by Lutz D. Schmadel, Richard Martin West...

 
1931 1986
1537 Transylvania
1537 Transylvania
1537 Transylvania is a main-belt asteroid discovered on August 27, 1940 by G. Strommer at Budapest.It was a lost asteroid until L. K. Kristensen at Aarhus University rediscovered it along with 452 Hamiltonia along with numerous other small objects in 1981- External links :...

 
1940 1981
1862 Apollo
1862 Apollo
1862 Apollo is a Q-type asteroid, discovered by Karl Reinmuth in 1932, but lost and not recovered until 1973. It is named after the Greek god Apollo....

 
1932 1973
1916 Boreas
1916 Boreas
1916 Boreas is an Amor asteroid discovered on September 1, 1953 by Sylvain Julien Victor Arend at the Royal Observatory of Belgium. This asteroid was lost shortly after discovery and only rediscovered in 1974 by Richard Eugene McCrosky , G. Schwartz and JH Bulger based on a predicted position by...

 
1953 1976
1922 Zulu
1922 Zulu
1922 Zulu is an outer main-belt asteroid discovered on April 25, 1949 by Ernest Leonard Johnson at Johannesburg . It is one of very few asteroids located in the 2 : 1 mean motion resonance with Jupiter...

 
1949 1974
2101 Adonis
2101 Adonis
2101 Adonis was one of the first near-Earth asteroids to be discovered. It was discovered by Eugene Delporte in 1936 and named after Adonis, the beautiful youth with whom the goddess Venus fell in love...

 
1936 1977
3494 Purple Mountain
3494 Purple Mountain
3494 Purple Mountain is a small main belt asteroid. It is not purple; its unusual name comes from the Purple Mountain Observatory in China, where it was rediscovered in 1980...

 
1962 1980
3789 Zhongguo
3789 Zhongguo
3789 Zhongguo is an outer main-belt asteroid discovered on October 25, 1928 by Y. C. Chang at Williams Bay. It is one of very few asteroids located in the 2 : 1 mean motion resonance with Jupiter. When first discovered in 1928, Zhongguo was named 1125 China. However, as it was not seen again, its...

 
1928 1986
6344 P-L
6344 P-L
6344 P–L is a small Solar System body which was discovered in 1960 by asteroid searchers Tom Gehrels, Ingrid van Houten-Groeneveld, and Cornelis Johannes van Houten. Last seen in 1960, it was thought to be missing but then later rediscovered in 2007 as ' . In other words, it was a lost asteroid...

 
1960 2007
7796 Járacimrman
7796 Járacimrman
7796 JáraCimrman is an asteroid orbiting in the main belt of asteroids between Mars and Jupiter. It belongs to the IIa family of asteroids. It cannot approach the Earth nearer than 197 million km.- The discovery :...

 
1973 1996
29075 1950 DA
(29075) 1950 DA
-External links:* from JPL /...

 
1950 2000
69230 Hermes
69230 Hermes
-External links:* * *...

 
1937 2003

Provisional designation only

A very small selection of lost asteroids with provisional designations
Provisional designation in astronomy
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...

.
Name(s) Discovered Rediscovered Note
1991 BA  1991 Lost Passed within a lunar distance
Lunar distance (astronomy)
In astronomy, a lunar distance is a measurement of the distance from the Earth to the Moon. The average distance from Earth to the Moon is 384,400 kilometers...

 of Earth
1993 HD  1993 Lost Near-Earth asteroid
1995 SN55
1995 SN55
', also written as 1995 SN55, is a lost centaur with a perihelion greater than Jupiter and a semi-major axis that may be less than Neptune's. This object could be the largest known centaur.-Size:...

 
1995 Lost May be the largest centaur
2004 PR107  2004 Lost Cubewano; a dwarf-planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...

 candidate
2006 HH123
2006 HH123
', also written as 2006 HH123, is a lost scattered-disc object. With an absolute magnitude of 5.2, it is a dwarf-planet candidate. The preliminary orbital elements as displayed in the infobox are calculated using only three observations over a period of one day, hence its orbit is very poorly known...

 
2006 Lost Scattered-disc object
Scattered disc
The scattered disc is a distant region of the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects. The scattered-disc objects have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater...

; a dwarf-planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...

 candidate
2007 WD5
2007 WD5
' is a diameter Apollo class near-Earth object and a Mars-crosser asteroid discovered on November 20, 2007, by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance...

 
2007 Lost Passed close to Mars

See also

  • Precovery
    Precovery
    Precovery is a term used in astronomy that describes the process of finding the image of an object in old archived images or photographic plates, for the purpose of calculating a more accurate orbit...

  • Earth-grazing fireballs
  • Aten asteroid
    Aten asteroid
    The Aten asteroids are a group of near-Earth asteroids, named after the first of the group to be discovered . They are defined by having semi-major axes of less than one astronomical unit...

  • Lost comet
    Lost comet
    A lost comet is a previously discovered comet that has been missed at its most recent perihelion passage, generally because there is not enough data to reliably calculate the comet's orbit and predict its location....

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