486958 Arrokoth

{{Short description|Kuiper belt object}} {{Cleanup|reason=MOS:SANDWICH in several places, incl between infobox and image|date=January 2026}} {{Use dmy dates|date=December 2019}} {{Infobox planet | minorplanet = yes | name = 486958 Arrokoth | background = #C2E0FF | image = UltimaThule CA06 color vertical.png | caption = Enhanced color image of Arrokoth captured by the ''New Horizons'' spacecraft | image_alt = Arrokoth is a lumpy, peanut-shaped body that is colored reddish-orange, as revealed in this photograph taken by the New Horizons spacecraft. | discovery_ref = <ref name="jpldata"/><ref name="MPC-object"/> | discovered = 26 June 2014 | discoverer = {{ublist | Marc W. Buie | New Horizons KBO Search }} | discovery_site = {{nowrap|Hubble Space Telescope}} | mpc_name = (486958) Arrokoth | alt_names = {{ublist | {{mp|(486958) 2014 MU|69}} | Ultima Thule (unofficial)<ref name="Ultima Thule"/> | 1110113Y | PT1 }} | pronounced = {{IPAc-en|ˈ|ær|ə|k|ɒ|θ}} | named_after = Powhatan word {{lang|pim|arrokoth}}, glossed 'sky' but probably meaning 'cloud' | mp_category = {{hlist|TNO<ref name="jpldata"/>|classical (cold)<ref name="LPSC1301"/>|distant<ref name="MPC-object"/>}} | orbit_ref = <ref name="horizons-ssb"/>{{efn|name=barycentric}} | barycentric = yes | epoch = 21 November 2025<br />(JD 2461000.5) | uncertainty = 4<ref name="jpldata"/> | observation_arc = 4.11 yr (1,500 days)<ref name="jpldata"/> | aphelion = 45.903 AU{{efn|name=barycentric}} | perihelion = 42.559 AU | semimajor = 44.231 AU{{efn|name=barycentric}} | eccentricity = 0.0378 | period = 293.97 yr{{efn|name=barycentric}} | mean_anomaly = 315.242° | mean_motion = {{Deg2DMS|0.0033528|sup=ms}} / day | inclination = 2.450° | asc_node = 159.045° | arg_peri = 183.861° | mean_diameter = {{ubl | Overall volume equivalent: {{val|19.896|u=km}}<ref name="Porter2024"/> | Wenu: {{val|17.349|u=km}}<ref name="Porter2024"/> | Weeyo: {{val|13.845|u=km}}<ref name="Porter2024"/> }} | volume = | dimensions = {{ubl | Overall best fit: {{val|34.546|x|19.838|x|13.822}} km<ref name="Porter2024"/> | {{nowrap|Wenu: {{val|20.139|x|19.838|x|13.726}} km<ref name="Porter2024"/>}} | {{nowrap|Weeyo: {{val|15.041|x|14.378|x|13.625}} km<ref name="Porter2024"/>}} }} | mass = ~{{val|7.485|e=14|u=kg}} (nominal density)<ref name="Keane2022"/> | density = {{ubl | ~{{val|0.235|u=g/cm3}} (nominal) | 1-sigma range: {{val|0.155|-|0.600|u=g/cm3}}<ref name="Keane2022"/> }} | rotation = {{val|15.9380|0.0005|ul=h}}<ref name="Buie2020"/> | surface_grav = ~{{val|0.0001|u=g}} (~{{val|0.001|u=m/s2}})<ref name="LPSC-2019-03-21"/>{{rp|28:45}} | axial_tilt = {{val|100.39|u=deg}} wrt orbit<ref name="Porter2024"/> | right_asc_north_pole = {{val|319.37|u=°}}<ref name="Porter2024"/> | declination = {{val|-25.588|u=°}}<ref name="Porter2024"/> | albedo = {{ubl | {{val|0.21|0.05|0.04}} (geometric)<ref name="Hofgartner2020"/> | {{val|0.062|0.015}} (Bond)<ref name="Hofgartner2020"/> }} | temp_name1 = (approx) | min_temp_1 = 29 K | mean_temp_1 = 42 K | max_temp_1 = 60 K | spectral_type = {{ubl | V−I {{=}} {{val|1.35}}<ref name="Benecchi2019b"/> | G−I {{=}} {{val|1.42|0.14}}<ref name="Thirouin2019"/> | G−R {{=}} {{val|0.95|0.14}}<ref name="Thirouin2019"/> }} | magnitude = 26.6<ref name="Benecchi2019b"/> | abs_magnitude = {{hlist|10.4 (V-band)<ref name="Hofgartner2020"/>|11.1<ref name="jpldata"/><ref name="MPC-object"/>}} }}

'''486958 Arrokoth''' (provisional designation '''{{mp|2014 MU|69}}'''; formerly nicknamed '''Ultima Thule'''{{efn|name=Pronunciation2|''Thule'' is classically pronounced {{IPAc-en|ˈ|θj|uː|l|iː}} {{respell|THEW|lee}}.<ref>{{cite OED |Thule |id=201483 |date=September 2022 |access-date=29 December 2020}}</ref> The ''New Horizons'' team used this pronunciation alongside the pseudo-Latin pronunciation {{IPAc-en|ˈ|t|uː|l|eɪ}} {{respell|TOO|lay}} and a hybrid pronunciation {{IPAc-en|ˈ|t|uː|l|iː}} {{respell|TOO|lee}}.<ref>{{cite web|url=http://pluto.jhuapl.edu/News-Center/Resources/Press-Kits/NewHorizonsPressKit__UT.pdf|title=New Horizons Press Kit|date=December 2018|access-date=1 January 2019|publisher=Applied Physics Laboratory|page=5}}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=Tlh2uG4yJLs | archive-url=https://ghostarchive.org/varchive/youtube/20211114/Tlh2uG4yJLs| archive-date=2021-11-14 | url-status=live|title=New Horizons: First Images of Ultima Thule |publisher=Applied Physics Laboratory |website=YouTube |date=1 January 2019}}{{cbignore}}</ref>}}) is a small, icy Kuiper belt object orbiting the Sun beyond Neptune and Pluto. It became the furthest object in the Solar System visited by a spacecraft when the NASA space probe ''New Horizons'' flew past it on 1 January 2019.<ref name="explored"/><ref name="about"/><ref name="LPSC1611"/> Arrokoth was discovered on 26 June 2014 by astronomer Marc Buie and the ''New Horizons'' Search Team, who had been using the Hubble Space Telescope to find Kuiper belt objects that ''New Horizons'' could visit.<ref name="lauer-sciam"/>

Arrokoth is a contact binary—a "snowman"-shaped object composed of two lobes connected by a narrow neck of material. The lobes of Arrokoth, named Wenu and Weeyo, are believed to be former planetesimals that once formed a binary system, but gently merged together. Wenu and Weeyo have flattened shapes consisting of distinct mounds, which indicate that they formed from a collection of smaller planetesimals 4.5 billion years ago. The surface of Arrokoth is tinted red by tholins and shows little cratering, which suggests that it has undergone little change since its formation. The primitive nature of Arrokoth is supported by its nearly circular and low-inclination orbit around the Sun, which suggests that it has never been disturbed by the gravitational influence of the planets.

== Name == When Arrokoth was first observed by the Hubble Space Telescope in 2014, it was designated {{mp|1110113Y}} in the context of the telescope's search for Kuiper belt objects,<ref name="hubble_2_KBOs" /> and was nicknamed "11" for short.<ref name="Buie" /><ref name="NASA-new-target-2015" /> Its existence as a potential target of the ''New Horizons'' probe was announced by NASA in October 2014<ref name="potential-KBOs-2014" /><ref name="Wall2014" /> and it was unofficially designated as "Potential Target 1", or {{mp|PT1}}.<ref name="NASA-new-target-2015" /> Its official provisional designation, {{mp|2014 MU|69}}, was assigned by the Minor Planet Center in March 2015, after sufficient orbital information had been gathered.<ref name="NASA-new-target-2015" /> The provisional designation indicates that Arrokoth was the 1745th minor planet to be assigned a provisional designation during the second half of June 2014.<ref name="designation"/> After further observations refining its orbit, it was given the permanent minor planet number 486958 on 12 March 2017.<ref name="MPC103886" />

=== Ultima Thule === Before the flyby on 1 January 2019, NASA invited suggestions from the public on a nickname to be used for the object.<ref name="nickname" /> One of the choices, ''Ultima Thule'',{{efn|name=Pronunciation2}} was selected on 13 March 2018.<ref name="Ultima Thule" /><ref name="Wall2018" /> {{lang|la|Thule}} ({{langx|grc|Θούλη}}, {{transliteration|grc|Thoúlē}}) is the northernmost location mentioned in ancient Greek and Roman literature and cartography, while in classical and medieval literature {{lang|la|ultima Thule}} (Latin for 'farthermost Thule') acquired a metaphorical meaning of any distant place located beyond the "borders of the known world".<ref>{{cite book|last1=Herrero|first1=Nieves|url=https://books.google.com/books?id=qu3jCQAAQBAJ&q=%22In+medieval+geography%2C+however%2C+Ultima+Thule+referred+to+any+far+away+place%22&pg=PA122|title=The Tourism Imaginary and Pilgrimages to the Edges of the World|last2=Roseman|first2=Sharon R.|publisher=Channel View Publications|year=2015|isbn=978-1-84541-523-5|page=122}}</ref><ref name="Ultima Thule" /> Once it was determined that the body was a contact binary, the ''New Horizons'' team nicknamed the larger lobe "Ultima" and the smaller lobe "Thule".<ref name="OccultationRevisited" /> They are now formally named "Wenu" and "Weeyo", respectively.<ref name="McKinnon2022"/>

Following the selection of the nickname, it was criticized by a ''Newsweek'' columnist because of the use of "Thule" by 19th-century racists as the mythical homeland of the Aryan race.<ref>{{Cite news|url=https://www.newsweek.com/nasa-named-its-next-new-horizons-target-ultima-thule-mythical-land-nazi-844318|title=NASA Named Its Next New Horizons Target Ultima Thule, a Mythical Land With a Nazi Connection|last=Bartels|first=Meghan|date=14 March 2018|publisher=Newsweek|access-date=2 April 2025}}</ref> The ''New York Times'', crediting ''Newsweek'', quoted several scientists and historians who expressed being unhappy about the name's connection to the Nazi Party.<ref name="Thule_NYTimes">{{Cite news|url=https://www.nytimes.com/2019/11/13/science/space/nasa-arrokoth-kuiper-belt.html|title=NASA Renames Object After Uproar Over Old Name's Nazi Connotations|date=13 November 2019|first=Liam|last=Stack|work=New York Times|access-date=2 April 2025}}</ref> In November 2019, the International Astronomical Union (IAU) announced the object's permanent official name, ''Arrokoth''.<ref>{{Cite web|last=Ahmed|first=Issam|date=12 November 2019|title=NASA renames faraway ice world after Nazi-link backlash (Update)|url=https://phys.org/news/2019-11-nasa-renames-faraway-ice-world.html|access-date=26 February 2021|website=Phys.org}}</ref><ref name="Thule_NYTimes"/>

=== Arrokoth === thumb|left|Pamunkey tribal elder Reverend Nick Miles commencing the naming ceremony for Arrokoth

The name ''Arrokoth'' was chosen by the ''New Horizons'' team to represent the Powhatan people indigenous to the Tidewater region of Virginia and Maryland in the eastern United States.<ref name="jhuapl-20191112"/> The Hubble Space Telescope and the Johns Hopkins University Applied Physics Laboratory, which were prominently involved in Arrokoth's discovery, were both operated from the Tidewater region of Maryland.<ref name="jhuapl-20191112"/><ref name="MPC118222"/>

With the permission of the elders of the Pamunkey Indian Tribe of the Powhatan nation, the name ''Arrokoth'' was proposed to the IAU and formally announced by the ''New Horizons'' team in a ceremony held at the NASA Headquarters in the District of Columbia on 12 November 2019.<ref name="jhuapl-20191112"/> Prior to the ceremony, the name was accepted by the IAU's Minor Planet Center on 8 November, and the ''New Horizons'' team's naming citation was published in a Minor Planet Circular on 12 November.<ref name="MPC118222" />

The Powhatan language became extinct in the late 18th century and little was recorded of it. In an old word list, {{lang|pim|arrokoth}} is glossed as 'sky', and this was the meaning intended by the New Horizons team, but it would seem that it actually meant 'cloud'.{{efn|The only record of the word was collected in 1610–1611 by English writer William Strachey, who had a decent ear but bad handwriting, and scholars since have had considerable difficulty reading his notes. The meanings of the words are also often uncertain, as Strachey and the Powhatan had no language in common. Siebert (1975: p. 324) used comparison with other Algonquian languages to interpret Strachey's handwriting, and deciphers two relevant transcriptions as {{angle bracket|arrokoth}} 'sky' and {{angle bracket|arrahgwotuwss}} 'clouds'. He reconstructs these as the word {{IPA|/aːrahkwat/}} 'cloud' and its plural {{IPA|/aːrahkwatas/}} 'clouds' (compare Ojibwa {{IPA|/aːnakkwat/}} 'cloud'), from the Proto-Algonquian {{IPA|*aːlaxkwatwi}} 'it is a cloud, it is cloudy'.<ref>{{cite book |last=Siebert |first=Frank |article=Resurrecting Virginia Algonquian from the dead: The reconstituted and historical phonology of Powhatan |editor-first=James |editor-last=Crawford |title=Studies in Southeastern Indian Languages |publisher=University of Georgia Press |year=1975 |pages=285–453 |chapter-url=https://archive.org/details/siebert-resurrecting-virginia-algonquian-from-the-dead-1975/}}</ref><ref>{{cite web|last=Hewson|first=John|title=*aᐧlaxkwatwi|url=https://protoalgonquian.atlas-ling.ca/#!/entry/5ab2bd98-d498-4825-89b4-15f4074b97b0|work=Proto-Algonquian Online Dictionary|publisher=Carleton University, School of Linguistics and Applied Language Studies|year=2017}}</ref> Given that the first vowel is long ({{IPA|/aː/}}), that syllable would have been stressed in Powhatan, so the name is approximatable in English as {{respell|ARR|o-koth}}.}} {{clear|left}}

== Shape == upright=1.25|thumb|Shape model of Arrokoth constructed from ''New Horizons'' imagery {{asof|2024|lc=y}}, viewed from the rotational south pole.<ref name="Porter2024"/> thumb|upright=1.25|Shape model of Arrokoth constructed from ''New Horizons'' imagery {{asof|2024|lc=y}}, viewed from the equator. The model's rotational north pole points up. Red areas show regions that were not well-imaged by ''New Horizons''.<ref name="Porter2024"/>

Arrokoth is a contact binary consisting of two hexagonally-shaped lobes attached by a narrow neck or waist, which is encircled by a bright band named ''Akasa Linea''.<ref name="Porter2024"/>{{rp|11}} The lobes were likely once two objects that later merged in a slow collision.<ref name="SP-20190104"/> The larger lobe, formally named Wenu Lobus, is slightly flattened and measures about {{cvt|20.1|km|mi}} across its longest axis, while the smaller lobe, Weeyo Lobus, is roughly spherical measures about {{cvt|15.0|km|mi}} across its longest axis.<ref name="Porter2024"/>{{rp|10}} Based on shape models of Arrokoth constructed from images taken by the ''New Horizons'' spacecraft, the dimensions of Wenu are approximately {{cvt|20.1|x|19.8|x|13.7|km|mi}} while the dimensions of Weeyo are approximately {{cvt|15.0|x|14.4|x|13.6|km|mi}}. Wenu's volume is nearly exactly twice that of Weeyo.<ref name="Porter2024"/>{{rp|11}} As a whole, Arrokoth is {{cvt|34.5|km|mi}} across its longest axis and is about {{cvt|13.8|km|mi}} thick.<ref name="Porter2024"/>{{rp|10}}

The longest axes of both lobes are nearly aligned with each other and to the rotational axis, which is situated between them.<ref name="eaaw9771"/> This near-parallel alignment of the lobes suggests that they were mutually locked to each other, likely due to tidal forces, before merging.<ref name="eaaw9771"/> The alignment of the lobes supports the idea that the two had individually formed from the coalescence of a cloud of icy particles.<ref name="NYT-20190318kc"/>

Prior to the ''New Horizons'' flyby of Arrokoth, stellar occultations by Arrokoth had provided evidence for its bilobate shape.<ref name="Keeter2017"/> The first detailed image of Arrokoth confirmed its double-lobed appearance and was described as a "snowman" by Alan Stern, as the lobes appeared distinctively spherical.<ref name="NYT-20190103-kc"/> In February 2019, one month after the ''New Horizons'' flyby, scientists proposed that Arrokoth was extremely flattened, based on ''New Horizons'' images of Arrokoth occulting background stars after its closest approach.<ref name="Keeter2019"/> However, a 2024 reanalysis of ''New Horizons'' imagery found that Arrokoth was not as flattened as previously thought.<ref name="Porter2024"/>

== Geology ==

=== Spectra and surface === {{Multiple image | align = right | direction = | width = | image1 = UltimaThule-ColorVariation-20190318 (cropped).png | width1 = 140 | caption1 = | image2 = UltimaThule-MVIC-color-20190318.jpg | width2 = 140 | caption2 = | image3 = UltimaThule-MVIC-20190318 (cropped).png | width3 = 140 | caption | footer = MVIC color and spectral images of Arrokoth, showing subtle color variations across its surface. The third image is the same MVIC color image superimposed on the higher resolution black and white LORRI image.{{Efn|Composite of black and while and color photographs taken respectively by the LORRI and MVIC instruments aboard ''New Horizons'' on 1 January 2019.}} }}

Measurements of Arrokoth's absorption spectrum by ''New Horizons''{{'s}} LEISA spectrometer show that Arrokoth's spectrum exhibits a strong red spectral slope extending from red to infrared wavelengths at 1.2–2.5 μm.<ref name="eaaw9771"/> Spectral measurements from LEISA revealed the presence of methanol and complex organic compounds on the surface of Arrokoth, but no evidence of water ice.<ref name="eaay3705"/><ref name="Lyra2020"/> One particular absorption band in Arrokoth's spectrum at 1.8 μm indicates that these organic compounds are sulfur-rich.<ref name="Mahjoub2021"/> Given the abundance of methanol on Arrokoth's surface, it is predicted that formaldehyde-based compounds resulting from irradiation should also be present, albeit in the form of complex macromolecules.<ref name="Lisse2020"/> Arrokoth's spectrum shares similarities with that of {{mpl-|55638|2002 VE|95}} and the centaur 5145 Pholus, which also display strong red spectral slopes along with signs of methanol present on their surfaces.<ref name="eaaw9771"/>

Preliminary observations by the Hubble Space Telescope in 2016 revealed that Arrokoth has a red coloration, similar to other Kuiper belt objects and centaurs like Pholus.<ref name="NASA-20161018"/><ref name="eaaw9771"/> Arrokoth's color is redder than that of Pluto, thus it belongs to the "ultra red" population of cold classical Kuiper belt objects.<ref name="prehistoricpuzzle"/><ref name="eaba6889"/> The red coloration of Arrokoth is caused by the presence of a mix of complex organic compounds called tholins, which are produced from the photolysis of various simple organic and volatile compounds by cosmic rays and ultraviolet solar radiation. The presence of sulfur-rich tholins on Arrokoth's surface implies that volatiles such as methane, ammonia, and hydrogen sulfide were once present on Arrokoth, but were quickly lost due to Arrokoth's small mass.<ref name="LPSC2051"/><ref name="Mahjoub2021"/> However, less volatile materials such as methanol, acetylene, ethane, and hydrogen cyanide could be retained over a longer period of time, and may likely account for the reddening and production of tholins on Arrokoth.<ref name="eaaw9771"/> The photoionization of organic compounds and volatiles on Arrokoth was also thought to produce hydrogen gas that would interact with the solar wind, though ''New Horizons''{{'s}} SWAP and PEPSSI instruments did not detect any signature of solar wind interaction around Arrokoth.<ref name="eaaw9771"/>

From color and spectral measurements of Arrokoth, the surface displays subtle color variation among its surface features.<ref name="eaay3705"/> Spectral images of Arrokoth show that the Akasa (neck) region and lineation features appear less red compared to the central region of the smaller lobe Weeyo. The larger lobe Wenu also displays redder regions, informally known as "thumbprints" by the ''New Horizons'' team. The thumbprint features are located near Wenu's limb.<ref name="LPSC-2019-03-21"/> The surface albedo or reflectivity of Arrokoth varies from 5 percent to 12 percent due to various bright features on its surface.<ref name="eaaw9771"/> Its overall geometric albedo, the quantity of reflected light in visible spectrum, is measured at 21 percent, typical for most Kuiper belt objects.<ref name="Hofgartner2020"/> The overall Bond albedo (the quantity of reflected light of any wavelength) of Arrokoth is measured at 6.3 percent.<ref name="Hofgartner2020"/>

=== Craters === The surface of Arrokoth is lightly cratered and smooth in appearance.<ref name="aay3999"/> Arrokoth's surface has few small craters (from {{cvt|1|km|mi}} in size to the limits of photographic resolution), implying a paucity of impacts throughout its history.<ref name="EPSC-DPS2019-1235"/> The occurrence of impact events in the Kuiper belt is thought to be uncommon, with a very low impact rate over the course of one billion years.<ref name="craterdensity"/> Due to the slower orbital speeds of Kuiper belt objects, the speed of objects impacting Arrokoth is expected to be low, with typical impact speeds around {{cvt|300|m/s}}.<ref name="craterdensity"/> At such slow impact speeds, large craters on Arrokoth are expected to be rare. With a low frequency of impact events along with the slow speeds of impacts, Arrokoth's surface would remain preserved since its formation. The preserved surface of Arrokoth could possibly give hints to its formation process, as well as signs of accreted material.<ref name="craterdensity"/><ref name="OccultationRevisited"/>

Numerous small pits on Arrokoth's surface were identified in high resolution images from the ''New Horizons'' spacecraft.<ref name="bestview"/><ref name="jhuapl-20190222"/> The size of these pits are measured at about {{cvt|700|m|ft}} across.<ref name="bestview"/> The exact cause of these pits is unknown; several explanations for these pits include impact events, the collapse of material, the sublimation of volatile materials, or the venting and escape of volatile gases from the interior of Arrokoth.<ref name="bestview"/><ref name="jhuapl-20190222"/>

=== Surface features === <div id="geology-image" float="right">[[File:NASA-UltimaThule-Geology-NewHorizons-20190318.jpg|thumb|upright=2|The geology of Arrokoth, with comet 67P to scale. Weeyo is depicted in cool colors (blues and greens) and Wenu in warm (yellows and reds). The labels 'bm', 'dm', 'pm', 'rm' and 'um' indicate bright, dark, patterned (mottled), rough and undifferentiated material, respectively. The eight rolling topographic units 'ma' to 'mh' may be the ancestral building blocks of Wenu.<ref name="eaaw9771"/> 'sp' are small pits/craters. Green 'lc' (large crater) is Sky, the yellow bright material at the neck is Akasa Linea, and the ring surrounding the purple unit 'mh' is Ka{{hamza}}an Arcus.]]</div>

The surfaces of each lobe of Arrokoth display regions of varying brightness along with various geological features such as troughs and hills.<ref name="eaaw9771"/><ref name="EPSC-DPS2019-50"/> These geological features are thought to have originated from the clumping of smaller planetesimals that come to form the lobes of Arrokoth.<ref name="EPSC-DPS2019-896"/> The brighter regions of Arrokoth's surface, especially its bright lineation features, are thought to have resulted from the deposition of material that have rolled down from hills on Arrokoth,<ref name="prehistoricpuzzle"/> as surface gravity on Arrokoth is sufficient for this to occur.<ref name="LPSC-2019-03-21"/>

The smaller lobe, Weeyo, bears a large depression feature named 'Sky' (previously dubbed 'Maryland' after the home state of the ''New Horizons'' team).<ref name="perspective2021"/><ref name="prehistoricpuzzle"/> Assuming Sky has a circular shape, its diameter is {{cvt|6.7|km|mi}}, with a depth of {{cvt|0.51|km|mi}}.<ref name="aay3999"/> Sky is likely an impact crater that was formed by an object {{cvt|700|m|ft|-3}} across.<ref name="Grossman20190129"/> Two notably bright streaks of similar size are present within Sky, and may be remnants of avalanches where bright material rolled into the depression.<ref name="eaaw9771"/> Four subparallel troughs are present near the terminator of Weeyo, along with two possible kilometer-sized impact craters on the rim of Sky.<ref name="EPSC-DPS2019-50"/><ref name="eaaw9771"/> The surface of Weeyo exhibits bright mottled regions separated by broad, dark regions (''dm'') which may have undergone scarp retreat, in which they were eroded due to the sublimation of volatiles, exposing lag deposits of darker material irradiated by sunlight.<ref name="EPSC-DPS2019-50"/> Another bright region (''rm''), located at the equatorial end of Weeyo, exhibits rough terrain along with several topographic features that have been identified as possible pits, craters, or mounds.<ref name="eaaw9771"/> Weeyo does not display distinct units of rolling topography near Sky, likely as a result of resurfacing caused by the impact event that created the crater.<ref name="eaaw9771"/>

As on Weeyo, troughs and pit crater chains are also present along the terminator of the larger lobe Wenu. Wenu consists of eight distinctive units or blocks of rolling topography, each similarly sized at around {{cvt|5|km|mi}}.<ref name="eaaw9771"/> The units are separated by relatively bright boundary regions.<ref name="eaaw9771"/> The similar sizes of the units suggests that each was once a small planetesimal, and that they coalesced to form Wenu.<ref name="eaaw9771"/> The planetesimals are expected to have accreted slowly by astronomical standards (at speeds of several meters per second), though they must have a very low mechanical strength in order to merge and form compact bodies at these speeds.<ref name="eaaw9771"/> The central unit ('mh') is encircled by a bright annular feature, Ka{{hamza}}an Arcus (initially dubbed "The Road to Nowhere").<ref name="jhuapl-20190222"/><ref name="LPSC-2019-03-21"/> From stereographic analysis, the central unit appears to be relatively flat compared to the surrounding units.<ref name="eaaw9771"/> Stereographic analysis of Arrokoth has also shown that one particular unit located at Wenu's limb ('md') appears to have a higher elevation and tilt than the others.<ref name="eaaw9771"/>

Akasa Linea, the neck region connecting the two lobes, has a brighter and less red appearance than the surfaces of either lobe.<ref name="Beatty20190104"/> The brightness of Akasa Linea is likely due to a composition of a more reflective material than the surfaces of the lobes. One hypothesis suggests the bright material originated in the deposition of small particles that had fallen from the lobes over time.<ref name="LPSC1742"/> Since Arrokoth's center of gravity lies between the lobes, small particles are likely to roll down the steep slopes toward the center between each lobe.<ref name="Beatty20190104"/> Another proposal suggests the bright material is produced by the deposition of ammonia ice.<ref name="necklace"/> Ammonia vapor present on the surface of Arrokoth would solidify around Akasa Linea, where gases cannot escape due to the concave shape of the neck.<ref name="necklace"/> The brightness of Akasa is thought to be maintained by high seasonal axial tilt as Arrokoth orbits around the Sun.<ref name="EPSC-DPS2019-1055"/> Over the course of its orbit, Akasa Linea is shadowed when the lobes are coplanar to the direction of the Sun, at which times the neck region receives no sunlight, cooling and trapping volatiles in the region.<ref name="EPSC-DPS2019-1055"/>

In May 2020, the IAU's Working Group for Planetary System Nomenclature (WGPSN) formally established a naming theme for all features of Arrokoth, which are to be named after words for "sky" in the languages of the world, past and present.<ref name="IAU-F2-report"/> In 2021, the first few names were approved, including Sky Crater on the small lobe, later named Weeyo Lobus.<ref name="perspective2021"/> In 2022, Kaʼan Arcus was approved for the circular arc on Wenu Lobus.<ref name=SciNews-20220216>{{cite news |url= http://www.sci-news.com/space/arrokoth-features-10555.html |title= Arrokoth's Prominent Features Given Official Names |publisher= Sci-News |date= 16 February 2022 }}</ref> On 17 December 2025, Akasa Linea was changed to Akasa Collum.<ref name=":0">{{Cite web |title=Planetary Names |url=https://planetarynames.wr.usgs.gov/Feature/16442 |access-date=2025-12-19 |website=planetarynames.wr.usgs.gov}}</ref>

{| class="wikitable" |+Named features |- ! width=100 | Name !! Feature !! Named after !! Name approved<br />{{small|(Date{{·}}Ref)}} |- | Wenu Lobus || the larger lobe of Arrokoth, provisionally "Ultima" || {{lang|arn|wenu}}', the Mapudungun word for 'sky, above' || 11 April 2022<ref>{{gpn|16175|Wenu Lobus}}</ref><ref name="McKinnon2022"/> |- | Weeyo Lobus || the smaller lobe, provisionally "Thule" || {{lang|fuc|𞤱𞤫𞥅𞤴𞤮}} {{lang|fuc-Latn|weeyo}}, the Pulaar word for 'sky' || 11 April 2022<ref>{{gpn|16174|Weeyo Lobus}}</ref><ref name="McKinnon2022"/> |- | Akasa Collum || the bright ring on the neck between the lobes || আকাশ ''akaś'', the Bengali word for 'sky' || 2 September 2021, 17 December 2025<ref name=":0" /><ref>{{gpn|16220|Akasa Linea}}</ref><ref name="Keane2022"/> |- | Ka{{hamza}}an Arcus || the circular linea (the "Road to Nowhere") in the center of Wenu || ''ka{{hamza}}an'', the Mayan word for 'sky'; near homonym for 'snake'<ref name=SciNews-20220216/> || 2 September 2021<ref>{{gpn|16219|Ka{{hamza}}an Arcus}}</ref><ref name="Keane2022"/> |- | Sky || the large compaction crater on Weeyo || The English word 'sky' || 2 September 2021<ref>{{gpn|16221|Sky}}</ref><ref name="Keane2022"/> |}

=== Internal structure === Topography variations at the limb of Arrokoth suggest that its interior is likely composed of mechanically strong material consisting of mostly amorphous water ice and rocky material.<ref name="LPSC1742"/><ref name="Prentice2019"/> Trace amounts of methane and other volatile gases in the form of vapors may also be present in Arrokoth's interior, trapped in water ice.<ref name="Prentice2019"/> Under the assumption that Arrokoth has a low comet-like density of around {{val|0.5|u=g/cm3}}, its internal structure is expected to be porous, as volatile gases trapped in Arrokoth's interior are thought to escape from the interior to the surface.<ref name="eaaw9771"/><ref name="Prentice2019"/> Assuming that Arrokoth may have an internal heat source caused by the radioactive decay of radionuclides, the trapped volatile gases inside Arrokoth would migrate outward and escape from the surface, similarly to the scenario of outgassing of comets.<ref name="Prentice2019"/> The escaped gases may subsequently freeze and deposit on Arrokoth's surface, and could possibly account for the presence of ices and tholins on its surface.<ref name="Prentice2019"/><ref name="LPSC2051"/>

== Orbit and classification == {{Multiple image | align = right | direction = | width = | image1 = New Horizons potential targets 1-3.png | width1 = 230 | caption1 = The orbits of ''New Horizons'' potential targets 1 to 3. Arrokoth (PT1) is in blue, {{mpl|2014 OS|393}} (PT2) is in red, and {{mpl|2014 PN|70}} (PT3) is in green. | image2 = Animation of New Horizons trajectory.gif | width2 = 290 | caption2 = Animation of ''New Horizons''{{'s}} trajectory from 19 January 2006 to 30 December 2030<br /> {{legend2|magenta| ''New Horizons'' }}{{·}}{{legend2|lime|486958 Arrokoth}}{{·}}{{legend2|Royalblue|Earth}}{{·}}{{legend2|Gold|132524 APL}}{{·}}{{legend2|OrangeRed|Jupiter }}{{·}}{{legend2|Cyan|Pluto }} }}

Arrokoth orbits the Sun at an average distance of {{convert|44.2|AU|e9km e9mi|lk=in}}, taking 294 years to complete a full orbit around the Sun.{{efn|name=barycentric|These orbital elements are expressed in terms of the Solar System Barycenter (SSB) as the frame of reference.<ref name="horizons-ssb"/> Due to planetary perturbations, the Sun revolves around the SSB at non-negligible distances, so heliocentric-frame orbital elements and distances (such as those given in JPL's Small-Body Database<ref name="jpldata"/>) can vary on short timescales.<ref name="horizons-heliocentric"/>}} Having a low orbital eccentricity of 0.04, Arrokoth follows a nearly circular orbit around the Sun, only slightly varying in distance from 42.6 AU at perihelion to 45.9 AU at aphelion.{{efn|name=barycentric}} Because Arrokoth has a low orbital eccentricity, it does not approach close enough to Neptune for its orbit to become perturbed. (Arrokoth's minimum orbital intersection distance from Neptune is 12.7 AU.)<ref name="MPC-object"/> Arrokoth's orbit appears to be stable over long time scales; simulations by the Deep Ecliptic Survey show that its orbit will not significantly change over the next 10 million years.<ref name="Buie-DES"/> At the time of the ''New Horizons'' flyby in January 2019, Arrokoth's distance from the Sun was {{cvt|43.28|AU|e9km e9mi|sigfig=3}}.<ref name="MP-Ephemeris"/> At this distance, light from the Sun takes over six hours to reach Arrokoth.<ref name="Davis2018"/><ref name="TheSkyLive"/>

Arrokoth is generally classified as a distant minor planet or trans-Neptunian object by the Minor Planet Center as it orbits in the outer Solar System beyond Neptune.<ref name="MPC-object"/><ref name="jpldata"/> Having a non-resonant orbit within the Kuiper belt region 39.5–48 AU from the Sun, Arrokoth is classified as a classical Kuiper belt object, or cubewano.<ref name="Delsanti2006"/><ref name="LPSC1301"/> Arrokoth's orbit is inclined to the ecliptic plane by 2.45 degrees, relatively low compared to other classical Kuiper belt objects such as {{dp|Makemake}}.<ref name="MPC-TNO-list"/> Since Arrokoth has a low orbital inclination and eccentricity, it is part of the dynamically cold population of classical Kuiper belt objects, which are unlikely to have undergone significant perturbations by Neptune during its outward migration in the past. The cold classical population of Kuiper belt objects are thought to be remnant planetesimals left over from the accretion of material during the formation of the Solar System.<ref name="Delsanti2006"/><ref name="Lakdawalla2014b"/>

== Rotation and temperature == {{Multiple image | align = right | direction = | width = | image1 = Ultima Thule Rotation.gif | width1 = 175 | caption1 = Sequence of three images showing Arrokoth's rotation over a period of 2.5 hours | image2 = Rotation of Ultima Thule.gif | width2 = 175 | caption2 = Near-polar view of Arrokoth's rotation over a period of nine hours }}

Results from photometric Hubble Space Telescope observations show that the brightness of Arrokoth varies by around 0.3 magnitudes as it rotates.<ref name="Benecchi2019a"/><ref name="NH-2017"/> Though the rotation period and light curve amplitude of Arrokoth could not be determined from Hubble observations, the subtle brightness variations suggested that Arrokoth's rotational axis is either pointed toward the Earth or is being viewed at an equator-on configuration with a nearly spherical shape, with a constrained ''a''/''b'' best-fit aspect ratio around 1.0–1.15.<ref name="NH-2017"/><ref name="Benecchi2019a"/>

Upon the ''New Horizons'' spacecraft's approach to Arrokoth, no rotational light curve amplitude was detected by the spacecraft despite Arrokoth's irregular shape.<ref name="FirstMystery"/> To explain the lack of its rotational light curve, scientists surmised that Arrokoth is rotating on its side, with its rotational axis pointing nearly directly at the approaching ''New Horizons'' spacecraft.<ref name="FirstMystery"/> Subsequent images of Arrokoth from ''New Horizons'' upon approach confirmed that its rotation is tilted, with its south pole facing towards the Sun.<ref name="explored"/><ref name="LPSC1611"/> The rotational axis of Arrokoth is tilted 99 degrees to its orbit.<ref name="EPSC-DPS2019-311"/> Based on occultation and ''New Horizons'' imaging data, Arrokoth's rotation period is determined to be 15.938 hours.<ref name="Buie2020"/>

Due to the high axial tilt of its rotation, the solar irradiance of the northern and southern hemispheres of Arrokoth varies greatly over the course of its orbit around the Sun.<ref name="eaaw9771"/> As it orbits around the Sun, one polar region of Arrokoth faces the Sun continuously while the other faces away. The solar irradiance of Arrokoth varies by 17 percent due to the low eccentricity of its orbit.<ref name="eaaw9771"/> The average temperature of Arrokoth is estimated to be around {{cvt|42|K|C F}}, with a maximum of around {{val|60|u=K}} on the illuminated subsolar point of Arrokoth.<ref name="NASA-SSE"/><ref name="eaay3705"/> Radiometric measurements from the ''New Horizons'' REX instrument indicate that the mean surface temperature of Arrokoth's unilluminated face is about {{val|29|5|u=K}},<ref name="eaay3705"/> higher than the modeled range of {{val|12|-|14|u=K}}. The higher temperature of Arrokoth's unilluminated face as measured by REX implies that thermal radiation is emitted from Arrokoth's subsurface, which was predicted to be intrinsically warmer than the exterior surface.<ref name="eaay3705"/>

== Mass and density == The mass and density of Arrokoth are unknown. A definitive mass and density estimate cannot be given as the lobes are in contact rather than orbiting each other.<ref name="Beatty20190319"/> Although a possible natural satellite orbiting Arrokoth could help determine its mass,<ref name="Beatty20190104"/> no such satellites were found.<ref name="Beatty20190319"/> Under the assumption that both lobes are bound by self-gravity, with the mutual gravity of the two overcoming centrifugal forces that would otherwise separate them, Arrokoth is estimated to have a very low density similar to that of comets, with an estimated minimum density of {{val|0.29|u=g/cm3}}. In order to maintain the shape of the neck, the density of Arrokoth must be less than the maximum possible density of {{val|1|u=g/cm3}}, otherwise the neck would be excessively compressed by the mutual gravity of the lobes such that the entire object would gravitationally collapse into a spheroid.<ref name="eaaw9771"/><ref name="EPSC-DPS2019-1387"/>

== Formation == upright=2|right|thumb|{{center|Illustration depicting the hypothesized formation sequence of Arrokoth.}}

Arrokoth is thought to have formed from two separate progenitor objects that formed over time from a rotating cloud of small, icy bodies since the formation of the Solar System 4.6 billion years ago.<ref name="SP-20190104"/><ref name="prehistoricpuzzle"/> Arrokoth had likely formed in a colder environment within a dense, opaque region of the early Kuiper belt where the Sun appeared heavily obscured by dust.<ref name="Lisse2020"/> Icy particles within the early Kuiper belt experienced streaming instability, in which they slowed down due to drag against the surrounding gas and dust, and gravitationally coalesced into clumps of larger particles.<ref name="Beatty20190319"/>

Because there have been few to no disruptive impacts on Arrokoth since it formed, the details of its formation have been preserved. From the differing present appearances of the lobes, each is thought to have accreted separately while in orbit around each other.<ref name="prehistoricpuzzle"/><ref name="SPC-20190318"/> Both progenitor objects are believed to have formed from a single source of material as they appear to be homogeneous in albedo, color, and composition.<ref name="eaaw9771"/> The presence of rolling topography units on the larger object indicates that it had likely formed from the coalescence of smaller planetesimal units prior to merging with the smaller object.<ref name="SPC-20190318"/><ref name="eaaw9771"/> The larger lobe Wenu appears to be an aggregate of 8 or so smaller components, each approximately {{cvt|5|km|mi|0}} across.{{fact|date=May 2026}}

=== Flattening and merging === {{update section|date=December 2025|Arrokoth is not as flattened as previously thought--see updated information and new shape model from [https://pdssbn.astro.umd.edu/holdings/pds4-nh_derived-v3.0/arrokoth_shapemodel_porter2024/porteretal2024b.pdf Porter et al. (2024), "The Shape of (486958) Arrokoth"]}} It is unclear how Arrokoth has attained its present flattened shape, though two leading hypotheses have been postulated to explain the mechanisms leading to its flattened shape during the formation of the Solar System.<ref name="AGU-P33I-3536"/><ref name="Zhao2020"/> The ''New Horizons'' team hypothesizes that the two progenitor objects formed with initially rapid rotations, causing their shapes to become flattened due to centrifugal forces. Over time, the rotation rates of the progenitor objects gradually slowed down as they experienced impacts by small objects and transferred their angular momentum to other orbiting debris left over from their formation.<ref name="AGU-P33I-3536"/> Eventually, loss of momentum, caused by impacts and momentum shifting to other bodies in the cloud, caused the pair to slowly spiral closer until they touched—where over time the joints fused together, forming its present bilobate shape.<ref name="SP-20190104"/><ref name="AGU-P33I-3536"/>

In an alternative hypothesis formulated by researchers of the Chinese Academy of Sciences and the Max Planck Institute in 2020, the flattening of Arrokoth may have resulted from the process of sublimation-driven mass loss over a timescale of several million years after the merging of the lobes. At the time of formation, Arrokoth's composition had a higher volatile concentration from the accretion of condensed volatiles within the dense and opaque Kuiper belt. After the surrounding dust and nebula subsided, solar radiation was no longer obstructed, allowing for photon-induced sublimation to occur in the Kuiper belt. Due to Arrokoth's high rotational obliquity, one polar region faces the Sun continuously for half of its orbital period, resulting in extensive heating and consequent sublimation and loss of frozen volatiles at Arrokoth's poles.<ref name="Zhao2020"/>

Regardless of the uncertainty surrounding the mechanisms for the flattening of Arrokoth, the subsequent merging of the bodies ancestral to the lobes appeared to be gentle. The present appearance of Arrokoth does not indicate deformation or compression fractures, suggesting that the two progenitor objects had merged very slowly at a speed of {{cvt|2|m/s|ft/s}}—comparable to the average walking speed of a person.<ref name="eaaw9771"/><ref name="SPC-20190318"/> The progenitor objects must have also merged obliquely at angles greater than 75 degrees in order to account for the present shape of Arrokoth's thin neck while keeping the lobes intact. By the time the two progenitor objects merged, both of them had already been tidally locked in synchronous rotation.<ref name="Marohnic2020"/>

The long-term frequency of impact events occurring on Arrokoth was low due to the slower speeds of objects in the Kuiper belt.<ref name="craterdensity"/> Over a period of 4.5 billion years, photon-induced sputtering of water ice on Arrokoth's surface would minimally reduce its size by {{cvt|1|cm|in}}.<ref name="eaaw9771"/> With the lack of frequent cratering events and perturbations of its orbit, the shape and appearance of Arrokoth would remain virtually pristine since the conjoining of two separate objects that formed its bilobate shape.<ref name="craterdensity"/><ref name="about"/>

== Observation ==

=== Discovery === {{See also|New Horizons#Kuiper belt object mission}} [[File:2014 MU69 Discovery Images Animated.gif|thumb|Discovery images of Arrokoth, cropped from five Wide Field Camera 3 images taken by the Hubble Space Telescope on 26 June 2014.]]

Arrokoth was discovered on 26 June 2014 using the Hubble Space Telescope during a preliminary survey to find a suitable Kuiper belt object for the ''New Horizons'' spacecraft to fly by. Scientists of the ''New Horizons'' team were searching for an object in the Kuiper belt that the spacecraft could study after Pluto, and their next target had to be reachable on ''New Horizons''{{'s}} remaining fuel.<ref name="Lakdawalla2014a"/><ref name="Lakdawalla2014b"/> Using large ground-based telescopes on Earth, researchers began looking in 2011 for candidate objects and searched multiple times per year for several years.<ref name="Witze2014"/> However, none of the objects found were reachable by the ''New Horizons'' spacecraft and most Kuiper belt objects that may be suitable were just too distant and faint to be seen through Earth's atmosphere.<ref name="Lakdawalla2014a"/><ref name="Witze2014"/> In order to find these fainter Kuiper belt objects, the ''New Horizons'' team initiated a search for suitable targets with the Hubble Space Telescope on 16 June 2014.<ref name="Lakdawalla2014a"/>

Arrokoth was first imaged by Hubble on 26 June 2014, 10 days after the ''New Horizons'' team began their search for potential targets.<ref name="Lakdawalla2014b"/> While digitally processing images from Hubble, Arrokoth was identified by astronomer Marc Buie, member of the ''New Horizons'' team.<ref name="lauer-sciam"/><ref name="Lakdawalla2014b"/> Buie reported his finding to the search team for subsequent analysis and confirmation.<ref name="Parker2016"/> Arrokoth was the second object found during the search, after {{mpl|2014 MT|69}}.<ref name="EPSC2015"/> Three more candidate targets were later discovered with Hubble, though follow-up astrometric observations eventually ruled them out.<ref name="EPSC2015"/><ref name="NASA-new-target-2015"/> Of the five potential targets found with Hubble, Arrokoth was deemed to be the most feasible target for the spacecraft as the flyby trajectory required the least amount of fuel compared to that for {{mpl|2014 PN|70}}, the second most feasible target for ''New Horizons''.<ref name="LPSC1301"/><ref name="Stern-Extended"/> On 28 August 2015, Arrokoth was officially selected by NASA as a flyby target for the ''New Horizons'' spacecraft.<ref name="NASA-new-target-2015"/>

Arrokoth is too small and distant for its shape to be observed directly from Earth, but scientists were able to take advantage of an astronomical event called a stellar occultation, in which the object passes in front of a star from the vantage point of Earth. Since the occultation event is only visible from certain parts of the Earth, the ''New Horizons'' team combined data from Hubble and the European Space Agency's ''Gaia'' space observatory to figure out exactly when and where on Earth's surface Arrokoth would cast a shadow.<ref name="MU69occ rationale"/><ref name="Planetaria"/> They determined that occultations would occur on 3 June, 10 July, and 17 July in 2017, and set off for places around the world where they could see Arrokoth cover up a different star on each of these dates.<ref name="MU69occ rationale"/> Based on this string of three occultations, scientists were able to trace out the object's shape.<ref name="MU69occ rationale"/>

=== 2017 occultations === {{Multiple image | header = Results of the 2017 occultation campaign | align = right | image1 = Wink-of-a-star-2.gif | width1 = 165 | image2 = 20170808-MU69Chart.jpg | width2 = 139 | image3 = MU69 occultation fit cropped.png | width3 = 186 | footer = Arrokoth briefly blocked the light from an unnamed star in Sagittarius during an occultation on 17 July 2017. Data from 24 telescopes that captured this event revealed Arrokoth's possible bilobate or binary shape. After the flyby in January 2019, the results from the occultation were shown to precisely fit the observed size and shape of the object.<ref name="OccultationRevisited"/>}} {{Multiple image | total_width = 400 | align = right | header = Pre-flyby conceptual art, based on occultation data | image1 = PIA21867-2014MU69-BinaryObject-ArtConcept-20170804.jpg | caption1 = Artist concept of Arrokoth as a contact binary, illustrating the understanding as of August 2017 | image2 = PIA21868-2014MU69-SingleObject-ArtConcept-20170804.jpg | caption2 = Artist concept of an ellipsoid shape for Arrokoth, a shape that could not be ruled out prior to the flyby in 2019}} In June and July 2017, Arrokoth occulted three background stars.<ref name="MU69occ rationale"/> The team behind ''New Horizons'' formed a specialized "KBO Chasers" team led by Marc Buie to observe these stellar occultations from South America, Africa, and the Pacific Ocean.<ref name="MU69occ"/><ref name="KBO chasers"/><ref name="jhuapl-20170719"/> On 3 June 2017, two teams of NASA scientists tried to detect the shadow of Arrokoth from Argentina and South Africa.<ref name="FirstOccultation"/> When they found that none of their telescopes had observed the object's shadow, it was initially speculated that Arrokoth might be neither as large nor as dark as previously expected, and that it might be highly reflective or even a swarm.<ref name="FirstOccultation"/><ref name="TheOuterSanctum"/> Additional data taken with the Hubble Space Telescope in June and July 2017 revealed that the telescopes had been placed in the wrong location, and that these estimations were incorrect.<ref name="TheOuterSanctum"/>

On 10 July 2017, the airborne telescope SOFIA was successfully placed close to the predicted centerline for the second occultation while flying over the Pacific Ocean from Christchurch, New Zealand. The main purpose of those observations was the search for hazardous material like rings or dust near Arrokoth that could threaten the ''New Horizons'' spacecraft during its flyby in 2019. Data collection was successful. A preliminary analysis suggested that the central shadow was missed;<ref name="NYT-2017"/> only in January 2018 was it realized that SOFIA had indeed observed a very brief dip from the central shadow.<ref name="Science Team Meeting"/> The data collected by SOFIA will also be valuable to put constraints on dust near Arrokoth.<ref name="SOFIA 1"/><ref name="SOFIA 2"/> Detailed results of the search for hazardous material were presented on the 49th Meeting of the AAS Division for Planetary Sciences, on 20 October 2017.<ref name="DPS49-7"/>

On 17 July 2017, the Hubble Space Telescope was used to check for debris around Arrokoth, setting constraints on rings and debris within the Hill sphere of Arrokoth at distances of up to {{cvt|75000|km|mi}} from the main body.<ref name="Kammer2018"/> For the third and final occultation, team members set up another ground-based "fence line" of 24 mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina (Chubut and Santa Cruz provinces) to better constrain the size of Arrokoth.<ref name="KBO chasers"/><ref name="jhuapl-20170719"/> The average spacing between these telescopes was around {{cvt|4|km|mi}}.<ref name="LPSC3120"/> Using the latest observations from Hubble, the position of Arrokoth was known with much better precision than for the 3 June occultation, and this time the shadow of Arrokoth was successfully observed by at least five of the mobile telescopes.<ref name="jhuapl-20170719"/> Combined with the SOFIA observations, this put constraints on possible debris near Arrokoth.<ref name="SOFIA 2"/>

Results from the occultation on 17 July showed that Arrokoth could have had a very oblong, irregular shape or be a close or contact binary.<ref name="LPSC3120"/><ref name="Keeter2017"/> According to the duration of the observed chords, Arrokoth was shown to have two "lobes", with diameters of approximately {{cvt|20|km|mi}} and {{cvt|18|km|mi}}, respectively.<ref name="NH-2017"/> A preliminary analysis of all collected data suggested that Arrokoth was accompanied by an orbiting moonlet about {{cvt|200|–|300|km|mi}} away from the primary.<ref name="2017 AGU"/> It was later realized, however, that an error with the data processing software resulted in a shift in the apparent location of the target. After accounting for the bug, the short dip observed on 10 July was considered to be a detection of the primary body.<ref name="Science Team Meeting"/>

By combining data about its light curve,<ref name="Benecchi2019a"/> spectra (e.g. color), and stellar occultation data,<ref name="LPSC3120"/> illustrations could rely on known data to create a concept of what it might look like prior to spacecraft flyby.

=== 2018 occultations === [[File:MU69 occultation 2018August4.png|thumb|Path of Arrokoth's shadow on Earth during its 4 August 2018 occultation of an unnamed star in Sagittarius. This event was successfully observed from locations in Senegal and Colombia.]]

There were two potentially useful Arrokoth occultations predicted for 2018: one on 16 July and one on 4 August. Neither of these were as good as the three 2017 events.<ref name="MU69occ rationale"/> No attempts were made to observe the 16 July 2018 occultation, which took place over the South Atlantic and the Indian Ocean. For the 4 August 2018 event, two teams, consisting of about 50 researchers in total, went to locations in Senegal and Colombia.<ref name="August4preparation"/> The event gathered media attention in Senegal, where it was used as an opportunity for science outreach.<ref name="AFIPS"/> Despite some stations being affected by bad weather, the event was successfully observed, as reported by the ''New Horizons'' team.<ref name="success"/> Initially, it was unclear whether a chord on the target had been recorded. On 6 September 2018, NASA confirmed that the star had indeed been seen to dip by at least one observer, providing important information about the size and shape of Arrokoth.<ref name="Keeter2018"/>

Hubble observations were carried out on 4 August 2018, to support the occultation campaign.<ref name="hst15450"/><ref name="August4preparation"/> Hubble could not be placed in the narrow path of the occultation, but due to the favourable location of Hubble at the time of the event, the space telescope was able to probe the region down to {{cvt|1600|km|mi}} from Arrokoth. This is much closer than the {{cvt|20000|km|mi}} region that could be observed during the 17 July 2017 occultation. No brightness changes of the target star have been seen by Hubble, ruling out any optically thick rings or debris down to {{cvt|1600|km|mi}} from Arrokoth.<ref name="Keeter2018"/> Results of the 2017 and 2018 occultation campaigns were presented at the 50th meeting of the American Astronomical Society Division for Planetary Sciences on 26 October 2018.<ref name="preencounter"/>

== Exploration == {{See also|New Horizons#Encounter with Arrokoth}} [[File:Ultima Thule approach video1.gif|left|thumb|upright|Arrokoth among the stars of Sagittarius—with and without background star omission {{small|(apparent magnitude 20 to 15; late 2018)}}.<ref name="JPLHorizonsX"/>]] thumb|Movie of ''New Horizons''{{'s}} approach to Arrokoth, constructed from images taken by the spacecraft during its flyby on 1 January 2019<ref name="prehistoricpuzzle"/> left|thumb|upright|View of Arrokoth by ''New Horizons'' after closest approach. The silhouette of Arrokoth's shape can be seen among the background stars.

Having completed its flyby of Pluto in July 2015, the ''New Horizons'' spacecraft made four course changes in October and November 2015 to place itself on a trajectory towards Arrokoth.<ref name="jhuapl-20151105"/> It is the first object to be targeted for a flyby that was discovered after the visiting spacecraft was launched,<ref name="Lakdawalla2015"/><ref>{{cite news |title=The Journey Continued – Exactly Five Years Ago, the New Horizons Team Discovered 2014 MU69 – and Prepared to Make the Distant Kuiper Belt Object Part of Space Exploration History |url=http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190626 |publisher=Applied Physics Laboratory |website=pluto.jhuapl.edu |date=26 June 2019}}</ref> and is the farthest object in the Solar System ever to be visited by a spacecraft.<ref name="NASA-new-target-2015"/><ref name="NYT-20181231"/><ref name="NYT-20181230"/> Moving at a speed of {{cvt|51500|kph|km/min km/s mph|abbr=on}}<ref>{{cite magazine |url=https://www.skyandtelescope.com/astronomy-news/new-horizons-approaching-ultima-thule/ |title=New Horizons: Ultima Thule is dead ahead |first=Allan |last=Stern |magazine=Sky and Telescope |date=26 December 2018}}</ref> ''New Horizons'' passed by Arrokoth at a distance of {{cvt|3538|km|mi}}, equivalent to a few minutes of travel at the craft's speed, and one third of the distance of the spacecraft's closest encounter with Pluto.<ref name="aay3999"/> Closest approach occurred on 1 January 2019, at 05:33 UTC (Spacecraft Event Time – SCET)<ref name="2017 AGU"/><ref name="WhatToExpect"/> at which point it was {{val|43.4|ul=AU}} from the Sun in the direction of the constellation Sagittarius.<ref name="jhuapl-20151023"/><ref name="jhuapl-20151026b"/><ref name="jhuapl20151029"/><ref name="TheSkyLive"/> At this distance, the one-way transit time for radio signals between Earth and ''New Horizons'' was 6 hours.<ref name="2017 AGU"/>

''New Horizons'' closest approach was towards the celestial north of Arrokoth.<ref name="eaaw9771" /> Owing to Arrokoth's tilted rotation (with its rotational axis south pole facing towards the Sun<ref name="explored" /><ref name="LPSC1611" />), the rotational north pole hemisphere was mostly in darkness during ''New Horizons'' flyby''.<ref name="eaaw9771" />''

The science objectives of the flyby include characterizing the geology and morphology of Arrokoth, and mapping the surface composition (searching for ammonia, carbon monoxide, methane, and water ice). Surveys of the surrounding environment to detect possible orbiting moonlets, a coma, or rings, were conducted.<ref name="2017 AGU" /> Images with resolutions showing details of {{cvt|30|m|ft}} to {{cvt|70|m|ft}} are expected.<ref name="2017 AGU" /><ref name="jhuapl-20170906" /> From Hubble observations, faint, small satellites orbiting Arrokoth at distances greater than {{cvt|2000|km|mi}} have been excluded to a depth of >29th magnitude.<ref name="Benecchi2019a" /> The object has no detectable atmosphere, and no large rings or satellites larger than {{cvt|1.6|km|mi|0}} in diameter.<ref name="SN-20190104" /> Nonetheless, a search for a related moon (or moons) continues, which may help better explain the formation of Arrokoth from two individual orbiting objects.<ref name="SP-20190104" />

''New Horizons'' made its first detection of Arrokoth on 16 August 2018, from a distance of {{convert|107|e6mi|e6km|abbr=unit|order=flip}}.<ref name="jhuapl-20180828"/> At that time, Arrokoth was visible at magnitude 20, in the direction of the constellation Sagittarius.<ref name="jhuapl-20181218"/> Arrokoth was expected to be magnitude 18 by mid-November, and magnitude 15 by mid-December. It reached naked eye brightness (magnitude 6) from the spacecraft's point of view just 3–4 hours before closest approach.<ref name="JPLHorizonsX"/> If obstacles were detected, the spacecraft had the option of diverting to a more distant rendezvous, though no moons, rings or other hazards were seen.<ref name="2017 AGU"/><ref name="jhuapl-20181218"/> High-resolution images from ''New Horizons'' were taken on 1 January. The first images of mediocre resolution arrived the next day.<ref name="NYT-20190102-kc"/> The downlink of data collected from the flyby was expected to last 20 months, through September 2020.<ref name="WhatToExpect"/> {{clear}}

== Gallery == {{Multiple image | header = LORRI images of Arrokoth from December 2018 to January 2019<ref name="LORRI-images"/> | align = center | total_width = 1210 | image1 = Newhorizonschristmasthule.png | caption1 = 24 Dec 2018, at a distance of {{convert|10|e6km|e6mi|abbr=unit}} | image2 = Ultima Thule Comes into Focus (Processed).png | caption2 = 24 hours before closest approach, {{convert|1.9|e6km|e6mi|abbr=unit}} | image3 = Detecting Ultima Thule's Size and Shape on Approach (cropped).png | caption3 = 12 hours before closest approach, {{convert|1|e6km|e6mi|abbr=unit}} | image4 = First color image of Ultima Thule (LORRI crop).png | caption4 = 4:08 UT (SCET), {{cvt|137000|km|mi}} | image5 = NH-UltimaThule-20190102 crop.png | caption5 = 5:01 UT, {{cvt|73900|km|mi}} | image6 = Ultima Thule Near Closest Approach CA05.png | caption6 = 5:14 UT, {{cvt|16700|km|mi}} | image7 = Ultima Thule New Horizons CA06 vertical.png | caption7 = 5:27 UT, {{nowrap|{{cvt|6600|km|mi}}{{efn|Taken 6.5 minutes before closest approach at 5:33 UT. Note that the view and illumination is now from a slightly different angle as the spacecraft begins to bypass Arrokoth.}}}} | image8 = Arrokoth Crescent Sharpened (rotated).png | caption8 = 5:42 UT, after closest approach; {{cvt|8900|km|mi}} }}

== See also == {{Portal|Solar System}} * List of minor planets and comets visited by spacecraft * 132524 APL – Another minor planet visited by ''New Horizons'' * List of trans-Neptunian objects

==Notes== {{notelist|25em}}

==References== {{reflist|25em|refs=

<ref name="jpldata">{{cite web |type = 2018-08-04 last obs. |title = JPL Small-Body Database Lookup: 486958 Arrokoth (2014 MU69) |url = https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=486958 |publisher = Jet Propulsion Laboratory |access-date = 2025-12-05}}</ref>

<ref name="horizons-ssb">{{cite web |title = JPL Horizons On-Line Ephemeris for 486958 Arrokoth (2014 MU69) at epoch JD 2461000.5 (2025-Nov-21) |url = https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND='Arrokoth'&TABLE_TYPE='ELEMENTS'&START_TIME='JD2461000.5'&STOP_TIME='JD2461200.5'&STEP_SIZE='1y'&CENTER='@0'&OUT_UNITS='AU-D' |work = JPL Horizons On-Line Ephemeris System |publisher = Jet Propulsion Laboratory |accessdate = 2025-12-05}} Solution using the Solar System Barycenter. Ephemeris Type: Elements and Center: @0)</ref>

<ref name="horizons-heliocentric">{{cite web |title = JPL Horizons On-Line Ephemeris for 486958 Arrokoth (2014 MU69) at epochs JD 2450000.5–2460000.5 |url = https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND='Arrokoth'&TABLE_TYPE='ELEMENTS'&START_TIME='JD2450000.5'&STOP_TIME='JD2470000.5'&STEP_SIZE='200d'&CENTER='500@10'&OUT_UNITS='AU-D' |work = JPL Horizons On-Line Ephemeris System |publisher = Jet Propulsion Laboratory |accessdate = 2025-12-08}} Solution using the Sun. Ephemeris Type: Elements and Center: @sun)</ref>

<ref name="MPC-object">{{cite web |title = (486958) Arrokoth = 2014 MU69 |url = http://www.minorplanetcenter.net/db_search/show_object?object_id=486958 |publisher = Minor Planet Center |access-date = 2025-12-05}}</ref>

<ref name="MP-Ephemeris">{{cite web |title = Minor Planet Ephemeris Service: Query Results |type = Settings: "Return ephemerides", Ephemeris Options: start date "2018/12/31" and output dates "365" |url = https://minorplanetcenter.net//iau/MPEph/MPEph.html |work = Minor Planet & Comet Ephemeris Service |publisher = Minor Planet Center |access-date = 4 February 2020}}</ref>

<ref name="MPC-TNO-list">{{cite web |title = List Of Trans-Neptunian Objects |url = http://www.minorplanetcenter.net/iau/lists/t_tnos.html |work = Minor Planet Center |publisher = International Astronomical Union |access-date = 4 February 2020}}</ref>

<ref name="Buie-DES">{{cite web |title = Orbit Fit and Astrometric record for 486958 |url = http://www.boulder.swri.edu/~buie/kbo/astrom/486958.html |last = Buie |first = Marc W. |author-link = Marc W. Buie |publisher = Southwest Research Institute |access-date = 18 February 2018}}</ref>

<ref name="TheSkyLive">{{cite web |title = KBO 2014 MU69 (Ultima Thule) |url = https://theskylive.com/2014mu69-info |work = The Sky Live |url-status = live |archive-url = https://web.archive.org/web/20200205035456/https://theskylive.com/2014mu69-info |archive-date = 5 February 2020 |access-date = 5 February 2020}}</ref>

<ref name="JPLHorizonsX">{{cite web |url = https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=486958 |title = HORIZONS Web-Interface |publisher = Jet Propulsion Laboratory |access-date = 20 June 2019}}</ref>

<ref name="MPC103886">{{cite web |title = M.P.C. 103886 |url = https://minorplanetcenter.net/iau/ECS/MPCArchive/2017/MPC_20170312.pdf |work = Minor Planet Center |publisher = Astronomical International Union |date = 12 March 2017}}</ref>

<ref name="MPC118222">{{cite web |title = M.P.C. 118222 |url = https://minorplanetcenter.net/iau/ECS/MPCArchive/2019/MPC_20191108.pdf |work = Minor Planet Center |publisher = Astronomical International Union |date = 8 November 2019}}</ref>

<ref name="designation">{{cite web |title = New- And Old-Style Minor Planet Designations |url = https://minorplanetcenter.net/iau/info/OldDesDoc.html |work = Minor Planet Center |publisher = International Astronomical Union |access-date = 17 May 2019}}</ref>

<ref name="NASA-new-target-2015">{{cite web |title = NASA's New Horizons Team Selects Potential Kuiper Belt Flyby Target |url = http://www.nasa.gov/feature/nasa-s-new-horizons-team-selects-potential-kuiper-belt-flyby-target |last = Talbert |first = Tricia |publisher = NASA |date = 28 August 2015 |access-date = 4 September 2015 |archive-date = 26 September 2015 |archive-url = https://web.archive.org/web/20150926211423/https://www.nasa.gov/feature/nasa-s-new-horizons-team-selects-potential-kuiper-belt-flyby-target/ }}</ref>

<ref name="Parker2016">{{cite web |title = A World Beyond Pluto: Finding a New Target for New Horizons |url = https://blogs.nasa.gov/pluto/2016/06/28/a-world-beyond-pluto-finding-a-new-target-for-new-horizons/ |last = Parker |first = Alex |website = blogs.nasa.gov |publisher = NASA |date = 28 June 2016}}</ref>

<ref name="NASA-20161018">{{cite web |title = New Horizons: Possible Clouds on Pluto, Next Target is Reddish |url = https://www.nasa.gov/feature/new-horizons-possible-clouds-on-pluto-next-target-is-reddish |last = Talbert |first = Tricia |publisher = NASA |date = 18 October 2016 |access-date = 17 November 2019 |archive-date = 17 June 2019 |archive-url = https://web.archive.org/web/20190617075639/https://www.nasa.gov/feature/new-horizons-possible-clouds-on-pluto-next-target-is-reddish/ }}</ref>

<ref name="FirstOccultation">{{cite web |title = New Mysteries Surround New Horizons' Next Flyby Target |url = https://www.nasa.gov/feature/new-mysteries-surround-new-horizons-next-flyby-target |last = Talbert |first = Tricia |publisher = NASA |date = 5 July 2017 |access-date = 20 July 2017 |archive-date = 21 July 2017 |archive-url = https://web.archive.org/web/20170721232423/https://www.nasa.gov/feature/new-mysteries-surround-new-horizons-next-flyby-target/ }}</ref>

<ref name="Keeter2017">{{cite web |title = New Horizons' Next Target Just Got a Lot More Interesting |url = https://www.nasa.gov/feature/new-horizons-next-target-just-got-a-lot-more-interesting |last = Keeter |first = Bill |publisher = NASA |date = 3 August 2017 |access-date = 4 August 2017 |archive-date = 4 December 2017 |archive-url = https://web.archive.org/web/20171204091149/https://www.nasa.gov/feature/new-horizons-next-target-just-got-a-lot-more-interesting/ }}</ref>

<ref name="nickname">{{cite web |title = Help Nickname New Horizons' Next Flyby Target |url = https://www.nasa.gov/feature/help-nickname-new-horizons-next-flyby-target |last = Talbert |first = Tricia |publisher = NASA |date = 6 November 2017 |quote = NASA's New Horizons mission to Pluto and the Kuiper Belt is looking for your ideas on what to informally name its next flyby destination, a billion miles (1.6 billion kilometers) past Pluto.}}</ref>

<ref name="Ultima Thule">{{cite web |title = New Horizons Chooses Nickname for 'Ultimate' Flyby Target |url = https://www.nasa.gov/feature/new-horizons-chooses-nickname-for-ultimate-flyby-target |last = Talbert |first = Tricia |publisher = NASA |date = 13 March 2018 |access-date = 13 March 2018}}</ref>

<ref name="Keeter2018">{{cite web |title = New Horizons Team Successfully Observes Next Target, Sets the Stage for Ultima Thule Flyby |url = https://www.nasa.gov/feature/new-horizons-team-successfully-observes-next-target-sets-the-stage-for-ultima-thule-flyby |last = Keeter |first = Bill |publisher = NASA |date = 6 September 2018 |access-date = 21 September 2018 |archive-date = 9 October 2018 |archive-url = https://web.archive.org/web/20181009195032/https://www.nasa.gov/feature/new-horizons-team-successfully-observes-next-target-sets-the-stage-for-ultima-thule-flyby/ }}</ref>

<ref name="Keeter2019">{{cite web |title = New Horizons' Evocative Farewell Glance at Ultima Thule |url = https://www.nasa.gov/feature/new-horizons-evocative-farewell-glance-at-ultima-thule |last = Keeter |first = Bill |publisher = NASA |date = 8 February 2019 |access-date = 9 February 2019 |archive-date = 16 December 2019 |archive-url = https://web.archive.org/web/20191216073519/https://www.nasa.gov/feature/new-horizons-evocative-farewell-glance-at-ultima-thule/ }}</ref>

<ref name="bestview">{{cite web |title = New Horizons' Newest and Best-Yet View of Ultima Thule |url = https://solarsystem.nasa.gov/news/819/new-horizons-newest-and-best-yet-view-of-ultima-thule/ |work = NASA Solar System Exploration |publisher = NASA |date = 24 January 2019 |access-date = 17 March 2019}}</ref>

<ref name="NASA-SSE">{{cite web |title = Arrokoth (2014 MU69) – In Depth |url = https://solarsystem.nasa.gov/solar-system/kuiper-belt/arrokoth-2014-mu69/in-depth/ |work = NASA Solar System Exploration |publisher = NASA |date = 19 December 2019 |access-date = 2 February 2020}}</ref>

<ref name="about">{{cite web |title = About Arrokoth |url = http://pluto.jhuapl.edu/Arrokoth/Arrokoth.php |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |archive-url = https://web.archive.org/web/20191106172308/http://pluto.jhuapl.edu/Ultima/Ultima-Thule.php |archive-date= 6 November 2019 |url-status = live}}</ref>

<ref name="LORRI-images">{{cite web |title = LORRI Images from the Arrokoth Flyby |url = http://pluto.jhuapl.edu/soc/Arrokoth-Encounter/ |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |access-date = 2 February 2020}}</ref>

<ref name="jhuapl-20151023">{{cite web |title = Maneuver Moves New Horizons Spacecraft toward Next Potential Target |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151023 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 23 October 2015 |access-date = 5 November 2015 |archive-url = https://web.archive.org/web/20151025193927/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151023 |archive-date= 25 October 2015 |url-status = live}}</ref>

<ref name="jhuapl-20151026b">{{cite web |title = New Horizons Continues Toward Potential Kuiper Belt Target |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151026b |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 26 October 2015 |access-date = 5 November 2015 |archive-url = https://web.archive.org/web/20151119122554/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151026b |archive-date= 19 November 2015 |url-status = live}}</ref>

<ref name="jhuapl20151029">{{cite web |title = On Track: New Horizons Carries Out Third KBO Targeting Maneuver |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151029 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 29 October 2015 |access-date = 5 November 2015 |archive-url = https://web.archive.org/web/20151101181245/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151029 |archive-date= 1 November 2015 |url-status = live}}</ref>

<ref name="jhuapl-20151105">{{cite web |title = NASA's New Horizons Completes Record-Setting Kuiper Belt Targeting Maneuvers |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151105 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 5 November 2015 |access-date = 6 November 2015 |archive-url = https://web.archive.org/web/20151107041827/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20151105 |archive-date= 7 November 2015 |url-status = live}}</ref>

<ref name="SOFIA 1">{{cite web |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170710 |title = SOFIA to Make Advance Observations of Next New Horizons Flyby Object |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 10 July 2017 |archive-url = https://web.archive.org/web/20170713103849/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170710 |archive-date= 13 July 2017 |url-status = live}}</ref>

<ref name="SOFIA 2">{{cite web |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170711 |title = SOFIA in Right Place at Right Time to Study Next New Horizons Flyby Object |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 11 July 2017 |archive-url = https://web.archive.org/web/20170714183039/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170711 |archive-date= 14 July 2017 |url-status = live |access-date = 28 July 2017}}</ref>

<ref name="jhuapl-20170719">{{cite web |title = NASA's New Horizons Team Strikes Gold in Argentina |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170719 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 19 July 2017 |archive-url = https://web.archive.org/web/20170720114913/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170719 |archive-date= 20 July 2017 |url-status = live}}</ref>

<ref name="KBO chasers">{{cite web |title = KBO Chasers |url = http://pluto.jhuapl.edu/Mission/KBO-Chasers.php |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |archive-url = https://web.archive.org/web/20170728074513/http://pluto.jhuapl.edu/Mission/KBO-Chasers.php |archive-date= 28 July 2017 }}</ref>

<ref name="NH-2017">{{cite web |title = The PI's Perspective: The Heroes of the DSN and the 'Summer of MU69' |url = http://pluto.jhuapl.edu/News-Center/PI-Perspectives.php?page=piPerspective_08_08_2017 |last = Stern |first = Alan |author-link = Alan Stern |publisher = Applied Physics Laboratory |date = 8 August 2017 |access-date = 8 August 2017}}</ref>

<ref name="jhuapl-20170906">{{cite web |title = New Horizons Files Flight Plan for 2019 Flyby |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170906 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 6 September 2017 |archive-url = https://web.archive.org/web/20170907170141/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20170906 |archive-date= 7 September 2017 |url-status = live}}</ref>

<ref name="success">{{cite web |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20180804 |title = New Horizons Team Reports Initial Success in Observing Ultima Thule |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 4 August 2018 |access-date = 21 August 2018 |archive-url = https://web.archive.org/web/20180804153845/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20180804 |archive-date= 4 August 2018 |url-status = live}}</ref>

<ref name="jhuapl-20180828">{{cite web |title = Ultima in View: New Horizons Makes First Detection of Kuiper Belt Flyby Target |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20180828 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 28 August 2018 |access-date = 3 September 2018 |archive-url = https://web.archive.org/web/20180829175359/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20180828 |archive-date= 29 August 2018 |url-status = live}}</ref>

<ref name="jhuapl-20181218">{{cite web |title = NASA's New Horizons Spacecraft Takes the Inside Course to Ultima Thule |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20181218 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 18 December 2018 |archive-url = https://web.archive.org/web/20181228035112/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20181218 |archive-date= 28 December 2018 |url-status = live}}</ref>

<ref name="FirstMystery">{{cite web |title = Ultima Thule's First Mystery |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20181220 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 20 December 2018 |access-date = 27 December 2018 |archive-url = https://web.archive.org/web/20190101083653/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20181220 |archive-date= 1 January 2019 |url-status = live}}</ref>

<ref name="explored">{{cite web |title = New Horizons Successfully Explores Ultima Thule |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190101 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 1 January 2019 |access-date = 1 January 2019 |archive-url = https://web.archive.org/web/20190101164301/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190101 |archive-date= 1 January 2019 |url-status = live}}</ref>

<ref name="jhuapl-20190222">{{cite web |title = Spot On! New Horizons Spacecraft Returns Its Sharpest Views of Ultima Thule |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190222 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 22 February 2019 |access-date = 23 February 2019 |archive-url = https://web.archive.org/web/20190223002445/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190222 |archive-date= 23 February 2019 |url-status = live |quote = ...a resolution of about 110 feet (33 meters) per pixel. [...] This processed, composite picture combines nine individual images taken with the Long Range Reconnaissance Imager (LORRI), each with an exposure time of 0.025 seconds...}}</ref>

<ref name="prehistoricpuzzle">{{cite web |title = A Prehistoric Puzzle in the Kuiper Belt |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190318 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 18 March 2019 |access-date = 18 March 2019 |archive-url= https://web.archive.org/web/20190326081447/http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20190318 |archive-date= 26 March 2019 |url-status = live}}</ref>

<ref name="jhuapl-20191112">{{cite web |title = New Horizons Kuiper Belt Flyby Object Officially Named 'Arrokoth' |url = http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20191112 |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 12 November 2019 |access-date = 12 November 2019}}</ref>

<ref name="perspective2021">{{cite web |title = The PI's Perspective: Looking Back, Looking Forward |url = http://pluto.jhuapl.edu/News-Center/PI-Perspectives.php?page=piPerspective_12_17_2021 |first = Alan |last = Stern |publisher = Applied Physics Laboratory |website = pluto.jhuapl.edu |date = 17 December 2021 |access-date = 9 January 2022}}</ref>

<ref name="EPSC2015">{{cite conference |title = The Successful Search for a Post-Pluto KBO Flyby Target for New Horizons Using the Hubble Space Telescope |url = http://meetingorganizer.copernicus.org/EPSC2015/EPSC2015-417.pdf |display-authors = etal |first1 = J. R. |last1 = Spencer |first2 = M. W. |last2 = Buie |first3 = A. H. |last3 = Parker |first4 = H. A. |last4 = Weaver |first5 = S. B. |last5 = Porter |first6 = S. A. |last6 = Stern |conference = European Planetary Science Congress 2015 |volume = 10 |issue = EPSC2015–417 |date = 2015 |bibcode = 2015EPSC...10..417S}}</ref>

<ref name="LPSC1301">{{cite conference |title = Orbits and Accessibility of Potential New Horizons KBO Encounter Targets |url = http://www.hou.usra.edu/meetings/lpsc2015/pdf/1301.pdf |display-authors = 6 |first1 = S. B. |last1 = Porter |first2 = A. H. |last2 = Parker |first3 = M. |last3 = Buie |first4 = J. |last4 = Spencer |first5 = H. |last5 = Weaver |first6 = S. A. |last6 = Stern |first7 = S. |last7 = Benecchi |first8 = A. M. |last8 = Zangari |first9 = A. |last9 = Verbiscer |first10 = S. |last10 = Gwyn |first11 = J-M. |last11 = Petit |first12 = R. |last12 = Sterner |first13 = D. |last13 = Borncamp |first14 = K. |last14 = Noll |first15 = J. J. |last15 = Kavelaars |first16 = D. |last16 = Tholen |first17 = K. N. |last17 = Singer |first18 = M. |last18 = Showalter |first19 = C. |last19 = Fuentes |first20 = G. |last20 = Bernstein |first21 = M. |last21 = Belton |date = March 2015 |conference = 46th Lunar and Planetary Science Conference |publisher = Lunar and Planetary Institute |bibcode = 2015LPI....46.1301P}}</ref>

<ref name="DPS49-7">{{cite conference |title = Debris search around (486958) 2014 MU69: Results from SOFIA and ground-based occultation campaigns |url = https://dps49.abstractcentral.com/s1agxt/com.scholarone.s1agxt.s1agxt/S1A.html?&a=3987&b=1593989&c=43467&d=17&e=36573917&f=17&g=null&h=BROWSE_THE_PROGRAM&i=N&j=N&k=N&l=Y&m=Ni8N2nyNme3AGxIoteIxc0ieCYQ&r=ASjv5PkA6REkbiGTKaRPqg**.c027vkqs1as_ac&n=0&o=1502361552130&q=Y&p=https://dps49.abstractcentral.com&x=Y&z= |display-authors = 6 |first1 = Eliot F. |last1 = Young |first2 = Marc W. |last2 = Buie |first3 = Simon B. |last3 = Porter |first4 = Amanda M. |last4 = Zangari |first5 = S. Alan |last5 = Stern |first6 = Kimberly |last6 = Ennico |first7 = William T. |last7 = Reach |first8 = Enrico |last8 = Pfueller |first9 = Manuel |last9 = Wiedemann |first10 = Wesley C. |last10 = Fraser |first11 = Julio |last11 = Camargo |first12 = Leslie |last12 = Young |first13 = Lawrence H. |last13 = Wasserman |conference = 49th Meeting of the AAS Division for Planetary Sciences |publisher = American Astronomical Society |id = 504.06 |date = October 2017 |bibcode = 2017DPS....4950406Y |access-date = 20 July 2019 |archive-url = https://web.archive.org/web/20181009195156/https://dps49.abstractcentral.com/s1agxt/com.scholarone.s1agxt.s1agxt/S1A.html?&a=3987&b=1593989&c=43467&d=17&e=36573917&f=17&g=null&h=BROWSE_THE_PROGRAM&i=N&j=N&k=N&l=Y&m=Ni8N2nyNme3AGxIoteIxc0ieCYQ&r=ASjv5PkA6REkbiGTKaRPqg%2A%2A.c027vkqs1as_ac&n=0&o=1502361552130&q=Y&p=https%3A%2F%2Fdps49.abstractcentral.com&x=Y&z= |archive-date= 9 October 2018}}</ref>

<ref name="preencounter">{{cite conference |title = Pre-encounter update on (486958) 2014MU69 and occultation results from 2017 and 2018 |first1 = Marc |last1 = Buie |first2 = Simon B. |last2 = Porter |first3 = Anne |last3 = Verbiscer |first4 = Rodrigo |last4 = Leiva |first5 = Brian A. |last5 = Keeney |first6 = Con |last6 = Tsang |first7 = David |last7 = Baratoux |first8 = Michael |last8 = Skrutskie |first9 = François |last9 = Colas |first10 = Josselin |last10 = Desmars |first11 = S. Alan |last11 = Stern |date = 26 October 2018 |conference = 50th Meeting of the AAS Division for Planetary Sciences |publisher = American Astronomical Society |id = 509.06 |bibcode = 2018DPS....5050906B}}</ref>

<ref name="2017 AGU">{{cite conference |title = New Horizons Kuiper Belt Extended Mission |url = http://pluto.jhuapl.edu/News-Center/Press-Conferences/2017-12-12/resources/2017_NH_AGU_PA.pdf |first1 = Jim |last1 = Green |first2 = S. Alan |last2 = Stern |date = 12 December 2017 |conference = 2017 AGU Fall Meeting |publisher = Applied Physics Laboratory |pages = 12–15 |access-date = 26 December 2018 |archive-url = https://web.archive.org/web/20181226234838/http://pluto.jhuapl.edu/News-Center/Press-Conferences/2017-12-12/resources/2017_NH_AGU_PA.pdf |archive-date = 26 December 2018 }}</ref>

<ref name="LPSC1611">{{cite conference |title = A Contact Binary in the Kuiper Belt: The Shape and Pole of (486958) 2014 MU69 |url = https://www.hou.usra.edu/meetings/lpsc2019/pdf/1611.pdf |display-authors = 6 |first1 = S. B. |last1 = Porter |first2 = C. J. |last2 = Bierson |first3 = O. |last3 = Umurhan |first4 = R. A. |last4 = Beyer |first5 = T. A. |last5 = Lauer |first6 = M. W. |last6 = Buie |first7 = A. H. |last7 = Parker |first8 = M. |last8 = Kinczyk |first9 = K. |last9 = Runyon |first10 = W. M. |last10 = Grundy |first11 = J. J. |last11 = Kavelaars |first12 = A. M. |last12 = Zangari |first13 = M. R. |last13 = El-Maarry |first14 = D. T. |last14 = Britt |first15 = J. M. |last15 = Moore |first16 = A. J. |last16 = Verbiscer |first17 = J. W. |last17 = Parker |first18 = C. B. |last18 = Olkin |first19 = H. A. |last19 = Weaver |first20 = J. R. |last20 = Spencer |first21 = S. A. |last21 = Stern |conference = 50th Lunar and Planetary Science Conference 2019 |publisher = Lunar and Planetary Institute |date = March 2019 |bibcode = 2019LPI....50.1611P}}</ref>

<ref name="LPSC1742">{{cite conference |title = Overview of initial results from the reconnaissance flyby of a Kuiper Belt planetesimal: {{mp|2014 MU|69}} |url = https://www.hou.usra.edu/meetings/lpsc2019/pdf/1742.pdf |display-authors = 6 |first1 = S. A. |last1 = Stern |first2 = J. R. |last2 = Spencer |first3 = H. A. |last3 = Weaver |first4 = C. B. |last4 = Olkin |first5 = J. M. |last5 = Moore |first6 = W. |last6 = Grundy |first7 = R. |last7 = Gladstone |first8 = W. B. |last8 = McKinnon |first9 = D. P. |last9 = Cruikshank |first10 = L. A. |last10 = Young |first11 = H. A. |last11 = Elliott |first12 = A. J. |last12 = Verbiscer |first13 = J. Wm. |last13 = Parker |date = 9 January 2019 |conference = 50th Lunar and Planetary Science Conference 2019 |publisher = Lunar and Planetary Institute |arxiv = 1901.02578 |bibcode = 2019LPI....50.1742S}}</ref>

<ref name="LPSC2051">{{cite conference |title = The colors of 486958 {{mp|2014 MU|69}} ("Ultima Thule"): The role of synthetic organic solids (tholins) |url = https://www.hou.usra.edu/meetings/lpsc2019/pdf/2051.pdf |display-authors = 6 |first1 = D. P. |last1 = Cruikshank |first2 = W. M. |last2 = Grundy |first3 = D. T. |last3 = Britt |first4 = E. |last4 = Quirico |first5 = B. |last5 = Schmitt |first6 = F. |last6 = Scipioni |first7 = C. M. |last7 = Dalle Ore |first8 = J. C. |last8 = Cook |first9 = L. |last9 = Gabasova |first10 = S. |last10 = Protopapa |first11 = S. A. |last11 = Stern |first12 = H. A. |last12 = Weaver |first13 = A. J. |last13 = Verbiscer |first14 = J. R. |last14 = Spencer |first15 = C. J. A. |last15 = Howett |first16 = R. P. |last16 = Binzel |first17 = A. H. |last17 = Parker |date = 1 January 2019 |conference = 50th Lunar and Planetary Science Conference |publisher = Lunar and Planetary Institute}}</ref>

<ref name="LPSC3120">{{cite conference |url = https://www.hou.usra.edu/meetings/lpsc2019/pdf/3120.pdf |title = Stellar Occultation Results for (486958) 2014 MU69: A Pathfinding Effort for the New Horizons Flyby |display-authors = 6 |first1 = M. W. |last1 = Buie |first2 = S. B. |last2 = Porter |first3 = P. |last3 = Tamblyn |first4 = D. |last4 = Terrell |first5 = A. J. |last5 = Verbiscer |first6 = B. |last6 = Keeney |first7 = A. M. |last7 = Zangari |first8 = L. H. |last8 = Wasserman |first9 = A. |last9 = Ocampo |first10 = S. A. |last10 = Stern |date = March 2019 |conference = 50th Lunar and Planetary Science Conference 2019 |publisher = Lunar and Planetary Institute |access-date = 27 July 2017}}</ref>

<ref name="EPSC-DPS2019-50">{{cite conference |title = Scarp Retreat on MU69: Evidence and Implications for Composition and Structure |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-50-1.pdf |display-authors = etal |first1 = J. M. |last1 = Moore |first2 = W. B.|last2 = McKinnon |first3 = J. R. |last3 = Spencer |first4 = S. A. |last4 = Stern |first5 = D. |last5 = Britt |first6 = B. J. |last6 = Buratti |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="EPSC-DPS2019-311">{{cite conference |title = The Shape and Pole of (486958) {{mp|2014 MU|69}} |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-311-1.pdf |display-authors = etal |first1 = Simon B. |last1 = Porter |first2 = Ross A. |last2 = Beyer |first3 = James T. |last3 = Keane |first4 = Orkan M. |last4 = Umurhan |first5 = Carver J. |last5 = Bierson |first6 = William M. |last6 = Grundy |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="EPSC-DPS2019-896">{{cite conference |title = Geology and Geophysics of 2014 MU69: New Horizons Flyby Results |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-896-1.pdf |display-authors = etal |first1 = John R. |last1 = Spencer |first2 = Jeffrey M. |last2 = Moore |first3 = William B. |last3 = McKinnon |first4 = S. Alan |last4 = Stern |first5 = Harold A. |last5 = Weaver |first6 = Catherine B. |last6 = Olkin |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="EPSC-DPS2019-1055">{{cite conference |title = Latitude Zones and Seasons on 2014 MU69 'Ultima Thule' |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1055-1.pdf |display-authors = etal |first1 = Alissa M. |last1 = Earle |first2 = R. P. |last2 = Binzel |first3 = J. T. |last3 = Keane |first4 = M. |last4 = Vanatta |first5 = W. M. |last5 = Grundy |first6 = J. M. |last6 = Moore |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="EPSC-DPS2019-1235">{{cite conference |title = Impact craters on 2014 MU69: The geologic history of MU69 and Kuiper belt object size-frequency distributions |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1235-1.pdf |display-authors = etal |first1 = Kelsi N. |last1 = Singer |first2 = William B.|last2 = McKinnon |first3 = John R. |last3 = Spencer |first4 = Sarah |last4 = Greenstreet |first5 = Brett |last5 = Gladman |first6 = Stuart J. |last6 = Robbins |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="EPSC-DPS2019-1387">{{cite conference |title = On the Origin of the Remarkable Contact Binary (486958) {{mp|2014 MU|69}} ("Ultima Thule") |url = https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-1387-7.pdf |display-authors = etal |first1 = William B.|last1 = McKinnon |first2 = James T. |last2 = Keane |first3 = David |last3 = Nesvorný |first4 = Derek R. |last4 = Richardson |first5 = William M. |last5 = Grundy |first6 = Douglas P. |last6 = Hamilton |date = September 2019 |conference = EPSC-DPS Joint Meeting 2019 |publisher = European Planetary Science Congress |volume = 13}}</ref>

<ref name="AGU-P33I-3536">{{cite conference |title = Spindown of 2014 MU69 ("Ultima Thule") by impact of small, cold classical Kuiper belt objects |url = https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/610977 |first1 = Xiaochen |last1 = Mao |first2 = William B. |last2 = McKinnon |first3 = James Tuttle |last3 = Keane |first4 = John R. |last4 = Spencer |first5 = Catherine |last5 = Olkin |first6 = Harold A. |last6 = Weaver |first7 = S. Alan |last7 = Stern |date = 11 December 2019 |conference = AGU Fall Meeting 2019 |publisher = American Geophysical Union |access-date = 1 December 2019}}</ref>

<ref name="LPSC-2019-03-21">{{cite web |url = https://www.youtube.com/watch?v=7m_zpHeTTjc |title = Press Briefing: The developing picture of Ultima Thule |publisher = Lunar and Planetary Institute |website = YouTube |date = 21 March 2019}} 64 minutes</ref>

<ref name="Lakdawalla2014a">{{cite web |title = Hubble to the rescue! The last-ditch effort to discover a Kuiper belt target for New Horizons |url = https://www.planetary.org/blogs/emily-lakdawalla/2014/06170922-hubble-to-the-rescue.html |last = Lakdawalla |first = Emily |author-link = Emily Lakdawalla |publisher = The Planetary Society |date = 17 June 2014}}</ref>

<ref name="Lakdawalla2014b">{{cite web |title = Finally! New Horizons has a second target |url = http://www.planetary.org/blogs/emily-lakdawalla/2014/10151024-finally-new-horizons-has-a-kbo.html |last = Lakdawalla |first = Emily |author-link = Emily Lakdawalla |publisher = The Planetary Society |date = 15 October 2014 |archive-url = https://web.archive.org/web/20141015230432/http://www.planetary.org/blogs/emily-lakdawalla/2014/10151024-finally-new-horizons-has-a-kbo.html |archive-date = 15 October 2014 |url-status = live}}</ref>

<ref name="Lakdawalla2015">{{cite web |title = New Horizons extended mission target selected |url = http://www.planetary.org/blogs/emily-lakdawalla/2015/09011608-new-horizons-extended-mission-pt1.html |last = Lakdawalla |first = Emily |author-link = Emily Lakdawalla |publisher = The Planetary Society |date = 1 September 2015}}</ref>

<ref name="Science Team Meeting">{{cite web |title = New Horizons prepares for encounter with 2014 MU69 |url = http://www.planetary.org/blogs/emily-lakdawalla/2018/0124-new-horizons-prepares-for-2014mu69.html |last = Lakdawalla |first = Emily |author-link = Emily Lakdawalla |publisher = The Planetary Society |date = 24 January 2018 |access-date = 25 January 2018}}</ref>

<ref name="Davis2018">{{cite web |title = 'Everything about this flyby is tougher': New Horizons just over 100 days from Ultima Thule |url = https://www.planetary.org/blogs/jason-davis/2018/nh-ut-100days.html |last = Davis |first = Jason |publisher = The Planetary Society |date = 19 September 2018 |access-date = 4 February 2020}}</ref>

<ref name="WhatToExpect">{{cite web |title = What to Expect When New Horizons Visits 2014 MU69, Ultima Thule, And When We Will Get Pictures |url = http://www.planetary.org/blogs/emily-lakdawalla/2018/what-to-expect-new-horizons-mu69-ultima-thule.html |last = Lakdawalla |first = Emily |publisher = The Planetary Society |date = 17 December 2018 |access-date = 27 December 2018}}</ref>

<ref name="Witze2014">{{cite journal |title = Pluto-bound probe faces crisis |last = Witze |first = Alexandra |journal = Nature |volume = 509 |issue = 7501 |pages = 407–408 |date = 22 May 2014 |doi = 10.1038/509407a|pmid = 24848039 |bibcode = 2014Natur.509..407W |s2cid = 4468314 |doi-access= free }}</ref>

<ref name="hubble_2_KBOs">{{cite web |title = Hubble Survey Finds Two Kuiper Belt Objects to Support New Horizons Mission |url = https://science.nasa.gov/asset/hubble/hubble-survey-finds-two-kuiper-belt-objects-to-support-new-horizons-mission/ |website = NASA Science |publisher = NASA |date = 1 July 2014}}</ref>

<ref name="potential-KBOs-2014">{{cite web |title = NASA's Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission |url = http://hubblesite.org/newscenter/archive/releases/2014/47/ |website = HubbleSite |publisher = Space Telescope Science Institute |date = 15 October 2014}}</ref>

<ref name="TheOuterSanctum">{{cite web |url = https://cdan4th.wordpress.com/2017/07/07/mu69occ_4/ |title = The Case of the Dog that Didn't Bark in the Night |work = The Outer Sanctum |date = 7 July 2017 |archive-url = https://web.archive.org/web/20170709201906/https://cdan4th.wordpress.com/2017/07/07/mu69occ_4/ |archive-date= 9 July 2017 |url-status = live}}</ref>

<ref name="MU69occ">{{cite web |title = These are the 2017 stellar occultation predictions for the object 2014 MU69. |url = http://www.boulder.swri.edu/MU69_occ/ |publisher = Southwest Research Institute |access-date = 27 July 2017}}</ref>

<ref name="August4preparation">{{cite news |title = New Horizons team prepares for stellar occultation ahead of Ultima Thule flyby |url = http://www.spacedaily.com/reports/New_Horizons_team_prepares_for_stellar_occultation_ahead_of_Ultima_Thule_flyby_999.html |work = Space Daily |date = 2 August 2018 |access-date = 2 August 2018}}</ref>

<ref name="AFIPS">{{cite web |title = AFIPS participation to NASA expedition in Senegal |url = https://africapss.org/research/afips-participation-to-nasa-expedition-in-senegal/ |year = 2018 |publisher = Africa Initiative for Planetary and Space Sciences |access-date = 21 August 2018 |archive-date = 22 August 2018 |archive-url = https://web.archive.org/web/20180822113857/https://africapss.org/research/afips-participation-to-nasa-expedition-in-senegal/ }}</ref>

<ref name="Planetaria">{{cite web |url = http://planetaria.ca/2018/08/08/new-horizons-team-successfully-observes-new-stellar-occultation-of-ultima-thule/ |title = New Horizons team successfully observes new stellar occultation of Ultima Thule |last = Anderson |first = Paul Scott |work = Planetaria |date = 8 August 2018 |access-date = 15 January 2019 |archive-date = 4 December 2020 |archive-url = https://web.archive.org/web/20201204141132/http://planetaria.ca/2018/08/08/new-horizons-team-successfully-observes-new-stellar-occultation-of-ultima-thule/ }}</ref>

<ref name="OccultationRevisited">{{cite news |url = https://www.nasaspaceflight.com/2019/01/2014-mu69-contact-binary-first-new-horizons-returns/ |title = 2014 MU69 revealed as a contact binary in first New Horizons data returns |last = Gebhardt |first = Chris |website = NASASpaceFlight.com |date = 2 January 2019 |access-date = 5 January 2019}}</ref>

<ref name="Beatty20190104">{{cite magazine |title = New Views of Two-Lobed "Ultima Thule" |url = https://www.skyandtelescope.com/astronomy-news/amazing-views-of-ultima-thule/ |last = Beatty |first = Kelly |magazine = Sky & Telescope |date = 4 January 2019 |access-date = 22 February 2019}}</ref>

<ref name="lauer-sciam">{{cite magazine |title = The Moment We First Saw Ultima Thule Up Close |url = https://blogs.scientificamerican.com/observations/the-moment-we-first-saw-ultima-thule-up-close/ |first1 = Tod R. |last1 = Lauer |author-link1 = Tod R. Lauer |first2 = Henry |last2 = Throop |author-link2 = Henry Throop |magazine = Scientific American |publisher = Springer Nature |date = 17 January 2019 |access-date = 26 January 2019}}</ref>

<ref name="Grossman20190129">{{cite news |title = The latest picture of Ultima Thule reveals a remarkably smooth face |url = https://www.sciencenews.org/article/latest-picture-ultima-thule-reveals-remarkably-smooth-face |last = Grossman |first = Lisa |magazine = Science News |publisher = Society for Science & the Public |date = 29 January 2019 |access-date = 17 March 2019}}</ref>

<ref name="Beatty20190319">{{cite magazine |title = New Results Probe the Origin of "Ultima Thule" |url = https://www.skyandtelescope.com/astronomy-news/new-results-probe-the-origin-of-ultimate-thule/ |last = Beatty |first = Kelly |magazine = Sky & Telescope |date = 19 March 2019 |access-date = 19 March 2019}}</ref>

<ref name="NYT-2017">{{cite news |title = Chasing Shadows for a Glimpse of a Tiny World Beyond Pluto |url = https://www.nytimes.com/2017/08/08/science/new-horizons-nasa-pluto-mu69-occultations.html |last = Chang |first = Kenneth |work = The New York Times |date = 8 August 2017 |access-date = 9 August 2017}}</ref>

<ref name="NYT-20181230">{{cite news |title = A Journey Into the Solar System's Outer Reaches, Seeking New Worlds to Explore |url = https://www.nytimes.com/2018/12/30/science/nasa-new-horizons-kuiper-belt.html |last = Chang |first = Kenneth |work = The New York Times |date = 30 December 2018 |access-date = 30 December 2018}}</ref>

<ref name="NYT-20181231">{{cite news |title = NASA's New Horizons Will Visit Ultima Thule on New Year's Day |url = https://www.nytimes.com/2018/12/31/science/ultima-thule-pictures-new-horizons.html |last = Chang |first = Kenneth |work = The New York Times |date = 31 December 2018 |access-date = 31 December 2018}}</ref>

<ref name="NYT-20190102-kc">{{cite news |title = NASA's New Horizons Mission Releases Snowman-like Picture of Ultima Thule |url = https://www.nytimes.com/2019/01/02/science/ultima-thule-pictures-new-horizons.html |last = Chang |first = Kenneth |work = The New York Times |date = 2 January 2019 |access-date = 2 January 2019}}</ref>

<ref name="NYT-20190103-kc">{{cite news |title = What We've Learned About Ultima Thule From NASA's New Horizons Mission |url = https://www.nytimes.com/2019/01/03/science/ultima-thule-pictures-new-horizons.html |last = Chang |first = Kenneth |work = The New York Times |date = 3 January 2019 |access-date = 4 January 2019}}</ref>

<ref name="SN-20190104">{{cite web |title = Ultima Thule: Preliminary Science Results from New Horizons |url = http://www.sci-news.com/space/ultima-thule-preliminary-science-results-06786.html |date = 4 January 2019 |website = Sci-News.com |access-date = 5 January 2019}}</ref>

<ref name="NYT-20190318kc">{{cite news |title = How Ultima Thule Is Like a Sticky, Pull-Apart Pastry |url = https://www.nytimes.com/2019/03/18/science/ultima-thule-new-horizons.html |last = Chang |first = Kenneth |work = The New York Times |date = 18 March 2019 |access-date = 19 March 2019}}</ref>

<ref name="Wall2014">{{cite web |title = Hubble Telescope Spots Post-Pluto Targets for New Horizons Probe |url = http://www.space.com/27445-hubble-telescope-new-horizons-kuiper-belt.html |last = Wall |first = Mike |website = Space.com |date = 15 October 2014 |archive-url = https://web.archive.org/web/20141015233156/http://www.space.com/27445-hubble-telescope-new-horizons-kuiper-belt.html |archive-date= 15 October 2014}}</ref>

<ref name="Wall2018">{{cite web |title = New Horizons, Meet Ultima Thule: Probe's Next Target Gets a Nickname |url = https://www.space.com/39963-new-horizons-flyby-target-nickname.html |last = Wall |first = Mike |website = Space.com |date = 14 March 2018}}</ref>

<ref name="SP-20190104">{{cite web |title = The Hunt Is On for Moons Around Ultima Thule |url = https://www.space.com/42894-ultima-thule-moons-new-horizons.html |last = Wall |first = Mike |website = Space.com |date = 4 January 2019 |access-date = 4 January 2019}}</ref>

<ref name="SPC-20190318">{{cite web |title = NASA's New Horizons Reveals Geologic 'Frankenstein' That Formed Ultima Thule |url = https://www.space.com/new-horizons-ultima-thule-flyby-geologic-frankenstein.html |last = Bartels |first = Meghan |website = Space.com |date = 18 March 2019 |access-date = 18 March 2019}}</ref>

<ref name="Delsanti2006">{{cite book |first1 = Audrey |last1 = Delsanti |first2 = David |last2 = Jewitt |title = Solar System Update |year = 2006 |publisher = Springer |editor1-first = P. |editor1-last = Blonde |editor2-first = J. |editor2-last = Mason |chapter = The Solar System Beyond The Planets |chapter-url = http://www2.ess.ucla.edu/~jewitt/papers/2006/DJ06.pdf |pages = 267–293 |doi = 10.1007/3-540-37683-6_11 |bibcode = 2006ssu..book..267D |isbn = 3-540-26056-0 |archive-url = https://web.archive.org/web/20070925203400/http://www.ifa.hawaii.edu/faculty/jewitt/papers/2006/DJ06.pdf |archive-date = 25 September 2007}}</ref>

<ref name="Buie">{{cite web |title = New Horizons HST KBO Search Results: Status Report |url = http://www.stsci.edu/institute/stuc/oct-2014/New-Horizons.pdf |archive-url = https://wayback.archive-it.org/all/20150727213348/http://www.stsci.edu/institute/stuc/oct-2014/New-Horizons.pdf |archive-date = 27 July 2015 |last = Buie |first = Marc W. |author-link = Marc W. Buie |publisher = Space Telescope Science Institute |page = 23 |date = 15 October 2014 }}</ref>

<ref name="MU69occ rationale">{{cite journal |title = Mission Support of the New Horizons {{mp|2014 MU|69}} Encounter via Stellar Occultations |url = http://www.boulder.swri.edu/MU69_occ/case.html |last = Young |first = Eliot |journal = SOFIA Proposal |volume = 5 |page = 168 |year = 2016 |access-date = 27 July 2017 |bibcode = 2016sofi.prop..168Y}}</ref>

<ref name="hst15450">{{cite web |url = https://archive.stsci.edu/proposal_search.php?id=15450&mission=hst |title = New Horizons support observations for 2014MU69 encounter – HST Proposal 15450 |last = Buie |first = Marc W. |work = Mikulski Archive for Space Telescope |publisher = Space Telescope Science Institute |date = 9 February 2018 |access-date = 9 March 2018}}</ref>

<ref name="Stern-Extended">{{cite journal |title = The New Horizons Kuiper Belt Extended Mission |display-authors = etal |first1 = S. A. |last1 = Stern |first2 = H. A. |last2 = Weaver |first3 = J. A. |last3 = Spencer |first4 = H. A. |last4 = Elliott |journal = Space Science Reviews |publisher = Springer Link |volume = 214 |issue = 4 |id = 77 |page = 23 |date = June 2018 |doi = 10.1007/s11214-018-0507-4 |arxiv = 1806.08393 |bibcode = 2018SSRv..214...77S|s2cid = 119506499 }}</ref>

<ref name="Kammer2018">{{cite journal |title = Probing the Hill Sphere of (486958) {{mp|2014 MU|69}}: HST FGS Observations during the 2017 July 17 Stellar Occultation |display-authors = 6 |first1 = Joshua A. |last1 = Kammer |first2 = Tracy M. |last2 = Becker |first3 = Kurt D. |last3 = Retherford |first4 = S. Alan |last4 = Stern |first5 = Catherine B. |last5 = Olkin |first6 = Marc W. |last6 = Buie |first7 = John R. |last7 = Spencer |first8 = Amanda S. |last8 = Bosh |first9 = Lawrence H. |last9 = Wasserman |journal = The Astronomical Journal |publisher = American Astronomical Society |volume = 156 |page = 72 |number = 2 |date = 27 July 2018 |doi = 10.3847/1538-3881/aacdf8 |arxiv = 1806.09684 |bibcode = 2018AJ....156...72K|s2cid = 118993544 |doi-access = free }}</ref>

<ref name="necklace">{{cite arXiv |title = Ultima Thule (486958; 2014 MU69): Necklace, Composition, Rotation, Formation |last = Katz |first = J. I. |eprint = 1902.00997 |date = 4 February 2019 |class = astro-ph.EP}}</ref>

<ref name="Prentice2019">{{cite arXiv |title = Ultima Thule: a Prediction for the Origin, Bulk Chemical Composition, and Physical Structure, submitted prior to the New Horizons Spacecraft 100 Pixel LORRI Data Return |last = Prentice |first = Andrew J. R. |eprint = 1901.02850 |date = 9 January 2019 |class = astro-ph.EP}}</ref>

<ref name="Benecchi2019a">{{cite journal |title = The HST Lightcurve of (486958) {{mp|2014 MU|69}} |last1 = Benecchi |first1 = Susan D. |last2 = Buie |first2 = Marc W. |last3 = Porter |first3 = Simon Bernard |last4 = Spencer |first4 = John R. |last5 = Verbiscer|first5 = Anne J. |last6 = Stern |first6 = S. Alan |last7 = Zangari |first7 = Amanda Marie |last8 = Parker |first8 = Alex |last9 = Noll |first9 = Keith S. |date = December 2019 |journal = Icarus |volume = 334 |pages = 11–21 |doi = 10.1016/j.icarus.2019.01.023 |arxiv = 1812.04758 |bibcode = 2017DPS....4950407B|s2cid = 119388343 }}</ref>

<ref name="Benecchi2019b">{{cite journal |title = The color and binarity of (486958) {{mp|2014 MU|69}} and other long-range New Horizons Kuiper Belt targets |display-authors = etal |first1 = S. D. |last1 = Benecchi |first2 = D. |last2 = Borncamp |first3 = A. H. |last3 = Parker |first4 = M. W. |last4 = Buie |first5 = K. S. |last5 = Noll |first6 = R. P. |last6 = Binzel |journal = Icarus |volume = 334 |pages = 22–29 |date = December 2019 |doi = 10.1016/j.icarus.2019.01.025 |arxiv = 1812.04752|s2cid = 119192900 }}</ref>

<ref name="craterdensity">{{cite journal |title = Crater Density Predictions for New Horizons flyby target 2014 MU69 |first1 = Sarah |last1 = Greenstreet |first2 = Brett |last2 = Gladman |first3 = William B. |last3 = McKinnon |first4 = J. J. |last4 = Kavelaars |first5 = Kelsi N. |last5 = Singer |journal = The Astrophysical Journal Letters |volume = 872 |issue = 1 |id = L5 |page = 6 |date = February 2019 |doi = 10.3847/2041-8213/ab01db |arxiv = 1812.09785 |bibcode = 2019ApJ...872L...5G|s2cid = 119210250 |doi-access = free }}</ref>

<ref name="eaaw9771">{{cite journal |title = Initial results from the New Horizons exploration of {{mp|2014 MU|69}}, a small Kuiper Belt object |display-authors = etal |first1 = S. A. |last1 = Stern |first2 = H. A. |last2 = Weaver |first3 = J. R. |last3 = Spencer |first4 = C. B. |last4 = Olkin |first5 = G. R. |last5 = Gladstone |first6 = W. M. |last6 = Grundy |first7 = J. M. |last7 = Moore |first8 = D. P. |last8 = Cruikshank |first9 = H. A. |last9 = Elliott |first10 = W. B. |last10 = McKinnon |journal = Science |date = 17 May 2019 |volume = 364 |issue = 6441 |article-number = aaw9771 |id = aaw9771 |doi = 10.1126/science.aaw9771 |arxiv = 2004.01017 |bibcode = 2019Sci...364.9771S |pmid = 31097641|s2cid = 156055370 }}</ref>

<ref name="Thirouin2019">{{cite journal |title = Colors of Trans-Neptunian Contact Binaries |first1 = Audrey |last1 = Thirouin |first2 = Scott S. |last2 = Sheppard |date = August 2019 |journal = The Astronomical Journal |volume = 158 |issue = 2 |page = 53 |doi = 10.3847/1538-3881/ab27bc |arxiv = 1906.02071 |bibcode = 2019AJ....158...53T|s2cid = 174799278 |doi-access = free }}</ref>

<ref name="Buie2020">{{cite journal |title = Size and Shape Constraints of (486958) Arrokoth from Stellar Occultations |display-authors = etal |first1 = Marc W. |last1 = Buie |first2 = Simon B. |last2 = Porter |first3 = Peter |last3 = Tamblyn |first4 = Dirk |last4 = Terrell |first5 = Alex H. |last5 = Parker |first6 = David |last6 = Baratoux |journal = The Astronomical Journal |date = January 2020 |volume = 159 |issue = 4 |page = 130 |doi = 10.3847/1538-3881/ab6ced |arxiv = 2001.00125|bibcode = 2020AJ....159..130B |s2cid = 209531955 |doi-access = free }}</ref>

<ref name="eaay3705">{{cite journal |title = Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth |display-authors = etal |first1 = W. M. |last1 = Grundy |first2 = M. K. |last2 = Bird |first3 = D. T. |last3 = Britt |first4 = J. C. |last4 = Cook |first5 = D. P. |last5 = Cruikshank |first6 = C. J. A. |last6 = Howett |journal = Science |date = 13 February 2020 |volume = 367 |issue = 6481 |article-number = eaay3705 |id = aay3705 |doi = 10.1126/science.aay3705 |arxiv = 2002.06720 |issn = 1095-9203 |pmid = 32054693|bibcode = 2020Sci...367.3705G |s2cid = 211110588 }}</ref>

<ref name="aay3999">{{cite journal |title = The geology and geophysics of Kuiper Belt object (486958) Arrokoth |display-authors = etal |first1 = J. R. |last1 = Spencer |first2 = S. A. |last2 = Stern |first3 = J. M. |last3 = Moore |first4 = H. A. |last4 = Weaver |first5 = K. N. |last5 = Singer |first6 = C. B. |last6 = Olkin |journal = Science |date = 13 February 2020 |volume = 367 |issue = 6481 |article-number = eaay3999 |id = aay3999 |doi = 10.1126/science.aay3999 |arxiv = 2004.00727 |issn = 1095-9203 |pmid = 32054694|bibcode = 2020Sci...367.3999S |s2cid = 211113071 }}</ref>

<ref name="eaba6889">{{cite journal |title = A deep dive into the abyss |display-authors = etal |first = David C. |last = Jewitt |journal = Science |date = 13 February 2020 |volume = 367 |issue = 6481 |id = eaba6889 |pages = 980–981 |doi = 10.1126/science.aba6889 |issn = 1095-9203 |pmid = 32054696|bibcode = 2020Sci...367..980J |s2cid = 211112449 }}</ref>

<ref name="Lyra2020">{{cite journal |title = Evolution of MU69 from a binary planetesimal into contact by Kozai-Lidov oscillations and nebular drag |first1 = Wladmir |last1 = Lyra |first2 = Andrew N. |last2 = Youdin |first3 = Anders |last3 = Johansen |journal = Icarus |year = 2021 |volume = 356 |article-number = 113831 |doi = 10.1016/j.icarus.2020.113831 |arxiv = 2003.00670 |bibcode = 2021Icar..35613831L |s2cid = 211677898 }}</ref>

<ref name="Hofgartner2020">{{cite journal |title = Photometry of Kuiper Belt Object (486958) Arrokoth from New Horizons LORRI |display-authors = etal |first1 = Jason D. |last1 = Hofgartner |first2 = Bonnie J. |last2 = Buratti |first3 = Susan D. |last3 = Benecchi |first4 = Ross A. |last4 = Beyer |first5 = Andrew |last5 = Cheng |first6 = James T. |last6 = Keane |date = 3 March 2020 |journal = Icarus |volume = 356 |article-number = 113723 |doi = 10.1016/j.icarus.2020.113723 |arxiv = 2003.01224|s2cid = 211817979 }}</ref>

<ref name="Marohnic2020">{{cite journal |title = Constraining the final merger of contact binary (486958) Arrokoth with soft-sphere discrete element simulations |display-authors = etal |first1 = J. C. |last1 = Marohnic |first2 = D. C. |last2 = Richardson |first3 = W. B. |last3 = McKinnon |first4 = H. F. |last4 = Agrusa |first5 = J. V. |last5 = DeMartini |first6 = A. F. |last6 = Cheng |journal = Icarus |date = May 2020 |volume = 356 |article-number = 113824 |arxiv = 2005.06525 |doi = 10.1016/j.icarus.2020.113824 |bibcode = 2021Icar..35613824M|s2cid = 218628659 }}</ref>

<ref name="IAU-F2-report">{{cite web |title = Commission F2 Annual Report (2019) |url = https://www.iau.org/static/science/scientific_bodies/working_groups/98/wg-psn-annual-report-2019.pdf |first = Rita |last = Schulz |editor-first = J. |editor-last= Lissauer |work = Working Group for Planetary System Nomenclature |publisher = International Astronomical Union |date = 4 May 2020 |access-date = 14 October 2020}}</ref> <ref name="Lisse2020">{{cite journal |title = On the Origin and Thermal Stability of Arrokoth's and Pluto's Ices |display-authors = etal |first1 = C. M. |last1 = Lisse |first2 = L. A. |last2 = Young |first3 = D. P. |last3 = Cruikshank |first4 = S. A. |last4 = Sandford |first5 = B. |last5 = Schmitt |first6 = S. A. |last6 = Stern |journal = Icarus |date = September 2020 |volume = 356 |article-number = 114072 |arxiv = 2009.02277 |doi = 10.1016/j.icarus.2020.114072 |bibcode = 2021Icar..35614072L|s2cid = 221507718 }}</ref>

<ref name="Zhao2020">{{cite journal |title = Sublimation as an effective mechanism for flattened lobes of (486958) Arrokoth |first1 = Y. |last1 = Zhao |first2 = L. |last2 = Rezac |first3 = Y. |last3 = Skorov |first4 = S. C. |last4 = Hu |first5 = N. H. |last5 = Samarasinha |first6 = J.-Y. |last6 = Li |journal = Nature Astronomy |date = October 2020 |volume = 5 |issue = 2 |pages = 139–144 |arxiv = 2010.06434 |doi = 10.1038/s41550-020-01218-7 |s2cid = 222310433 }}</ref>

<ref name="Mahjoub2021">{{cite journal |title = Effect of H<sub>2</sub>S on the Near-infrared Spectrum of Irradiation Residue and Applications to the Kuiper Belt Object (486958) Arrokoth |display-authors = etal |first1 = Ahmed |last1 = Mahjoub |first2 = Michael E. |last2 = Brown |first3 = Michael J. |last3 = Poston |first4 = Robert |last4 = Hodyss |first5 = Bethany L. |last5 = Ehlmann |first6 = Jordana |last6 = Blacksberg |journal = The Astrophysical Journal Letters |date = June 2021 |volume = 914 |issue = 2 |pages = L31 |doi = 10.3847/2041-8213/ac044b|bibcode = 2021ApJ...914L..31M |s2cid = 235478458 |url = https://resolver.caltech.edu/CaltechAUTHORS:20210629-165229618 |doi-access = free }}</ref>

<ref name="Keane2022">{{cite journal |display-authors = etal |first1 = James T. |last1 = Keane |first2 = Simon B. |last2 = Porter |first3 = Ross |last3 = Beyer |first4 = Orkan M. |last4 = Umurhan |first5 = William B. |last5 = McKinnon |first6 = Jeffrey M. |last6 = Moore |title = The Geophysical Environment of (486958) Arrokoth— A Small Kuiper Belt Object Explored by New Horizons |journal = Journal of Geophysical Research: Planets |date = June 2022 |volume = 127 |issue = 6 |article-number = e2021JE007068 |id = e07068 |doi = 10.1029/2021JE007068 |bibcode = 2022JGRE..12707068K |s2cid = 248847707|url = https://resolver.caltech.edu/CaltechAUTHORS:20220712-629937000 }}</ref>

<ref name="McKinnon2022">{{cite journal |display-authors = etal |first1 = William B. |last1 = McKinnon |first2 = Xiaochen |last2 = Mao |first3 = P. M. |last3 = Schenk |first4 = K. N. |last4 = Singer |first5 = S. J. |last5 = Robbins |first6 = O. L. |last6 = White |title = Snow Crash: Compaction Craters on (486958) Arrokoth and Other Small KBOs, With Implications |journal = Geophysical Research Letters |date = July 2022 |volume = 49 |issue = 13 |article-number = e2022GL098406 |id = e98406 |doi = 10.1029/2022GL098406 |bibcode = 2022GeoRL..4998406M |s2cid = 249876420|doi-access = free }}</ref>

<ref name="Porter2024">{{cite web |display-authors = etal |first1 = Simon B. |last1 = Porter |first2 = Kelsi N. |last2 = Singer |first3 = Paul M. |last3 = Schenk |first4 = Anne J. |last4 = Verbiscer |first5 = Susan D. |last5 = Benecchi |first6 = John R. |last6 = Spencer |editor-first1 = Caden |editor-first2 = Brian |editor-first3 = M. Katherine |editor-first4 = Brian |editor-first5 = Joel Wm. |editor-first6 = Kelsi N. |editor-last1 = Gobat |editor-last2 = Enke |editor-last3 = Crombie |editor-last4 = Keeney |editor-last5 = Parker |editor-last6 = Singer |title = The Shape of (486958) Arrokoth |url = https://pdssbn.astro.umd.edu/holdings/pds4-nh_derived-v3.0/arrokoth_shapemodel_porter2024/porteretal2024b.pdf |publisher = NASA Planetary Data System |doi = 10.26007/97r3-1e19 |date = 2024-06-19 |accessdate = 2025-12-05 |url-status = live |archive-url = https://web.archive.org/web/20250406040827/https://pdssbn.astro.umd.edu/holdings/pds4-nh_derived-v3.0/arrokoth_shapemodel_porter2024/porteretal2024b.pdf |archive-date = 2025-04-06}}</ref>

}}

== External links == {{Commons category}} * [https://solarsystem.nasa.gov/solar-system/kuiper-belt/arrokoth-2014-mu69/overview/ Arrokoth ({{mp|2014 MU|69}}): Most Distant Object Explored Up Close] at NASA Solar System Exploration * [http://pluto.jhuapl.edu/Arrokoth/Arrokoth.php About Arrokoth ({{mp|2014 MU|69}})] * [http://pluto.jhuapl.edu/soc/Arrokoth-Encounter/ LORRI Images from the Arrokoth Flyby] * {{AstDys|486958}} * {{JPL small body}}

{{2018 in space}} {{2019 in space}} {{Minor planets navigator | |number=486958 | }} {{Small Solar System bodies}} {{NH1}} {{Authority control}}

{{DEFAULTSORT:486958}} Category:486958 Arrokoth 20140626 Category:Cold classical Kuiper belt objects Category:Contact binary (small Solar System body) Arrokoth Category:Discoveries by the New Horizons KBO Search Category:Discoveries by the Hubble Space Telescope Category:Minor planets visited by spacecraft Arrokoth Category:New Horizons Category:Objects observed by stellar occultation Category:2019 in spaceflight Category:Articles containing video clips Arrokoth Category:Pamunkey