# 9000 Hal

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This article is about the real-life asteroid. For the fictional computer in *2001: A Space Odyssey*, see [HAL 9000](/source/HAL_9000).

**9000 Hal**, provisional designation , is a stony background [asteroid](/source/Asteroid) and [slow rotator](/source/List_of_slow_rotators_(minor_planets)) from the inner regions of the [asteroid belt](/source/Asteroid_belt), approximately 4 kilometers (2.5 miles) in diameter. It was discovered on 3 May 1981, by American astronomer [Edward Bowell](/source/Edward_Bowell) at Lowell's [Anderson Mesa Station](/source/Anderson_Mesa_Station) near Flagstaff, Arizona, in the United States.[1] The likely elongated [S-type asteroid](/source/S-type_asteroid) has an exceptionally long [rotation period](/source/Rotation_period) of 908 hours.[4] It was named after the fictional supercomputer [HAL 9000](/source/HAL_9000), featured in the 1968 film *[2001: A Space Odyssey](/source/2001:_A_Space_Odyssey_(film))*.[1]

## Orbit and classification

Hal is a non-[family](/source/Asteroid_family) asteroid of the main belt's [background population](/source/Background_asteroid) when applying the [hierarchical clustering method](/source/Hierarchical_Clustering_Method_(asteroids)) to its [proper orbital elements](/source/Proper_orbital_elements).[3] Based on osculating Keplerian [orbital elements](/source/Orbital_elements), the asteroid has also been classified as a member of the [Flora family](/source/Flora_family) ([402](/source/FIN_tbl#402)), a giant [asteroid family](/source/Asteroid_family) and the largest family of stony asteroids in the main-belt.[4]

Hal orbits the Sun in the [inner](/source/Kirkwood_gap) asteroid belt at a distance of 1.8–2.7 [AU](/source/Astronomical_unit) once every 3 years and 4 months (1,216 days; [semi-major axis](/source/Semi-major_axis) of 2.23 AU). Its orbit has an [eccentricity](/source/Orbital_eccentricity) of 0.21 and an [inclination](/source/Orbital_inclination) of 6[°](/source/Degree_(angle)) with respect to the [ecliptic](/source/Ecliptic).[2] The asteroid was first observed as at [Crimea–Nauchnij](/source/Crimea%E2%80%93Nauchnij) in November 1975. The body's [observation arc](/source/Observation_arc) begins with its official discovery observation at Anderson Mesa in May 1981.[1]

## Physical characteristics

Hal is an assumed stony [S-type asteroid](/source/S-type_asteroid), based on the *Collaborative Asteroid Lightcurve Link'*s (CALL) classification into the Flora family.[4]

### Rotation period

In August 2008, a rotational [lightcurve](/source/Lightcurve) of Hal was obtained from [photometric](/source/Photometry_(astronomy)) observations by Slovak astronomers [Adrián Galád](/source/Adri%C3%A1n_Gal%C3%A1d), [Jozef Világi](/source/Jozef_Vil%C3%A1gi), [Leonard Kornoš](/source/Leonard_Korno%C5%A1) and [Štefan Gajdoš](/source/%C5%A0tefan_Gajdo%C5%A1) at [Modra Observatory](/source/Modra_Observatory).[9] Lightcurve analysis gave an exceptionally long [rotation period](/source/Rotation_period) of 908 hours with a high brightness variation of 0.9 [magnitude](/source/Magnitude_(astronomy)) ([U=2+](/source/LCDB_quality_code)). This makes Hal [one of the slowest rotators](/source/List_of_slow_rotators_(minor_planets)#Periods_between_500_and_1000_hours) known to exist. In addition, the body's high brightness amplitude is indicative of a non-spherical shape.

An alternative measurement by French amateur astronomers [Pierre Antonini](/source/Pierre_Antonini) and [René Roy](/source/Ren%C3%A9_Roy_(astronomer)) gave a much shorter period of 22.68 hours.[8] The result, however, is considered of poor quality by CALL ([U=1](/source/LCDB_quality_code)).[4]

### Diameter and albedo

According to the survey carried out by the [NEOWISE](/source/NEOWISE) mission of NASA's [Wide-field Infrared Survey Explorer](/source/Wide-field_Infrared_Survey_Explorer), Hal measures between 3.61 and 4.134 kilometers in diameter and its surface has an [albedo](/source/Astronomical_albedo) between 0.26 and 0.375.[5][6][7] CALL assumes an albedo of 0.24 – derived from [8 Flora](/source/8_Flora), the Flora family's [parent body](/source/Parent_body) – and calculates a diameter of 4.11 kilometers based on an [absolute magnitude](/source/Absolute_magnitude) of 14.1.[4]

## Naming

This [minor planet](/source/Minor_planet) was named after the fictional and homicidal supercomputer [HAL 9000](/source/HAL_9000), featured in both [Arthur C. Clarke](/source/Arthur_C._Clarke)'s novel and [Stanley Kubrick](/source/Stanley_Kubrick)'s film *[2001: A Space Odyssey](/source/2001:_A_Space_Odyssey_(film))* (1968).[1] HAL stands for *Heuristically programmed Algorithmic computer*. It is one of the best-known [artificial intelligence](/source/Artificial_intelligence) characters in modern movies. The official naming citation was published by the [Minor Planet Center](/source/Minor_Planet_Center) on 4 May 1999 ([M.P.C.](/source/Minor_Planet_Circulars) 34628).[11] The asteroid [4923 Clarke](/source/4923_Clarke) and [10221 Kubrick](/source/10221_Kubrick) were named after the writer and film director, respectively.

## References

1. ["9000 Hal (1981 JO)"](https://www.minorplanetcenter.net/db_search/show_object?object_id=9000). *Minor Planet Center*. Retrieved 16 May 2018.

1. ["JPL Small-Body Database Browser: 9000 Hal (1981 JO)"](https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009000) (2017-05-01 last obs.). [Jet Propulsion Laboratory](/source/Jet_Propulsion_Laboratory). Retrieved 16 May 2018.

1. ["Asteroid 9000 Hal"](https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=9000%20Hal). *Small Bodies Data Ferret*. Retrieved 15 May 2018.

1. No. 9000. Retrieved 16 May 2018.

1. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T. et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". *The Astronomical Journal*. **152** (3): 12. [arXiv:1606.08923](https://arxiv.org/abs/1606.08923). [Bibcode:2016AJ....152...63N](https://ui.adsabs.harvard.edu/abs/2016AJ....152...63N). [doi:10.3847/0004-6256/152/3/63](https://doi.org/10.3847/0004-6256/152/3/63)

1. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J. et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". *The Astrophysical Journal*. **741** (2): 20. [arXiv:1109.4096](https://arxiv.org/abs/1109.4096). [Bibcode:2011ApJ...741...68M](https://ui.adsabs.harvard.edu/abs/2011ApJ...741...68M). [doi:10.1088/0004-637X/741/2/68](https://doi.org/10.1088/0004-637X/741/2/68). [S2CID 118745497](https://api.semanticscholar.org/CorpusID:118745497)

1. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D. et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". *The Astrophysical Journal*. **741** (2): 25. [arXiv:1109.6407](https://arxiv.org/abs/1109.6407). [Bibcode:2011ApJ...741...90M](https://ui.adsabs.harvard.edu/abs/2011ApJ...741...90M). [doi:10.1088/0004-637X/741/2/90](https://doi.org/10.1088/0004-637X/741/2/90). [S2CID 35447010](https://api.semanticscholar.org/CorpusID:35447010) ([catalog](http://iopscience.iop.org/0004-637X/741/2/68/fulltext/apj398969t1_mrt.txt))

1. Behrend, Raoul. ["Asteroids and comets rotation curves – (9000) Hal"](http://obswww.unige.ch/~behrend/page5cou.html#009000). Geneva Observatory. Retrieved 16 May 2018.

1. Galad, Adrian; Vilagi, Jozef; Kornos, Leonard; Gajdos, Stefan (July 2009). "Relative Photometry of Nine Asteroids from Modra". *The Minor Planet Bulletin*. **36** (3): 116–118. [Bibcode:2009MPBu...36..116G](https://ui.adsabs.harvard.edu/abs/2009MPBu...36..116G). [ISSN 1052-8091](https://www.worldcat.org/issn/1052-8091)

1. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". *Icarus*. **261**: 34–47. [arXiv:1506.00762](https://arxiv.org/abs/1506.00762). [Bibcode:2015Icar..261...34V](https://ui.adsabs.harvard.edu/abs/2015Icar..261...34V). [doi:10.1016/j.icarus.2015.08.007](https://doi.org/10.1016/j.icarus.2015.08.007). [S2CID 53493339](https://api.semanticscholar.org/CorpusID:53493339)

1. ["MPC/MPO/MPS Archive"](https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html). *Minor Planet Center*. Retrieved 16 May 2018.

## External links

- [Asteroid Lightcurve Database (LCDB)](http://www.minorplanet.info/PHP/lcdbsummaryquery.php), query form ([info](http://www.minorplanet.info/lightcurvedatabase.html) [Archived](https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html) 16 December 2017 at the Wayback Machine)
- [Dictionary of Minor Planet Names](https://books.google.com/books?id=aeAg1X7afOoC&pg), Google books
- [Asteroids and comets rotation curves, CdR](http://obswww.unige.ch/~behrend/page_cou.html) – Observatoire de Genève, Raoul Behrend
- [Discovery Circumstances: Numbered Minor Planets (5001)-(10000)](https://www.minorplanetcenter.net/iau/lists/NumberedMPs005001.html) – Minor Planet Center

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Adapted from the Wikipedia article [9000 Hal](https://en.wikipedia.org/wiki/9000_Hal) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/9000_Hal?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.