# List of minor planets: 20001–21000

The list of minor planets 20001–21000 is a segment of the numbered catalog of small [Solar System](https://www.edgepedia.org/solar-system) bodies maintained by the [Minor Planet Center](https://www.edgepedia.org/minor-planet-center) (MPC), covering the one thousand objects that received permanent numbers 20001 through 21000.

| Key fact | Detail |
|---|---|
| Numbering authority | Permanent numbers are issued sequentially by the Minor Planet Center once an orbit is well determined, typically after observation at four or more oppositions<sup>[1](https://iauarchive.eso.org/public/themes/naming/)</sup> |
| Naming window | The discoverer holds the naming privilege for ten years following the numbering of the object<sup>[1](https://iauarchive.eso.org/public/themes/naming/)</sup> |
| Publication of names | Accepted names become official when published with their citations in the Minor Planet Circulars, issued monthly; since May 2021 citations appear in a bulletin of the IAU Working Group for Small Bodies Nomenclature<sup>[1](https://iauarchive.eso.org/public/themes/naming/)</sup> |
| Discovery era | Most objects in this range were discovered in 1991–1994, during the transition from photographic surveys to CCD-based programs such as Spacewatch<sup>[2](https://catalina.lpl.arizona.edu/faq)</sup> |

## How objects in this range were numbered and named

[A minor](https://www.edgepedia.org/a-minor) planet first receives a provisional designation at discovery, such as 1991 CM for (20001). When follow-up observations allow its position to be predicted reliably far into the future, the MPC assigns a permanent number drawn sequentially from the catalog. The discoverer may then propose a name within ten years of numbering, and the name becomes official when published with its citation.<sup>[1](https://iauarchive.eso.org/public/themes/naming/)</sup>

The numbering of objects in this range reflects the survey technology of the early 1990s. Dedicated photographic surveys such as the Palomar Planet-Crossing Asteroid Survey, founded by Eugene Shoemaker and Eleanor Helin in the early 1970s, were giving way in the 1990s to CCD-based programs like MIT's Lincoln Near-Earth Asteroid Research (LINEAR) and [Spacewatch](https://www.edgepedia.org/spacewatch), which raised discovery rates by two to three orders of magnitude over photographic techniques.<sup>[2](https://catalina.lpl.arizona.edu/faq)</sup>

## Representative entries

The beginning of the range illustrates the mix of discovery sites and discoverers typical of the period.

| Designation | Provisional | Discovery date | Site | Discoverer(s) | Diameter |
|---|---|---|---|---|---|
| 20001 Marinakoren | 1991 CM | February 5, 1991 | Yorii | M. Arai, H. Mori | 23 km |
| 20002 Tillysmith | 1991 EM | March 10, 1991 | Siding Spring | R. H. McNaught | 12 km |
| 20003 Andorfer | 1991 EX<sub>2</sub> | March 11, 1991 | La Silla | H. Debehogne | 3.4 km |
| 20006 Albertus Magnus | 1991 GH<sub>11</sub> | April 11, 1991 | Tautenburg Observatory | F. Börngen | 9.1 km |
| 20007 Marybrown | 1991 LR | June 7, 1991 | Palomar | C. S. Shoemaker, E. M. Shoemaker | 7.1 km |

## Context in the numbered catalog

Numbers in this range sit in the early twenty-thousands of a catalog that has since grown far larger, as computer-driven surveys of the 2000s, including the [Catalina Sky Survey](https://www.edgepedia.org/catalina-sky-survey), LONEOS, NEAT, and [Pan-STARRS](https://www.edgepedia.org/pan-starrs), multiplied discovery rates.<sup>[2](https://catalina.lpl.arizona.edu/faq)</sup> In the MPC's 80-column observation format, numbers in this range are written as zero-padded five-digit fields, so an observation of (20001) is recorded as `20001`.<sup>[3](https://docs.minorplanetcenter.net/mpc-ops-docs/observations/mpc1992-format/)</sup>

## References

1. [Naming of Astronomical Objects, IAU](https://iauarchive.eso.org/public/themes/naming/)
2. [FAQ, Catalina Sky Survey](https://catalina.lpl.arizona.edu/faq)
3. [Format for Astrometric Observations of Comets, Minor Planets and Natural Satellites, MPC Public Documentation Hub](https://docs.minorplanetcenter.net/mpc-ops-docs/observations/mpc1992-format/)

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*Topic: Encyclopedia › Physical world and mathematics › Astronomy › Solar System › Solar System bodies › Minor planet discovery, surveys, and cataloguing*

*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026; Oct 25, 2026 · Last review: Oct 15, 2026*

*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*

License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license