{{Short description|Main-belt asteroid}} {{About|the real-life asteroid|the fictional computer in ''2001: A Space Odyssey''|HAL 9000}} {{Use dmy dates|date=May 2018}} {{Infobox planet | minorplanet = yes | name = 9000 Hal | background = #D6D6D6 | image = | image_size = | caption = | discovery_ref = <ref name="MPC-object" /> | discoverer = E. Bowell | discovery_site = Anderson Mesa Stn. | discovered = 3 May 1981 | mpc_name = (9000) Hal | alt_names = 1981 JO{{·}}{{mp|1975 VH|3}}<br />{{mp|1981 JJ|3}}{{·}}{{mp|1995 US|3}} | pronounced = {{IPAc-en|'|h|æ|l}} | named_after = HAL 9000<ref name="MPC-object" /><br />{{small|(Fictional supercomputer)}} | mp_category = main-belt<ref name="MPC-object" /><ref name="jpldata" />{{·}}{{small|(inner)}}<br />{{nowrap|background<ref name="Ferret" />{{·}}Flora<ref name="lcdb" />}} | orbit_ref = <ref name="jpldata" /> | epoch = 23 March 2018 (JD 2458200.5) | uncertainty = 0 | observation_arc = 41.49 yr (15,156 d) | aphelion = 2.6955 AU | perihelion = 1.7648 AU | semimajor = 2.2301 AU | eccentricity = 0.2087 | period = 3.33 yr (1,216 d) | mean_anomaly = 328.38° | mean_motion = {{Deg2DMS|0.2959|sup=ms}} / day | inclination = 6.2618° | asc_node = 226.61° | arg_peri = 79.871° | mean_diameter = {{val|3.61|0.78|ul=km}}<ref name="Nugent-2016" /><br />{{val|4.11|u=km}} {{small|(calculated)}}<ref name="lcdb" /><br />{{val|4.134|0.935|u=km}}<ref name="Masiero-2011" /><ref name="WISE" /> | rotation = {{val|22.68|0.02|ul=h}} {{small|(poor)}}<ref name="geneva-obs" /><br />{{val|908|u=h}}<ref name="Galad-2009c" /> | albedo = {{val|0.24}} {{small|(assumed)}}<ref name="lcdb" /><br />{{val|0.26|0.13}}<ref name="Nugent-2016" /><br />{{val|0.375|0.184}}<ref name="Masiero-2011" /><ref name="WISE" /> | spectral_type = S {{small|(assumed)}}<ref name="lcdb" /> | abs_magnitude = 13.6<ref name="WISE" /><br />14.0<ref name="jpldata" /><br />14.1<ref name="lcdb" /><br />{{val|14.35|0.66}}<ref name="Veres-2015" /><br />14.42<ref name="Nugent-2016" /> }}
'''9000 Hal''', provisional designation {{mp|1981 JO}}, is a stony background asteroid and slow rotator from the inner regions of the asteroid belt, approximately {{convert|4|km|mi|abbr=off|sigfig=2|sp=us}} in diameter. It was discovered on 3 May 1981, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, in the United States.<ref name="MPC-object" /> The likely elongated S-type asteroid has an exceptionally long rotation period of 908 hours.<ref name="lcdb" /> It was named after the fictional supercomputer HAL 9000, featured in the 1968 film ''2001: A Space Odyssey''.<ref name="MPC-object" />
== Orbit and classification ==
Hal is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.<ref name="Ferret" /> Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family ({{small|402}}), a giant asteroid family and the largest family of stony asteroids in the main-belt.<ref name="lcdb" />
Hal orbits the Sun in the inner asteroid belt at a distance of 1.8–2.7 AU once every 3 years and 4 months (1,216 days; semi-major axis of 2.23 AU). Its orbit has an eccentricity of 0.21 and an inclination of 6° with respect to the ecliptic.<ref name="jpldata" /> The asteroid was first observed as {{mp|1975 VH|3}} at Crimea–Nauchnij in November 1975. The body's observation arc begins with its official discovery observation at Anderson Mesa in May 1981.<ref name="MPC-object" />
== Physical characteristics ==
Hal is an assumed stony S-type asteroid, based on the ''Collaborative Asteroid Lightcurve Link''{{'s}} (CALL) classification into the Flora family.<ref name="lcdb" />
=== Rotation period ===
In August 2008, a rotational lightcurve of Hal was obtained from photometric observations by Slovak astronomers Adrián Galád, Jozef Világi, Leonard Kornoš and Štefan Gajdoš at Modra Observatory.<ref name="Galad-2009c" /> Lightcurve analysis gave an exceptionally long rotation period of 908 hours with a high brightness variation of 0.9 magnitude ({{small|U=2+}}). This makes Hal one of the slowest rotators 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 and René Roy gave a much shorter period of 22.68 hours.<ref name="geneva-obs" /> The result, however, is considered of poor quality by CALL ({{small|U=1}}).<ref name="lcdb" />
=== Diameter and albedo ===
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Hal measures between 3.61 and 4.134 kilometers in diameter and its surface has an albedo between 0.26 and 0.375.<ref name="Nugent-2016" /><ref name="Masiero-2011" /><ref name="WISE" /> CALL assumes an albedo of 0.24 – derived from 8 Flora, the Flora family's parent body – and calculates a diameter of 4.11 kilometers based on an absolute magnitude of 14.1.<ref name="lcdb" />
== Naming ==
This minor planet was named after the fictional and homicidal supercomputer HAL 9000, featured in both Arthur C. Clarke's novel and Stanley Kubrick's film ''2001: A Space Odyssey'' (1968).<ref name="MPC-object" /> HAL stands for ''Heuristically programmed Algorithmic computer''. It is one of the best-known artificial intelligence characters in modern movies. The official naming citation was published by the Minor Planet Center on 4 May 1999 ({{small|M.P.C. 34628}}).<ref name="MPC-Circulars-Archive" /> The asteroid 4923 Clarke and 10221 Kubrick were named after the writer and film director, respectively.
== References == {{reflist|30em|refs=
<ref name="jpldata">{{cite web |type = 2017-05-01 last obs. |title = JPL Small-Body Database Browser: 9000 Hal (1981 JO) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009000 |publisher = Jet Propulsion Laboratory |access-date = 16 May 2018}}</ref>
<ref name="MPC-object">{{cite web |title = 9000 Hal (1981 JO) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=9000 |access-date = 16 May 2018}}</ref>
<ref name="MPC-Circulars-Archive">{{cite web |title = MPC/MPO/MPS Archive |work = Minor Planet Center |url = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html |access-date = 16 May 2018}}</ref>
<ref name="geneva-obs">{{cite web |title = Asteroids and comets rotation curves – (9000) Hal |last = Behrend |first = Raoul |publisher = Geneva Observatory |url = http://obswww.unige.ch/~behrend/page5cou.html#009000 |access-date = 16 May 2018}}</ref>
<ref name="Masiero-2011">{{cite journal |display-authors = 6 |first1 = Joseph R. |last1 = Masiero |first2 = A. K. |last2 = Mainzer |first3 = T. |last3 = Grav |first4 = J. M. |last4 = Bauer |first5 = R. M. |last5 = Cutri |first6 = J. |last6 = Dailey |first7 = P. R. M. |last7 = Eisenhardt |first8 = R. S. |last8 = McMillan |first9 = T. B. |last9 = Spahr |first10 = M. F. |last10 = Skrutskie |first11 = D. |last11 = Tholen |first12 = R. G. |last12 = Walker |first13 = E. L. |last13 = Wright |first14 = E. |last14 = DeBaun |first15 = D. |last15 = Elsbury |first16 = T. IV |last16 = Gautier |first17 = S. |last17 = Gomillion |first18 = A. |last18 = Wilkins |date = November 2011 |title = Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 20 |bibcode = 2011ApJ...741...68M |doi = 10.1088/0004-637X/741/2/68 |arxiv = 1109.4096|s2cid = 118745497 }}</ref>
<ref name="Ferret">{{cite web |title = Asteroid 9000 Hal |work = Small Bodies Data Ferret |url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=9000%20Hal |access-date = 15 May 2018}}</ref>
<ref name="lcdb">{{cite LCDB|number = 9000 |access-date = 16 May 2018}}</ref>
<ref name="Nugent-2016">{{cite journal |display-authors = 6 |first1 = C. R. |last1 = Nugent |first2 = A. |last2 = Mainzer |first3 = J. |last3 = Bauer |first4 = R. M. |last4 = Cutri |first5 = E. A. |last5 = Kramer |first6 = T. |last6 = Grav |first7 = J. |last7 = Masiero |first8 = S. |last8 = Sonnett |first9 = E. L. |last9 = Wright |date = September 2016 |title = NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos |journal = The Astronomical Journal |volume = 152 |issue = 3 |page = 12 |bibcode = 2016AJ....152...63N |doi = 10.3847/0004-6256/152/3/63 |arxiv = 1606.08923 |doi-access = free }}</ref>
<ref name="WISE">{{cite journal |display-authors = 6 |first1 = A. |last1 = Mainzer |first2 = T. |last2 = Grav |first3 = J. |last3 = Masiero |first4 = E. |last4 = Hand |first5 = J. |last5 = Bauer |first6 = D. |last6 = Tholen |first7 = R. S. |last7 = McMillan |first8 = T. |last8 = Spahr |first9 = R. M. |last9 = Cutri |first10 = E. |last10 = Wright |first11 = J. |last11 = Watkins |first12 = W. |last12 = Mo |first13 = C. |last13 = Maleszewski |date = November 2011 |title = NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 25 |bibcode = 2011ApJ...741...90M |doi = 10.1088/0004-637X/741/2/90 |arxiv = 1109.6407 |s2cid = 35447010 }} ([http://iopscience.iop.org/0004-637X/741/2/68/fulltext/apj398969t1_mrt.txt catalog])</ref>
<ref name="Galad-2009c">{{Cite journal |first1 = Adrian |last1 = Galad |first2 = Jozef |last2 = Vilagi |first3 = Leonard |last3 = Kornos |first4 = Stefan |last4 = Gajdos |date = July 2009 |title = Relative Photometry of Nine Asteroids from Modra |journal = The Minor Planet Bulletin |volume = 36 |issue = 3 |pages = 116–118 |issn = 1052-8091 |bibcode = 2009MPBu...36..116G}}</ref>
<ref name="Veres-2015">{{cite journal |display-authors = 6 |first1 = Peter |last1 = Veres |first2 = Robert |last2 = Jedicke |first3 = Alan |last3 = Fitzsimmons |first4 = Larry |last4 = Denneau |first5 = Mikael |last5 = Granvik |first6 = Bryce |last6 = Bolin |first7 = Serge |last7 = Chastel |first8 = Richard J. |last8 = Wainscoat |first9 = William S. |last9 = Burgett |first10 = Kenneth C. |last10 = Chambers |first11 = Heather |last11 = Flewelling |first12 = Nick |last12 = Kaiser |first13 = Eugen A. |last13 = Magnier |first14 = Jeff S. |last14 = Morgan |first15 = Paul A. |last15 = Price |first16 = John L. |last16 = Tonry |first17 = Christopher |last17 = Waters |date = November 2015 |title = Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results |journal = Icarus |volume = 261 |pages = 34–47 |bibcode = 2015Icar..261...34V |doi = 10.1016/j.icarus.2015.08.007 |arxiv = 1506.00762|s2cid = 53493339 }}</ref>
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== External links == * [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }}) * [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books * [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend * [https://www.minorplanetcenter.net/iau/lists/NumberedMPs005001.html Discovery Circumstances: Numbered Minor Planets (5001)-(10000)] – Minor Planet Center * {{AstDys|9000}} * {{JPL small body}}
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{{DEFAULTSORT:Hal}} 009000 Category:Discoveries by Edward L. G. Bowell Category:Named minor planets 009000 19810503