List of exomoon candidates

Short description: None

As of 2026[update], there have been no positive confirmations of satellites of extra-solar planets (exomoons); however, some evidence in favour of their existence has been produced.

## Contents

* 1 Timeline
* 2 Table
* 3 See also
* 4 References

## Timeline

This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by expanding it with reliably sourced entries.

* 2012 — It has been surmised that J1407b, a possibly planetary-mass object that eclipsed the star V1400 Centauri (aka. J1407) in 2007, may have a few moons based on gaps observed in its circumstellar disk or ring system.[1] Later studies have since found that J1407b is most likely a free-floating sub-brown dwarf or rogue planet, possibly less than 6 Jupiter masses.[2]
* 2012 — The confirmed hot Jupiter planet WASP-12b may also possess a moon.[3]
* December 2013, April 2014 — A candidate exomoon of a free-floating planet MOA-2011-BLG-262L, was announced, but due to degeneracies in the modelling of the microlensing event, the observations can also be explained as a Neptune-mass planet orbiting a low-mass red dwarf, a scenario the authors consider to be more likely.[4][5][6] In 2024 the latter scenario was confirmed.[7]
* October 2018 — researchers using the Hubble Space Telescope published observations of the candidate exomoon Kepler-1625b I, which suggest that the host planet is likely several Jupiter masses, while the exomoon may have a mass and radius similar to Neptune. The study concluded that the exomoon hypothesis is the simplest and best explanation for the available observations, though warned that it is difficult to assign a precise probability to its existence and nature.[8][9]
* April 2019 — reanalysis concluded that the data was fit better by a planet-only model. According to this study, the discrepancy was an artifact of the data reduction, and Kepler-1625b I likely does not exist.[10]
* September 2019 – A hypothesis involving potential transits of large exomoons being detached from their planets (see ploonet) was posited to explain the light flux-variations of the Tabby's Star, which were identified from the data collected by Kepler space telescope.[11]
* August 2020 — A paper by Chris Fox and Paul Wiegert examined the Kepler dataset for indications of exomoons solely from transit timing variations. Eight candidate signals were found that were consistent with an exomoon, however the signals could also be explained by the presence of another planet. Fox and Wiegert's conclusion was more and higher quality transit timing data would be required to establish whether these are truly moons or not.[12] David Kipping re-derived the timings of six of the eight targets (based on a pre-peer review version) and evaluated the TTV evidence as uncompelling. The same study finds that Kepler-1625b I remains an exomoon candidate.[13]
* August 2021 — astronomers reported an habitable-zone 1.7 R⊕ exomoon candidate transiting one of the components in the planetary-mass binary 2MASS J1119-1137AB.[14]
* January 2022 — an exomoon candidate was reported around the planet Kepler-1708b, and because it is orbiting a planet at approximately 1.6 AU from a star that is slightly more luminous than the Sun, it too could be within the habitable zone.[15] However, this candidate is based on limited observations (only two transits) and some consider the data to be non-convincing.[16]
* November 2022 — another exomoon candidate was reported around the planet Kepler-1513b (KOI-3678.01). Unlike the previous giant exomoon candidates of Kepler-1625 and Kepler-1708, this exomoon would be terrestrial-mass, ranging from 0.76 Lunar masses to 0.34 Earth masses depending on the planet's mass and moon's orbital period.[17]
* October 2023 — a follow-up study by the same team found that the observed TTVs are caused by a second planet in the system, and not by a moon.[18]
* December 2023 — The exomoon candidate around Kepler-1625b was again challenged, along with the Kepler-1708b candidate. This study argues that the statistical significance of these exomoon candidates is lower than previously claimed (with false positive probabilities of 10.9% and 1.6%, respectively) and that true giant exomoons would have stronger evidence. Evidence for exomoon transits may be caused by stellar activity in the Kepler light curves.[19] Kipping's team published a response arguing that these exomoon candidates remain possible.[20]
* October 2024 — New measurements with the Very Large Telescope of the star WASP-49 gave more evidences favoring the presence of a possible volcanically active-moon around the hot Jupiter WASP-49b.[21]
* A similar study in 2025 with JWST suggested that the sulfur dioxide detection in the atmosphere of WASP-39b is due to the presence of a volcanically active-exomoon. [22]
* 2025 — While investigating HD 206893 B with the GRAVITY instrument at the Very Large Telescope (VLT), signs of a potential very massive exomoon was detected around HD 206893 B. If confirmed, the exomoon's mass should be 40% of Jupiter's mass.[23][24]

## Table

Possible Neptune-sized exomoon or double planet, indicated by transit observations.[32][9] Host star
of the
host planet(s)  | Planet designation  | Planet mass  | Planet
semimajor
axis (AU)  | Exomoon
semimajor
axis  | Exomoon
mass (M⊕)  | Notes

|
|
|
|
|
|

N/A  | J1407b | 06 <6

|♃|J}}}}}}[2]

| N/A  | 0.396–0.421 AU  | <0.8  | One possible exomoon residing in a 4 million km-wide gap in J1407b's circumplanetary disk.[25] Other ring gaps in J1407b's disk may also contain exomoons.
N/A  | 2MASS J1119-1137A or B | 3.7 [[Astronomy:Jupiter mass | J}}}}}}]]  | 3.6 ± 0.9
separation from each other | 0.004 - 0.009 AU  | 0.5 - 1  | Found using the transit method. A habitable-zone exomoon candidate transiting a directly imaged free-floating planet or isolated planetary-mass object.[14]
N/A  | 2MASS J2117-2940  | 7 [[Astronomy:Jupiter mass | J}}}}}}]]  | N/A  | 0.005 AU  | ~0.5  | Candidate exomoon transit detected in Spitzer observations of 2MASS J21171431-2940034.[26]
HD 189733 | HD 189733 b | 1.13 [[Astronomy:Jupiter mass | J}}}}}}]] | 0.031 | 0.0087 AU | ? | Found by studying periodic increases and decreases in light given off from HD 189733 b. Outside of planet's Hill sphere.[27]
<0.00112 AU | ~ 0.015 | Exo-Io candidate;[28] The sodium and potassium data[29][30] at HD 189733b is consistent with evaporating exomoons and/or their corresponding gas torus.[31]
Kepler-409 | Kepler-409b | 1.00 M⊕ | 0.320 | 0.222 RHill | 0.300 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
Kepler-517 | Kepler-517b | 7.59 M⊕ | 0.298 | 0.278 RHill | 0.499 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
Kepler-809 | Kepler-809b | 38.02 M⊕ | 0.308 | 0.289 RHill | 2.931 | Possible exomoon from transit timing variations.[12]
Kepler-857 | Kepler-857b | 14.13 M⊕ | 0.376 | 0.208 RHill | 1.636 | Possible exomoon from transit timing variations.[12]
Kepler-1000 | Kepler-1000b | 19.95 M⊕ | 0.534 | 0.235 RHill | 1.551 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
Kepler-1326 | Kepler-1326b | 24.55 M⊕ | 0.2691 | 0.295 RHill | 6.057 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
Kepler-1442 | Kepler-1442b | 14.13 M⊕ | 0.405 | 0.208 RHill | 1.586 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
Kepler-1708 | Kepler-1708b | 4.6 <4.6

|♃|J}}}}}} || 1.64 || 0.005 AU
(11.7 RP) || 37 <37

| Name: Kepler-1708b

Possible Neptune-sized exomoon or double planet, indicated by transit observations.[15]

KOI-868 | KOI-868.01 | 0.689 [[Astronomy:Jupiter mass | J}}}}}}]]  | 0.6534  | 0.0221 AU  | 0.31  | Possible exomoon from transit timing variations.[33] Potentially habitable exomoon with a radius of 1.23 R⊕.[34]
KOI-268 | KOI-268.01 | 9.33 M⊕ | 0.47 | 0.217 RHill | 0.817 | Possible exomoon from transit timing variations,[12] since deemed unlikely.[13]
WASP-12 | WASP-12b[35] | 1.465 [[Astronomy:Jupiter mass | J}}}}}}]]  | 0.0232  |  | 03.485 6.4

(radius)[36]

6 RP |  | Found by studying periodic increases and decreases in light given off from WASP-12b. Outside of planet's Hill sphere.[27]
WASP-39 | WASP-39b | 0.275 MJ | 0.0486  | –  | ~ 0.015  | [22]
WASP-49 | WASP-49b | 0.37 [[Astronomy:Jupiter mass | J}}}}}}]] | 0.0379 | < 1.74 RP | ~ 0.015 | Exo-Io candidate; The sodium exosphere around WASP-49b could be due to a volcanically active Io-like exomoon.[28][21]
WASP-76 | WASP-76b | 0.92 [[Astronomy:Jupiter mass | J}}}}}}]] | 0.033 | 1.125 RP | ~ 0.015 | Exo-Io candidate; Sodium detected via absorption spectroscopy around WASP-76b[37] is consistent with an extrasolar toroidal atmosphere[38] generated by an evaporating exomoon.[31]
WASP-121 | WASP-121b | 1.184 [[Astronomy:Jupiter mass | J}}}}}}]] | 0.02544 | ~ 1.9 RP | ~ 0.015 | Exo-Io candidate; The sodium detected via absorption spectroscopy around WASP-121b[39] is consistent with an extrasolar gas torus possibly fueled by a hidden exo-Io.[31]
HD 206893 | HD 206893 B | 19.5+1.4
−1.3 [[Astronomy:Jupiter mass | J}}}}}}]]  | 10.75±0.08 | ~ 0.22 AU  | ~ 130  | Very large mass (around 40% of Jupiter's mass).[23][24]

## See also

* Exomoon
* Exoplanet
* Star
* Lists of stars
* Lists of exoplanets

## References

1. ↑ "Saturn-like ring system eclipses Sun-like star". https://www.sciencedaily.com/releases/2012/01/120109115830.htm.
2. ↑ 2.0 2.1 Kenworthy, M. A. et al. (January 2020). "ALMA and NACO observations towards the young exoring transit system J1407 (V1400 Cen)". Astronomy & Astrophysics 633: A115. doi:10.1051/0004-6361/201936141. Bibcode: 2020A&A...633A.115K.
3. ↑ Российские астрономы впервые открыли луну возле экзопланеты (in Russian) – "Studying of a curve of change of shine of WASP-12b has brought to the Russian astronomers unusual result: regular splashes were found out.<...> Though stains on a star surface also can cause similar changes of shine, observable splashes are very similar on duration, a profile and amplitude that testifies for benefit of exomoon existence."
4. ↑ Bennett, D.P. (2014). "A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge". The Astrophysical Journal 785 (2): 155. doi:10.1088/0004-637X/785/2/155. Bibcode: 2014ApJ...785..155B.
5. ↑ Clavin, Whitney (10 April 2014). "Faraway Moon or Faint Star? Possible Exomoon Found". NASA. http://www.jpl.nasa.gov/news/news.php?release=2014-109.
6. ↑ "First exomoon glimpsed – 1800 light years from Earth". New Scientist. https://www.newscientist.com/article/dn24773-first-exomoon-glimpsed--1800-light-years-from-earth.html.
7. ↑ Terry, Sean K.; Beaulieu, Jean-Philippe; Bennett, David P.; Bhattacharya, Aparna; Hulberg, Jon; Huston, Macy J.; Koshimoto, Naoki; Blackman, Joshua W. et al. (2025). "A Candidate High-velocity Exoplanet System in the Galactic Bulge". The Astronomical Journal 169 (3): 131. doi:10.3847/1538-3881/ad9b0f. Bibcode: 2025AJ....169..131T.
8. ↑ Teachey, Alex et al. (2017). "HEK VI: On the Dearth of Galilean Analogs in Kepler and the Exomoon Candidate Kepler-1625b I". The Astronomical Journal 155 (1): 36. doi:10.3847/1538-3881/aa93f2. Bibcode: 2018AJ....155...36T.
9. ↑ 9.0 9.1 Teachey, Alex; Kipping, David M. (4 October 2018). "Evidence for a large exomoon orbiting Kepler-1625b". Science Advances 4 (10). doi:10.1126/sciadv.aav1784. PMID 30306135. Bibcode: 2018SciA....4.1784T.
10. ↑ Laura Kreidberg; Rodrigo Luger; Megan Bedell (24 April 2019). "No Evidence for Lunar Transit in New Analysis of HST Observations of the Kepler-1625 System". The Astrophysical Journal 877 (2). doi:10.3847/2041-8213/ab20c8. Bibcode: 2019ApJ...877L..15K.
11. ↑ Sucerquia, Mario et al. (October 2019). "Ploonets: formation, evolution, and detectability of tidally detached exomoons". Monthly Notices of the Royal Astronomical Society 489 (2): 2313–2322. doi:10.1093/mnras/stz2110. Bibcode: 2019MNRAS.489.2313S.
12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 Fox, Chris; Wiegert, Paul (23 November 2020). "Exomoon Candidates from Transit Timing Variations: Eight Kepler systems with TTVs explainable by photometrically unseen exomoons". Monthly Notices of the Royal Astronomical Society 501 (2): 2378–2393. doi:10.1093/mnras/staa3743. Bibcode: 2021MNRAS.501.2378F.
13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 13.6 Kipping, David (8 August 2020). "An Independent Analysis of the Six Recently Claimed Exomoon Candidates". The Astrophysical Journal 900 (2): L44. doi:10.3847/2041-8213/abafa9. Bibcode: 2020ApJ...900L..44K.
14. ↑ 14.0 14.1 Limbach, Mary Anne; Vos, Johanna M.; Winn, Joshua N.; Heller, Rene; Mason, Jeffrey C.; Schneider, Adam C.; Dai, Fei (2021-08-18). "On the Detection of Exomoons Transiting Isolated Planetary-mass Objects" (in en). The Astrophysical Journal Letters 918 (2): L25. doi:10.3847/2041-8213/ac1e2d. Bibcode: 2021ApJ...918L..25L.
15. ↑ 15.0 15.1 Kipping, David et al. (13 January 2022). "An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i". Nature 6 (3): 367–380. doi:10.1038/s41550-021-01539-1. PMID 35399159. Bibcode: 2022NatAs...6..367K.
16. ↑ "Astronomers may have found a huge moon around a Jupiter-like exoplanet". https://www.newscientist.com/article/2304546-astronomers-may-have-found-a-huge-moon-around-a-jupiter-like-exoplanet/.
17. ↑ Kipping, David; Yahalomi, Daniel A. (January 2023). "A search for transit timing variations within the exomoon corridor using Kepler data". Monthly Notices of the Royal Astronomical Society 518 (3): 3482–3493. doi:10.1093/mnras/stac3360. Bibcode: 2023MNRAS.518.3482K.
18. ↑ Yahalomi, Daniel A. et al. (January 2024). "Not So Fast Kepler-1513: A Perturbing Planetary Interloper in the Exomoon Corridor". Monthly Notices of the Royal Astronomical Society 527 (1): 620–639. doi:10.1093/mnras/stad3070. Bibcode: 2024MNRAS.527..620Y.
19. ↑ Heller, René; Hippke, Michael (December 2023). "Large exomoons unlikely around Kepler-1625 b and Kepler-1708 b". Nature Astronomy 8 (2): 193–206. doi:10.1038/s41550-023-02148-w. Bibcode: 2024NatAs...8..193H.
20. ↑ Kipping, David; Teachey, Alex (January 2024). "A Reply to: Large Exomoons unlikely around Kepler-1625 b and Kepler-1708 b". Nature Astronomy.
21. ↑ 21.0 21.1 Oza, Apurva V.; Seidel, Julia V.; Hoeijmakers, H. Jens; Unni, Athira; Kesseli, Aurora Y.; Schmidt, Carl A.; Sivarani, Thirupathi; Bello-Arufe, Aaron et al. (2024-10-01). "Redshifted Sodium Transient near Exoplanet Transit". The Astrophysical Journal Letters 973 (2): L53. doi:10.3847/2041-8213/ad6b29. ISSN 2041-8205. Bibcode: 2024ApJ...973L..53O.
22. ↑ 22.0 22.1 Oza, Apurva V.; Gebek, Andrea; Moritz Meyer zu Westram; Tokadjian, Armen; Piro, Anthony L.; Hu, Renyu; Unni, Athira; Chari, Raghav; Bello-Arufe, Aaron; Schmidt, Carl A.; Louca, Amy J.; Miguel, Yamila; Estrela, Raissa; Yang, Jeehyun; Damiano, Mario; Hasegawa, Yasuhiro; Welbanks, Luis; Powell, Diana; Garg, Rishabh; Gupta, Pulkit; Yung, Yuk L.; Lopes, Rosaly M. C. (2025). "Volcanic Satellites Tidally Venting Na, K, SO2 in Optical & Infrared Light". arXiv:2509.08349 [astro-ph.EP].
23. ↑ 23.0 23.1 Kral, Q.; Wang, J.; Kammerer, J.; Lacour, S.; Malin, M.; Winterhalder, T.; Charnay, B.; Perrot, C. et al. (2025-11-25), Exomoon search with VLTI/GRAVITY around the substellar companion HD 206893 B, http://arxiv.org/abs/2511.20091, retrieved 2026-01-22
24. ↑ 24.0 24.1 "Wobbling exoplanet hints at a hidden exomoon so massive it could redefine the word 'moon' altogether" (in en). 2026-01-22. https://www.space.com/astronomy/exoplanets/wobbling-exoplanet-hints-at-a-hidden-exomoon-so-massive-it-could-redefine-the-word-moon-altogether.
25. ↑ Matthew A. Kenworthy, Eric E. Mamajek (2015). "Modeling giant extrasolar ring systems in eclipse and the case of J1407b: sculpting by exomoons?". The Astrophysical Journal 800 (2): 126. doi:10.1088/0004-637X/800/2/126. Bibcode: 2015ApJ...800..126K.
26. ↑ Limbach, Mary Anne; Vos, Johanna M.; Vanderburg, Andrew; Dai, Fei (2024-05-13). "Occurrence Rates of Exosatellites Orbiting 3-30M$_{\rm Jup}$ Hosts from 44 Spitzer Light Curves". arXiv:2405.08116 [astro-ph.EP].
27. ↑ 27.0 27.1 Ben-Jaffel, Lotfi; Ballester, Gilda (3 April 2014). "Transit of Exomoon Plasma Tori: New Diagnosis". The Astrophysical Journal 785 (2): L30. doi:10.1088/2041-8205/785/2/L30. Bibcode: 2014ApJ...785L..30B.
28. ↑ 28.0 28.1 Oza, Apurva V.; Johnson, Robert E.; Lellouch, Emmanuel; Schmidt, Carl; Schneider, Nick; Huang, Chenliang; Gamborino, Diana; Gebek, Andrea et al. (2019-08-28). "Sodium and Potassium Signatures of Volcanic Satellites Orbiting Close-in Gas Giant Exoplanets". The Astrophysical Journal 885 (2): 168. doi:10.3847/1538-4357/ab40cc. Bibcode: 2019ApJ...885..168O.
29. ↑ Wyttenbach, A.; Ehrenreich, D.; Lovis, C.; Udry, S.; Pepe, F. (5 May 2015). "Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph". Astronomy & Astrophysics 577: A62. doi:10.1051/0004-6361/201525729. Bibcode: 2015A&A...577A..62W. https://www.aanda.org/articles/aa/full_html/2015/05/aa25729-15/aa25729-15.html.
30. ↑ Keles, Engin; Mallonn, Matthias; von Essen, Carolina; Carroll, Thorsten; Alexoudi, Xanthippi; Pino, Lorenzo; Ilyin, Ilya; Poppenhager, Katja et al. (October 2019). "The potassium absorption on HD189733b and HD209458b". Monthly Notices of the Royal Astronomical Society: Letters 489 (1): L37-L41. doi:10.1093/mnrasl/slz123. Bibcode: 2019MNRAS.489L..37K.
31. ↑ 31.0 31.1 31.2 Gebek, Andrea; Oza, Apurva (29 July 2020). "Alkaline exospheres of exoplanet systems: evaporative transmission spectra". Monthly Notices of the Royal Astronomical Society 497 (4): 5271–5291. doi:10.1093/mnras/staa2193. Bibcode: 2020MNRAS.497.5271G. https://academic.oup.com/mnras/article-abstract/497/4/5271/5877918?redirectedFrom=fulltext. Retrieved 8 December 2020.
32. ↑ Drake, Nadia (3 October 2018). "Weird giant may be the first known alien moon – Evidence is mounting that a world the size of Neptune could be orbiting a giant planet far, far away.". National Geographic Society. https://www.nationalgeographic.com/science/2018/10/news-first-exomoon-nasa-kepler-planets-facts-space/.
33. ↑ Kipping, David (2015). "The Hunt for Exomoons with Kepler (HEK): V. A Survey of 41 Planetary Candidates for Exomoons". NASA ADS. https://ui.adsabs.harvard.edu/abs/2015ApJ...813...14K/abstract. Retrieved 2026-02-21.
34. ↑ Guimarães, Ana (2018). "The Best Planets to Harbor Detectable Exomoons". NASA ADS. https://ui.adsabs.harvard.edu/abs/2018AJ....156...50G/abstract. Retrieved 2026-02-21.
35. ↑ "WASP-12 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/wasp_12_b--459/. Retrieved 1 February 2015.
36. ↑ Российские астрономы впервые открыли луну возле экзопланеты (in Russian) - "Studying of a curve of change of shine of WASP-12b has brought to the Russian astronomers unusual result: regular splashes were found out.<...> Though stains on a star surface also can cause similar changes of shine, observable splashes are very similar on duration, a profile and amplitude that testifies for benefit of exomoon existence."
37. ↑ Seidel, J.V.; Ehrenreich, D.; Wyttenbach, A.; Allart, R.; Lendl, M.; Pino, L.; Bourrier, V.; Cegla, H.M. et al. (27 March 2019). "Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)★ II. A broadened sodium feature on the ultra-hot giant WASP-76b". Astronomy & Astrophysics 623: A166. doi:10.1051/0004-6361/201834776. Bibcode: 2019A&A...623A.166S.
38. ↑ Johnson, Robert E.; Huggins, Patrick (August 2006). "Toroidal Atmospheres around Extrasolar Planets". Publications of the Astronomical Society of the Pacific 118 (846): 1136–1143. doi:10.1086/506183. Bibcode: 2006PASP..118.1136J.
39. ↑ Hoeijmakers, H.J.; Seidel, J.V.; Pino, L.; Kitzmann, D.; Sindel, J.P.; Ehrenreich, D.; Oza, A.V.; Bourrier, V. et al. (18 September 2020). "Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) - IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b". Astronomy & Astrophysics 641: A123. doi:10.1051/0004-6361/202038365. Bibcode: 2020A&A...641A.123H.

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