Gonggong_(dwarf_planet)

# Gonggong (dwarf planet)  **Microsim — three.js (Wikitube framework):** *Gonggong in the Solar System explorer* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?obj=Gonggong&embed=1" data-title="Gonggong in the Solar System explorer"></div> *The Solar System explorer locked on this article's state (`?obj=Gonggong`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.*  *Try: drag the year slider back to 1857 to find Gonggong near its closest point to the Sun, about 33 AU out, then forward to 2050 to see it far out on its way towards its 101 AU aphelion; drag to an edge-on view to see its 31° tilt; set the speed to 100 years/s and watch one lap take about five and a half seconds.* **Gonggong** (minor-planet number 225088) is a [[Dwarf_planet|dwarf planet]] of the [[Scattered_disc|scattered disc]] beyond [[Neptune]], about 1,230 km across, roughly the size of Pluto's moon [[Charon_(moon)|Charon]].[^kiss2019][^fs-pluto] Its orbit is both eccentric and steeply inclined, taking it between about 33 and 101 AU from the [[Sun]], and the Deep Ecliptic Survey places it in a 3:10 resonance with Neptune.[^sbdb][^buie2019] Megan Schwamb, Michael Brown and David Rabinowitz discovered it at Palomar Observatory in July 2007, and it was known for more than a decade by its provisional designation, 2007 OR10.[^mpec2009][^schwamb2019a] Gonggong's surface is among the reddest in the Kuiper belt and carries [[Water|water]] ice; its colour is usually attributed to reddish organic compounds made by radiation from methane.[^brown2011][^emery2024] It turns slowly, once in about 22 hours, perhaps braked by tides from its moon, Xiangliu.[^pal2016][^kiss2017] Both bodies were named in 2020, after figures of Chinese mythology: Gònggōng, a water god who caused floods and tilted the Earth, and Xiangliu, his nine-headed serpent minister; the dwarf planet's name was chosen in a public poll.[^schwamb2019b][^mpc] The explorer at the top of this page is locked on Gonggong: it draws the dwarf planet's orbit from JPL's Small-Body Database, reaching 100.6 [[Astronomical_unit|AU]] at aphelion; Xiangliu is not drawn at this scale.[^sbdb] ## History ### Discovery Gonggong was discovered on 17 July 2007 in the Palomar Distant Solar System Survey, a search with the Samuel Oschin telescope at Palomar Observatory for distant bodies in the region of [[Sedna_(dwarf_planet)|Sedna]], beyond 50 AU, designed to detect the slow motion of objects out to at least 1,000 AU.[^schwamb2009][^schwamb2010] Schwamb, then a graduate student of Brown at Caltech, found it by comparing images of the same field and noticing its slow drift, a sign of great distance; the survey formed part of her doctoral thesis.[^schwamb2019a][^sciencedaily2011] The discovery was announced in a Minor Planet Electronic Circular on 7 January 2009, with the provisional designation 2007 OR10, marking it as the 267th object reported in the second half of July 2007.[^mpec2009] Searches of older images found it on two plates, the earliest taken at La Silla Observatory on 19 August 1985, and it received the minor-planet number 225088 on 2 November 2009.[^mpc][^lowe] ### Name and symbol Brown at first nicknamed the object "Snow White", expecting it to be a white, icy fragment of the [[Haumea]] family. It turned out to be one of the reddest bodies known, and the nickname was dropped.[^brown2011blog][^brown2009blog] Brown did not propose a formal name at first, regarding the object as unremarkable; the detection of water ice and possible methane in 2011, and the large size suggested by Kepler measurements in 2016, made it the largest unnamed body in the Solar System and a stronger candidate for a name.[^brown2009blog][^sciencedaily2011][^jpl2016] In 2019 the discoverers held an online poll with three candidates allowed by the IAU's rules for such objects: Gonggong from Chinese, Holle from German and Vili from Norse mythology. All three were linked to water, ice, snow or the colour red, and each came with companion figures that could later name the moon.[^iau2019][^schwamb2019a] Gonggong won with about 46 percent of roughly 280,000 votes, announced on 29 May 2019; the IAU's Committee on Small Body Nomenclature accepted the name, and the Minor Planet Center published it on 5 February 2020.[^schwamb2019b][^mpc121135] A symbol, designed by Denis Moskowitz by combining the Chinese character 共 with a snake's tail, was added to Unicode in 2022; it is used mainly by astrologers.[^unicode2022] ## Orbit Gonggong's orbit has a semi-major axis of about 66.9 AU, an eccentricity of 0.50 and an inclination of 30.9° to the [[Ecliptic|ecliptic]], so its distance from the Sun ranges from about 33.1 AU at perihelion to 100.6 AU at aphelion; one circuit takes about 548 years.[^sbdb] It passed perihelion in 1857 and is now heading outward, towards an aphelion around 2134.[^horizons][^grundy2020] Among the probable dwarf planets, its period is exceeded only by those of [[Eris_(dwarf_planet)|Eris]] and Sedna, and its inclination only by Eris's.[^sbdb] The Minor Planet Center lists it as a scattered-disc object, and the Deep Ecliptic Survey classifies it as a [[Resonant_trans-Neptunian_object|resonant object]], completing three orbits for every ten of Neptune's, the 3:10 ratio (derived: 3 × 548 ≈ 1,644 years, against 10 × 164.8 ≈ 1,648 years).[^mpc][^buie2019] Its perihelion, at 33 AU, is close enough to Neptune's orbit that the planet can still affect it.[^sbdb] In 2021 Gonggong was about 89 AU from the Sun and receding at about 1.1 km/s, which made it more distant than Sedna, a position it has held since 2013; it will pass Eris in distance by about 2045.[^astdys][^horizons] The explorer draws the present osculating orbit from JPL elements, so its perihelion near Neptune's orbit and its long outward swing are real; the body is enlarged for visibility.[^sbdb] ### Brightness Gonggong's absolute magnitude, measured in the "TNOs are Cool" programme, is about 2.34, which ranks it among the ten intrinsically brightest trans-Neptunian objects; the Minor Planet Center and JPL adopt a brighter value, near 1.8.[^boehnhardt2014][^sbdb] At its present distance of almost 90 AU it appears much fainter than [[Eris_(dwarf_planet)|Eris]], which is farther away but reflects a far larger fraction of the light it receives.[^santos2012][^sicardy2011] ## Physical characteristics ### Surface and spectra Gonggong reflects about 14 percent of the visible light that falls on it.[^kiss2019] Its first near-infrared [[Spectroscopy|spectrum]], taken in 2011 with the FIRE spectrograph on the Magellan Baade telescope in Chile, showed a strongly red slope and broad absorption bands near 1.5 and 2 μm; Hubble Space Telescope photometry confirmed the 1.5 μm band. Both are features of water ice, common on large Kuiper belt objects.[^brown2011][^brown2012] Gonggong is among the reddest known trans-Neptunian objects, which is unusual for a body with so much water ice. Brown and colleagues suggested that methane, too faint to detect in their data, is present and has been converted by sunlight and cosmic rays into reddish organic residues, tholins.[^brown2011][^boehnhardt2014] Spectra from 2015 showed a band at 2.27 μm attributed to methanol and its radiation products.[^holler2017] JWST spectra from 2022 found ethane ice, though less than on Sedna, small amounts of [[Carbon|carbon]] dioxide bound to dark material or ices, and complex organics, but no methane or methanol, contrary to the earlier reports.[^emery2024] The presence of water ice has been read as a sign of a brief episode of cryovolcanism long ago.[^brown2011blog3] ### Possible atmosphere Gonggong is massive enough to hold traces of volatile methane even at perihelion, where it is warmer than [[Quaoar]], so a thin methane atmosphere is possible; Brown ranks it, like Quaoar, near the size limit for keeping volatile ices.[^brown2011][^brown2012] Johnson and colleagues modelled volatile loss from Kuiper belt objects: [[Nitrogen|nitrogen]], more volatile, should have escaped almost entirely, leaving only traces, while methane may survive, condensing on the surface near aphelion where radiation slowly darkens it.[^johnson2015] Soon after Gonggong formed, a more substantial atmosphere, fed by cryovolcanism, may have existed and then escaped over time.[^brown2011blog3][^johnson2015] ### Size | Year | Diameter (km) | Method | Source | |---|---|---|---| | 2010 | 1,752 | estimate from brightness | Tancredi[^tancredi2010] | | 2011 | 1,000–1,500 | best-fit albedo | Brown et al.[^brown2011] | | 2012 | 1,280 | thermal (Herschel) | Santos-Sanz et al.[^santos2012] | | 2013 | 1,142 | thermal (Herschel and Spitzer) | Lellouch et al.[^lellouch2013] | | 2016 | 1,535 | thermal and K2 light curve | Pál et al.[^pal2016] | | 2019 | 1,230 ± 50 | thermal, mass and density | Kiss et al.[^kiss2019] | Gonggong is too distant to resolve, so its size must be inferred from its brightness and thermal emission. Early estimates scattered widely. In 2016 Pál and colleagues combined Kepler K2 photometry with Herschel data and, assuming an equator-on view and a dark surface with an albedo of 0.089, found a diameter of 1,535 km, which would have made it larger than [[Makemake]].[^pal2016] Kiss and colleagues then showed in 2019, from the orbit of its moon, that the system is seen almost pole-on, and revised the diameter to about 1,230 km, making Gonggong the fifth-largest known [[Trans-Neptunian_object|trans-Neptunian object]] after [[Pluto]], Eris, Haumea and Makemake.[^kiss2019] Several astronomers consider it a dwarf planet. Sheppard and colleagues noted that even at an albedo of 1 it could not be smaller than about 580 km, above the size at which cold icy bodies were then expected to become round.[^sheppard2011] [[Saturn]]'s moon Iapetus, however, is out of equilibrium at 1,470 km, so roundness is likely but not certain.[^castillo2007] ### Mass, density and rotation From the orbit of Xiangliu, Kiss and colleagues derived a system mass of 1.75 × 10²¹ kg and, with the 1,230 km diameter, a [[Density|density]] of about 1.74 g/cm³; the 2016 size would have implied an implausible 0.92 g/cm³.[^kiss2019] Gonggong is therefore slightly more massive and denser than [[Charon_(moon)|Charon]], whose mass is 1.586 × 10²¹ kg and density 1.70 g/cm³, and the fifth most massive known trans-Neptunian object.[^kiss2019][^fs-pluto] At that size and density it should be in hydrostatic equilibrium, as a slightly flattened Maclaurin spheroid.[^kiss2019] Kepler observations in March 2016 found a light-curve amplitude of only about 0.09 magnitudes, consistent with a pole-on view, and two possible rotation periods, 44.81 or 22.4 hours; Kiss and colleagues favour 22.4 hours.[^pal2016][^kiss2019] That is slow for a trans-Neptunian object, most of which rotate in 6–12 hours, and implies a flattening of only about 0.03.[^kiss2019] ## Satellite The slow rotation found in 2016 suggested that a moon might have braked Gonggong's spin through [[Tide|tides]], as Charon has braked [[Pluto]]'s.[^lakdawalla2016] Csaba Kiss and colleagues searched archival Hubble Space Telescope images and found a faint satellite in images taken on 18 September 2010, at least 15,000 km from Gonggong; the discovery was announced at the Division for Planetary Sciences meeting on 17 October 2016 and published in 2017.[^marton2016][^kiss2017] The moon is roughly 100 km across and orbits in about 25 days.[^kiss2017][^kiss2019] Further Hubble images allowed Kiss and colleagues to fit the moon's orbit in 2019. Through [[Kepler's_laws_of_planetary_motion|Kepler's third law]] the orbit gave the system's mass, and its orientation, seen from Earth at a steep angle, showed that Gonggong's pole points nearly towards the observer, which explained the small light-curve amplitude and brought the diameter estimate down.[^kiss2019] The moon was named Xiangliu on 5 February 2020, together with Gonggong, after the nine-headed poisonous serpent who serves Gonggong in Chinese mythology and shares his destructive floods.[^mpc][^mpc121135] ## Exploration No spacecraft has visited Gonggong, and none is planned. Its distance makes it one of the hardest large bodies to reach: at 89 AU, light takes about 12 hours to arrive from the Sun, while [[NASA]]'s New Horizons, one of the fastest spacecraft ever launched, needed 3,462 days, about nine and a half years, to reach Pluto, less than half as far out (derived).[^astdys][^jhuapl2016] Amanda Zangari and colleagues calculated that a flyby would take at least 20 years with current rockets; with a [[Jupiter]] gravity assist and a launch in 2030 or 2031, a spacecraft could arrive in just under 25 years, when Gonggong would be about 95 AU from the Sun.[^zangari2019] Until such a mission flies, Gonggong, like most large bodies of the outer [[Kuiper_belt|Kuiper belt]] and scattered disc, is studied only remotely: its composition comes from ground-based and space telescopes, most recently JWST, and its size, mass and spin from thermal measurements, photometry and the orbit of its moon.[^emery2024][^kiss2019] ## See also - [[Dwarf_planet]] · [[Scattered_disc]] · [[Trans-Neptunian_object]] - [[Eris_(dwarf_planet)]] · [[Sedna_(dwarf_planet)]] - [[Charon_(moon)]] · [[Quaoar]] - [[Resonant_trans-Neptunian_object]] - [[PORTAL_Solar_System|Solar System portal]] ## Notes Derived numbers are computed from the cited values: the orbital period from the JPL value of about 200,000 days, ≈ 548 years, which at 100 years/s gives a lap of about 5.5 seconds; the 3:10 check, 3 × 548 ≈ 1,644 years against 10 × 164.8 ≈ 1,648 years for Neptune; the light time at 89 AU, 89 × 499 s ≈ 44,400 s ≈ 12.3 hours; and New Horizons' travel time, 3,462 days ≈ 9.5 years. ## References [^sbdb]: JPL Small-Body Database, "225088 Gonggong (2007 OR10)" (orbital elements and absolute magnitude fetched 2026-09-18). https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=225088 [^horizons]: JPL Solar System Dynamics. "Horizons" ephemerides for 225088 Gonggong (perihelion 1857; heliocentric distance and radial velocity). https://ssd.jpl.nasa.gov/horizons/ [^astdys]: AstDyS. "Asteroids — Dynamic Site", heliocentric distances of distant objects (2021). https://newton.spacedys.com/astdys/ [^fs-pluto]: Williams, D. R. "Pluto Fact Sheet" (includes Charon). NASA NSSDCA, last updated 11 January 2024. https://nssdc.gsfc.nasa.gov/planetary/factsheet/plutofact.html [^mpc]: Minor Planet Center. "(225088) Gonggong = 2007 OR10". https://www.minorplanetcenter.net/db_search/show_object?object_id=225088 [^mpec2009]: Minor Planet Center (7 January 2009). "MPEC 2009-A42: 2007 OR10". https://minorplanetcenter.net/mpec/K09/K09A42.html [^mpc121135]: Minor Planet Center (5 February 2020). "M.P.C. 121135". https://minorplanetcenter.net/iau/ECS/MPCArchive/2020/MPC_20200205.pdf [^buie2019]: Buie, M. W. (24 May 2019). "Orbit fit and astrometric record for 225088". Southwest Research Institute. https://www.boulder.swri.edu/~buie/kbo/astrom/225088.html [^grundy2020]: Grundy, W. (13 February 2020). "Gonggong (225088 2007 OR10)". Lowell Observatory. http://www2.lowell.edu/users/grundy/tnbs/225088_2007_OR10_Gonggong.html [^lowe]: Lowe, A. "(225088) 2007 OR10 precovery images". https://andrew-lowe.ca/2007or10.htm [^schwamb2009]: Schwamb, M. E.; Brown, M. E.; Rabinowitz, D. L. (2009). "A search for distant Solar System bodies in the region of Sedna". *The Astrophysical Journal Letters* 694: L45–L48. https://doi.org/10.1088/0004-637X/694/1/L45 [^schwamb2010]: Schwamb, M. E.; Brown, M. E.; Rabinowitz, D. L.; Ragozzine, D. (2010). "Properties of the distant Kuiper belt: Results from the Palomar Distant Solar System Survey". *The Astrophysical Journal* 720: 1691–1707. https://doi.org/10.1088/0004-637X/720/2/1691 [^schwamb2019a]: Schwamb, M. (9 April 2019). "2007 OR10 needs a name!". The Planetary Society. http://www.planetary.org/blogs/guest-blogs/2019/or10-needs-a-name.html [^schwamb2019b]: Schwamb, M. (29 May 2019). "The people have voted on 2007 OR10's future name!". The Planetary Society. http://www.planetary.org/blogs/guest-blogs/2019/or10-vote-results.html [^sciencedaily2011]: ScienceDaily (22 August 2011). "Astronomers find ice and possibly methane on Snow White, a distant dwarf planet". https://www.sciencedaily.com/releases/2011/08/110822124955.htm [^brown2009blog]: Brown, M. E. (10 March 2009). "Snow White needs a bailout". *Mike Brown's Planets*. http://www.mikebrownsplanets.com/2009/03/snow-white-needs-bailout.html [^brown2011blog]: Brown, M. E. (9 August 2011). "The redemption of Snow White (part 1)". *Mike Brown's Planets*. http://www.mikebrownsplanets.com/2011/08/redemption-of-snow-white-part-1.html [^brown2011blog3]: Brown, M. E. (20 August 2011). "The redemption of Snow White (part 3 of 3)". *Mike Brown's Planets*. http://www.mikebrownsplanets.com/2011/08/redemption-of-snow-white-part-3-of-3.html [^jpl2016]: Dyches, P. (11 May 2016). "2007 OR10: Largest unnamed world in the Solar System". NASA Jet Propulsion Laboratory. http://www.jpl.nasa.gov/news/news.php?feature=6509 [^iau2019]: International Astronomical Union (10 April 2019). "Astronomers invite the public to help name Kuiper belt object". Announcement ann19021. https://www.iau.org/news/announcements/detail/ann19021/ [^unicode2022]: Anderson, D. (4 May 2022). "Out of this world: New astronomy symbols approved for the Unicode Standard". Unicode blog. http://blog.unicode.org/2022/05/out-of-this-world-new-astronomy-symbols.html [^boehnhardt2014]: Boehnhardt, H.; Schulz, D.; Protopapa, S.; Götz, C. (2014). "Photometry of transneptunian objects for the Herschel key program 'TNOs are Cool'". *Earth, Moon, and Planets* 114: 35–57. https://doi.org/10.1007/s11038-014-9450-x [^santos2012]: Santos-Sanz, P.; Lellouch, E.; Fornasier, S.; et al. (2012). "'TNOs are cool': A survey of the trans-Neptunian region. IV. Size/albedo characterization of 15 scattered disk and detached objects observed with Herschel-PACS". *Astronomy & Astrophysics* 541: A92. https://doi.org/10.1051/0004-6361/201118541 [^sicardy2011]: Sicardy, B.; Ortiz, J. L.; Assafin, M.; et al. (2011). "A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation". *Nature* 478: 493–496. https://doi.org/10.1038/nature10550 [^kiss2019]: Kiss, C.; Marton, G.; Parker, A. H.; et al. (2019). "The mass and density of the dwarf planet (225088) 2007 OR10". *Icarus* 334: 3–10. https://doi.org/10.1016/j.icarus.2019.03.013 [^brown2011]: Brown, M. E.; Burgasser, A. J.; Fraser, W. C. (2011). "The surface composition of large Kuiper belt object 2007 OR10". *The Astrophysical Journal Letters* 738: L26. https://doi.org/10.1088/2041-8205/738/2/L26 [^brown2012]: Brown, M. E. (2012). "The compositions of Kuiper belt objects". *Annual Review of Earth and Planetary Sciences* 40: 467–494. https://doi.org/10.1146/annurev-earth-042711-105352 [^holler2017]: Holler, B. J.; Young, L. A.; Bus, S. J.; Protopapa, S. (2017). "Methanol ice on Kuiper belt objects 2007 OR10 and Salacia: Implications for formation and dynamical evolution". *European Planetary Science Congress* 11, EPSC2017-330. https://meetingorganizer.copernicus.org/EPSC2017/EPSC2017-330.pdf [^emery2024]: Emery, J. P.; Wong, I.; Brunetto, R.; et al. (2024). "A tale of 3 dwarf planets: Ices and organics on Sedna, Gonggong, and Quaoar from JWST spectroscopy". *Icarus* 414: 116017. https://doi.org/10.1016/j.icarus.2024.116017 [^johnson2015]: Johnson, R. E.; Oza, A.; Young, L. A.; Volkov, A. N.; Schmidt, C. (2015). "Volatile loss and classification of Kuiper belt objects". *The Astrophysical Journal* 809: 43. https://doi.org/10.1088/0004-637X/809/1/43 [^tancredi2010]: Tancredi, G. (2010). "Physical and dynamical characteristics of icy 'dwarf planets' (plutoids)". *Proceedings of the International Astronomical Union* 5 (S263): 173–185. https://doi.org/10.1017/S1743921310001717 [^lellouch2013]: Lellouch, E.; Santos-Sanz, P.; Lacerda, P.; et al. (2013). "'TNOs are cool': A survey of the trans-Neptunian region. IX. Thermal properties of Kuiper belt objects and Centaurs from combined Herschel and Spitzer observations". *Astronomy & Astrophysics* 557: A60. https://doi.org/10.1051/0004-6361/201322047 [^pal2016]: Pál, A.; Kiss, C.; Müller, T. G.; et al. (2016). "Large size and slow rotation of the trans-Neptunian object (225088) 2007 OR10 discovered from Herschel and K2 observations". *The Astronomical Journal* 151: 117. https://doi.org/10.3847/0004-6256/151/5/117 [^sheppard2011]: Sheppard, S. S.; Udalski, A.; Trujillo, C.; et al. (2011). "A southern sky and galactic plane survey for bright Kuiper belt objects". *The Astronomical Journal* 142: 98. https://doi.org/10.1088/0004-6256/142/4/98 [^castillo2007]: Castillo-Rogez, J. C.; Matson, D. L.; Sotin, C.; et al. (2007). "Iapetus' geophysics: Rotation rate, shape, and equatorial ridge". *Icarus* 190: 179–202. https://doi.org/10.1016/j.icarus.2007.02.018 [^lakdawalla2016]: Lakdawalla, E. (19 October 2016). "DPS/EPSC update: 2007 OR10 has a moon!". The Planetary Society. http://www.planetary.org/blogs/emily-lakdawalla/2016/10190940-dpsepsc-update-2007-or10.html [^marton2016]: Marton, G.; Kiss, C.; Müller, T. G. (2016). Abstract in *DPS/EPSC 2016 Abstract Book*, American Astronomical Society, Division for Planetary Sciences meeting 48. https://aas.org/files/dps-epsc-abstract-book-final.pdf [^kiss2017]: Kiss, C.; Marton, G.; Farkas-Takács, A.; et al. (2017). "Discovery of a satellite of the large trans-Neptunian object (225088) 2007 OR10". *The Astrophysical Journal Letters* 838: L1. https://doi.org/10.3847/2041-8213/aa6484 [^jhuapl2016]: Johns Hopkins Applied Physics Laboratory (27 October 2016). "Pluto exploration complete: New Horizons returns last bits of 2015 flyby data to Earth". http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20161027 [^zangari2019]: Zangari, A. M.; Finley, T. J.; Stern, S. A.; Tapley, M. B. (2019). "Return to the Kuiper belt: Launch opportunities from 2025 to 2040". *Journal of Spacecraft and Rockets* 56: 919–930. https://doi.org/10.2514/1.A34329 ## External links - JPL Small-Body Database: 225088 Gonggong. https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=225088 - Minor Planet Center: (225088) Gonggong. https://www.minorplanetcenter.net/db_search/show_object?object_id=225088 - Lowell Observatory: Gonggong and Xiangliu (W. Grundy). http://www2.lowell.edu/users/grundy/tnbs/225088_2007_OR10_Gonggong.html - Precovery images of 2007 OR10 (A. Lowe). https://andrew-lowe.ca/2007or10.htm ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Gonggong_(dwarf_planet)) : [Wikitube](https://en.wikitube.io/wiki/Gonggong_(dwarf_planet)) · pinned revision [1373550743](https://en.wikipedia.org/w/index.php?oldid=1373550743) · 2026-09-18 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Solar_System]]. --- *Solar System portal child articles, wave 1 · 2026-09-18 · drafted · row SOL-075 · explorer state `?obj=Gonggong`.*