{{Short description|American astronomer (1942–1993)}} [[File:James Christy & Robert Harrington in 1978.jpg|thumb|Robert Harrington (right) with James W. Christy in 1978]] '''Robert Sutton Harrington''' (October 21, 1942 – January 23, 1993) was an American astronomer who worked at the United States Naval Observatory (USNO). Harrington was born near Newport News, Virginia. His father was an archaeologist. He was married to Betty-Jean Maycock in 1976, with two daughters, Amy and Ann.<ref name="obituary">[https://web.archive.org/web/20011112194742/http://ad.usno.navy.mil/wds/history/harrington.html Obituary]</ref>
Harrington worked at the USNO. Another astronomer there, James W. Christy, consulted with him after discovering bulges in the images of Pluto, which turned out to be Pluto's satellite Charon.<ref name=obituary/> For this reason, some consider Harrington to be a co-discoverer of Charon,<ref>{{cite web|last=Betz |first=Eric |url=http://www.astronomy.com/year-of-pluto/2015/06/an-interview-with-jim-christy-how-defective-images-revealed-the-first-double-planet |title=An interview with Jim Christy: How "defective" images revealed Pluto as a double planet |publisher=Astronomy.com |date=2015-06-09 |accessdate=2016-06-26}}</ref> although Christy usually gets sole credit. By the laws of physics, it is easy to determine the mass of a binary system based on its orbital period, so Harrington was the first to calculate the mass of the Pluto-Charon system, which was lower than even the lowest previous estimates of Pluto's mass.
For much of his career, he proposed the existence of a Planet X beyond Pluto and supported searches for it, collaborating initially with T. C. (Tom) Van Flandern.<ref name=obituary/>
Harrington died of esophageal cancer in 1993.<ref name=obituary/> The asteroid 3216 Harrington was named in his honour.
== Disproof of existence of Planet X ==
Six months before Harrington's death, E. Myles Standish had used data from ''Voyager 2'''s 1989 flyby of Neptune, which had revised the planet's total mass downward by 0.5%—an amount comparable to the mass of Mars<ref name="croswell66">Croswell (1997), p. 66.</ref>—to recalculate its gravitational effect on Uranus.<ref>{{cite journal |title= Planet X – No dynamical evidence in the optical observations |author=Myles Standish |date= 1992-07-16 |bibcode=1993AJ....105.2000S |journal=Astronomical Journal |volume= 105|pages=200–2006|issue= 5 |doi=10.1086/116575}}</ref> When Neptune's newly determined mass was used in the Jet Propulsion Laboratory Developmental Ephemeris (JPL DE), the supposed discrepancies in the Uranian orbit, and with them the need for a Planet X, vanished.<ref name="standage">{{cite book |title= The Neptune File: A Story of Astronomical Rivalry and the Pioneers of Planet Hunting |author= Tom Standage |page= [https://archive.org/details/neptunefilestory00stan/page/188 188] |isbn= 978-0-8027-1363-6 |date= 2000 |location= New York |publisher= Walker |url= https://archive.org/details/neptunefilestory00stan/page/188 }}</ref> There are no discrepancies in the trajectories of any space probes such as ''Pioneer 10'', ''Pioneer 11'', ''Voyager 1'', and ''Voyager 2'' that can be attributed to the gravitational pull of a large undiscovered object in the outer Solar System.<ref>Littmann (1990), p. 204.</ref> Although most astronomers agree that Planet X, as Lowell defined it, does not exist,<ref>{{cite book|title=The Neptune File|author=Tom Standage|publisher=Penguin|date=2000|isbn=0-8027-1363-7|page=[https://archive.org/details/neptunefilestory00stan/page/168 168]|url=https://archive.org/details/neptunefilestory00stan/page/168}}</ref> as of 2025 there is speculation concerning Planet Nine, a distinct hypothetical planet in the outer Solar System. Although the evidence and orbital properties of Planet Nine are very different from those of Harrington's Planet X, the mass estimates are similar: Planet Nine is approximately 4.4 Earth masses<ref>{{Cite journal |last1=Siraj |first1=Amir |last2=Chyba |first2=Christopher F. |last3=Tremaine |first3=Scott |date=January 2025 |title=Orbit of a Possible Planet X |journal=The Astrophysical Journal |language=en |volume=978 |issue=2 |pages=139 |doi=10.3847/1538-4357/ad98f6 |doi-access=free |arxiv=2410.18170 |bibcode=2025ApJ...978..139S |issn=0004-637X}}</ref> while Harrington's Planet X was estimated to be 4 Earth masses.<ref>{{Cite journal |last=Harrington |first=R. S. |date=October 1988 |title=The Location of Planet X |url=https://ui.adsabs.harvard.edu/abs/1988AJ.....96.1476H |journal=The Astronomical Journal |language=en |volume=96 |pages=1476 |doi=10.1086/114898 |bibcode=1988AJ.....96.1476H |issn=0004-6256}}</ref>
==See also== * Planets beyond Neptune
==References== {{reflist}}
==External links==
===Obituaries=== *[https://web.archive.org/web/20011112194742/http://ad.usno.navy.mil/wds/history/harrington.html US Naval Observatory: obituary] *[http://adsabs.harvard.edu//full/seri/BAAS./0025//0001496.000.html BAAS '''25''' (1993) 1496]
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{{DEFAULTSORT:Harrington, Robert Sutton}} Category:1942 births Category:1993 deaths Category:American astronomers