Below is a list of the smallest exoplanets so far discovered, in terms of physical size, ordered by radius.
List[edit]
The sizes are listed in units of Earth radii (R🜨). All planets listed are smaller than Earth and Venus, up to 0.7 Earth radii. The NASA Exoplanet Archive is used as the main data source.[1][2]
| Exoplanet | Radius (R🜨) | Notes and references |
|---|---|---|
| SDSS J1228+1040 b (SDSS J122859.92+104033.0 b, WD 1226+110 b) |
0.010+0.0504 −0.0085[3][4] |
Extrasolar planetesimal. Likely a remnant iron core. Radius is in the range of 1.2 – 120 km.[3] |
| WD 1145+017 b | ~0.03[5] | Disintegrating planetesimal, likely one of several orbiting its star. Likely about one-tenth the mass of Ceres and ~200 km in radius.[5] |
| Ceres | 0.0742 | Shown for comparison |
| Pluto | 0.1863 | Shown for comparison |
| Moon | 0.2725 | Shown for comparison |
| Kepler-37b | 0.3098+0.0059 −0.0076 |
Smallest known exoplanet.[6][7] |
| PSR B1257+12 b (Draugr) | ~0.338 | Least massive known exoplanet, at 0.02 Earth masses. Radius estimated from mass-radius relationship.[8] |
| Kepler-1520b | ≲0.36 | Disintegrating planets with poorly known radii, all thought to be smaller than Mercury.[9][10] |
| KOI-2700b | ||
| K2-22b | ||
| Mercury | 0.3826 | Shown for comparison |
| Kepler-444b | 0.403+0.016 −0.014 |
[11] |
| Ganymede | 0.413 | Shown for comparison |
| Kepler-102b | 0.460±0.026 | [7] |
| Kepler-444c | 0.497+0.021 −0.017 |
[11] |
| Kepler-1971b (KOI-4777.01) | 0.51±0.03 | [12] |
| Kepler-1994b | 0.51+0.06 −0.05 |
[13] |
| Kepler-1308b | 0.52+0.06 −0.05 |
|
| Kepler-444d | 0.530+0.022 −0.019 |
[11] |
| Mars | 0.5325 | Shown for comparison |
| Kepler-62c | 0.54±0.03 | |
| Kepler-444e | 0.546+0.017 −0.015 |
[11] |
| Kepler-102c | 0.567±0.028 | [7] |
| Kepler-42d | 0.57±0.18 | |
| Kepler-1583b | 0.60+0.09 −0.05 |
|
| Kepler-1998b | 0.6+0.08 −0.04 |
[14] |
| Kepler-1087b | 0.61+0.17 −0.05 |
|
| K2-89b | 0.615±0.080 | |
| Kepler-1877b | 0.624 | |
| K2-137b | 0.64±0.10 | |
| Kepler-1371c | 0.64+0.07 −0.05 |
|
| Kepler-138b | 0.64±0.02 | [15] |
| Kepler-1130d | 0.645 | |
| Kepler-1351b | 0.65+0.05 −0.04 |
|
| Kepler-1542c | 0.65+0.09 −0.06 |
|
| Kepler-271d | 0.66±0.05 | |
| Kepler-431c | 0.668 | |
| Kepler-1558b | 0.68+0.06 −0.04 |
|
| LHS 1678 b | 0.685+0.037 −0.035 |
[16] |
| K2-116b | 0.69±0.04 | |
| Kepler-141b | 0.69±0.05 | |
| K2-297b (EPIC 201497682 b) | 0.692+0.059 −0.048 |
|
| Gliese 367 b (Tahay) | 0.699±0.024 | Smallest known exoplanet within 10 parsecs.[17] |
| Kepler-1349b | 0.700+0.630 −0.110 |
|
| Kepler-378c | 0.70±0.05 |
Excluded objects[edit]
Kepler-37e is listed with a radius of 0.37±0.18 R🜨 in the Exoplanet Archive based on KOI data, but the existence of this planet is doubtful,[18] and assuming its existence, a 2023 study found a mass of 8.1±1.7 M🜨, inconsistent with such a small radius.[19]
KOI-6705.01, listed as a potential very small planet in the KOI dataset, was shown to be a false positive in 2016.[20]
TESS candidates[edit]
Below shows a list of TESS candidates below 0.7 R🜨 that have yet to be confirmed.
| TESS object of interest | Radius (R🜨) | Notes and references |
|---|---|---|
| TOI-4307.02 | 0.57±0.14[21] | |
| TOI-486.01 | 0.59±0.03[21] |
Kepler candidates[edit]
Below shows a list of Kepler candidates below 0.7 R🜨 that have yet to be confirmed.
| Kepler object of interest | Radius (R🜨) | Notes and references |
|---|---|---|
| KOI-4582.01 | 0.35[22] | |
| KOI-2298.03 | 0.36[22] | |
| KOI-2169.04 | 0.37[22] | |
| KOI-7174.01 | 0.37[22] | |
| KOI-8012.01 | 0.42[22] | |
| KOI-6860.01 | 0.43[22] | |
| KOI-2059.02 | 0.44[22] | |
| KOI-304.02 | 0.46[22] | |
| KOI-7793.01 | 0.46[22] | |
| KOI-2678.02 | 0.48[22] | |
| KOI-6631.01 | 0.48[22] | |
| KOI-2421.02 | 0.48[22] | |
| KOI-5974.01 | 0.49[22] | |
| KOI-3444.03 | 0.5[22] | |
| KOI-2295.01 | 0.52[22] | |
| KOI-7863.01 | 0.52[22] | |
| KOI-2612.02 | 0.53[22] | |
| KOI-4657.01 | 0.54[22] | |
| KOI-8257.01 | 0.54[22] | |
| KOI-115.03 (Kepler-105d) | 0.55+0.08 −0.07 |
[23] |
| KOI-2421.01 | 0.55[22] | |
| KOI-4097.02 | 0.55[22] | |
| KOI-7645.01 | 0.55[22] | |
| KOI-3208.01 | 0.56[22] | |
| KOI-6763.01 | 0.56[22] | |
| KOI-2859.03 | 0.57[22] | |
| KOI-4146.02 | 0.57[22] | |
| KOI-2859.04 | 0.57[22] | |
| KOI-7873.01 | 0.57[22] | |
| KOI-2657.01 | 0.58[22] | |
| KOI-8277.01 | 0.58[22] | |
| KOI-4296.01 | 0.59[22] | |
| KOI-3196.01 | 0.59[22] | |
| KOI-5692.01 | 0.59[22] | |
| KOI-1964.01 | 0.6[22] | |
| KOI-4407.01 | 0.6[22] | |
| KOI-4871.01 | 0.6[22] | |
| KOI-5211.01 | 0.6[22] | |
| KOI-7888.01 | 0.6[22] | |
| KOI-3184.03 | 0.6[22] | |
| KOI-8183.01 | 0.6[22] | |
| KOI-3083.02 | 0.61[22] | |
| KOI-4421.01 | 0.61[22] | |
| KOI-4716.01 | 0.61[22] | |
| KOI-3102.01 | 0.61[22] | |
| KOI-7032.01 | 0.61[22] | |
| KOI-1843.03 | 0.61+0.12 −0.08 |
[24] |
| KOI-1499.02 | 0.62[22] | |
| KOI-605.02 | 0.62[22] | |
| KOI-7676.01 | 0.62[22] | |
| KOI-4849.01 | 0.62[22] | |
| KOI-365.02 | 0.62[22] | |
| KOI-7116.01 | 0.62[22] | |
| KOI-4421.02 | 0.62[22] | |
| KOI-7949.01 | 0.62[22] | |
| KOI-2029.04 | 0.63[22] | |
| KOI-6889.01 | 0.63[22] | |
| KOI-2636.02 | 0.63[22] | |
| KOI-3248.01 | 0.64[22] | |
| KOI-5213.01 | 0.64[22] | |
| KOI-6276.01 | 0.64[22] | |
| KOI-7617.01 | 0.64[22] | |
| KOI-7903.01 | 0.64[22] | |
| KOI-7925.01 | 0.64[22] | |
| KOI-8174.01 | 0.64[22] | |
| KOI-3083.03 | 0.65[22] | |
| KOI-4875.01 | 0.65[22] | |
| KOI-4808.01 | 0.65[22] | |
| KOI-6568.01 | 0.65[22] | |
| KOI-1619.01 | 0.66[22] | |
| KOI-3111.02 | 0.66[22] | |
| KOI-2859.05 | 0.66[22] | |
| KOI-3017.01 | 0.67[22] | |
| KOI-4907.01 | 0.67[22] | |
| KOI-1616.02 | 0.67[22] | |
| KOI-6299.01 | 0.67[22] | |
| KOI-8211.01 | 0.67[22] | |
| KOI-2593.02 | 0.68[22] | |
| KOI-4605.01 | 0.68[22] | |
| KOI-7832.01 | 0.68[22] | |
| KOI-7483.01 | 0.68[22] | |
| KOI-2623.02 | 0.68[22] | |
| KOI-7924.01 | 0.68[22] | |
| KOI-7628.01 | 0.69[22] | |
| KOI-4129.01 | 0.69[22] | |
| KOI-4822.01 | 0.69[22] | |
| KOI-6600.01 | 0.69[22] |
See also[edit]
References[edit]
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- ^ "Planetary Systems Composite Data". NASA Exoplanet Archive. Retrieved 16 July 2023.
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- ^ "Planet SDSS J1228+1040 b". Extrasolar Planets Encyclopaedia. Retrieved 2019-08-05.
- ^ a b Rappaport, S.; Gary, B. L. (June 2016). "Drifting asteroid fragments around WD 1145+017". Monthly Notices of the Royal Astronomical Society. 458 (4): 3904–3917. arXiv:1602.00740. Bibcode:2016MNRAS.458.3904R. doi:10.1093/mnras/stw612.
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- ^ a b c Bonomo, A. S.; Dumusque, X.; et al. (September 2023). "Cold Jupiters and improved masses in 38 Kepler and K2 small planet systems from 3661 HARPS-N radial velocities. No excess of cold Jupiters in small planet systems". Astronomy & Astrophysics. 677: A33. arXiv:2304.05773. Bibcode:2023A&A...677A..33B. doi:10.1051/0004-6361/202346211. S2CID 258078829.
- ^ "Exoplanet-catalog".
- ^ Ansdell, M.; Hirano, T.; Gaidos, E. (2019). "Monitoring of the D doublet of neutral sodium during transits of two 'evaporating' planets". Monthly Notices of the Royal Astronomical Society. 485 (3): 3876–3886. arXiv:1903.06217. Bibcode:2019MNRAS.485.3876G. doi:10.1093/mnras/stz693.
[...]the radii are not known but are thought to be smaller than Mercury (0.36R⊕).
- ^ Garai, Z. (2018). "Light-curve analysis of KOI 2700b: The second extrasolar planet with a comet-like tail". Astronomy & Astrophysics. 611: A63. arXiv:1712.07461. Bibcode:2018A&A...611A..63G. doi:10.1051/0004-6361/201629676. S2CID 118885868.
We confirmed the disintegrating-planet scenario of KOI 2700b.
- ^ a b c d Campante, T.; et al. (2015). "KOI-3158: The oldest known system of terrestrial-size planets". EPJ Web of Conferences. 101: 02004. arXiv:1501.07869. Bibcode:2015EPJWC.10102004C. doi:10.1051/epjconf/201510102004. S2CID 16191462.
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- ^ "Kepler-1994". NASA Exoplanet Archive. Retrieved 16 June 2023.
- ^ "Kepler-1998". NASA Exoplanet Archive. Retrieved 16 June 2023.
- ^ Piaulet, Caroline; Benneke, Björn; et al. (15 December 2022). "Evidence for the volatile-rich composition of a 1.5-Earth-radius planet". Nature Astronomy. 7: 206. arXiv:2212.08477. Bibcode:2023NatAs...7..206P. doi:10.1038/s41550-022-01835-4. S2CID 254764810.
- ^ Silverstein, Michele L.; Barclay, Thomas; et al. (February 2024). "Validation of a Third Planet in the LHS 1678 System". The Astronomical Journal. arXiv:2403.00110.
- ^ Goffo, Elisa; Gandolfi, Davide; et al. (September 2023). "Company for the ultra-high density, ultra-short period sub-Earth GJ 367 b: discovery of two additional low-mass planets at 11.5 and 34 days". The Astrophysical Journal Letters. 955 (1): L3. arXiv:2307.09181. Bibcode:2023ApJ...955L...3G. doi:10.3847/2041-8213/ace0c7.
- ^ Rajpaul, V. M.; Buchhave, L. A.; Lacedelli, G.; Rice, K.; Mortier, A.; Malavolta, L.; Aigrain, S.; Borsato, L.; Mayo, A. W.; Charbonneau, D.; Damasso, M.; Dumusque, X.; Ghedina, A.; Latham, D. W.; López-Morales, M.; Magazzù, A.; Micela, G.; Molinari, E.; Pepe, F.; Piotto, G.; Poretti, E.; Rowther, S.; Sozzetti, A.; Udry, S.; Watson, C. A. (2021), "A HARPS-N mass for the elusive Kepler-37d: A case study in disentangling stellar activity and planetary signals", Monthly Notices of the Royal Astronomical Society, 507 (2): 1847–1868, arXiv:2107.13900, Bibcode:2021MNRAS.507.1847R, doi:10.1093/mnras/stab2192
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- ^ Gaidos, Eric; Mann, Andrew W.; Ansdell, Megan (January 2016). "The Enigmatic and Ephemeral M Dwarf System KOI 6705: Cheshire Cat or Wild Goose?". The Astrophysical Journal. 817 (1): 50. arXiv:1511.06471. Bibcode:2016ApJ...817...50G. doi:10.3847/0004-637X/817/1/50.
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