List of smallest exoplanets

From Wikipedia, the free encyclopedia

Below is a list of the smallest exoplanets so far discovered, in terms of physical size, ordered by radius.

A size comparison of the planets in the Kepler-37 system and objects in the Solar System

List

This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by editing the page to add missing items, with references to reliable sources.

The sizes are listed in units of Earth radii (R🜨). All planets listed are smaller than Earth and up to 1 Earth radii. The NASA Exoplanet Archive is used as the main data source.[1][2] Radii listed in italics are estimates.

More information Exoplanet, Radius (R🜨) ...
Exoplanet Radius (R🜨) Notes and references Mass (M🜨)
SDSS J0845+2257 b 0.01-0.013 Planetesimal, enhanced in iron and silicates. [3]
WD 1145+017 b ~0.03[4] Disintegrating planetesimal, likely one of several orbiting its star. Likely about one-tenth the mass of Ceres and ~200 km in radius.[4] ~0.000016[4]
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[5]		 Smallest known exoplanet.[6][5] <0.79[5]
BD+05 4868 Ab ~0.314 Disintegrating planet, radius is just an estimate.[7] 0.02
PSR B1257+12 b (Draugr) ~0.338 Least massive known exoplanet, at 0.02 Earth masses. Radius predicted from mass-radius relationship.[8] 0.02
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-879c 0.4±0.1 [11]
Kepler-444b 0.403+0.016
−0.014		 [12]
Ganymede 0.413 Shown for comparison
Kepler-158d 0.43±0.05 [11]
Kepler-102b 0.460±0.026 [5]
Kepler-444c 0.497+0.021
−0.017		 [12]
Kepler-1971b (KOI-4777.01) 0.51±0.03 [13]
Kepler-1489c 0.51±0.08 [11]
Kepler-1994b 0.51+0.06
−0.05		 [14]
Kepler-1308b 0.52+0.06
−0.05
Kepler-444d 0.530+0.022
−0.019		 [12]
Mars 0.5325 Shown for comparison
Kepler-62c 0.54±0.03
Kepler-444e 0.546+0.017
−0.015		 [12]
Gliese 238 b 0.566±0.014 [15]
Kepler-102c 0.567±0.028 [5]
Kepler-42d 0.57±0.18
Kepler-1583b 0.60+0.09
−0.05
Kepler-1998b 0.6+0.08
−0.04		 [16]
Kepler-963c 0.6±0.2 [11]
Kepler-974c (KOI-1843.03) 0.61+0.12
−0.08		 Candidate.[17] As of 2025, the Exoplanet Archive lists it as confirmed.[2]
Kepler-1087b 0.61+0.17
−0.05
K2-89b 0.615±0.080
Kepler-1877b 0.624
Barnard's Star e ~0.637 Radius predicted from mass-radius relationship.[2] Least massive exoplanet detected by radial velocity and possibly smallest known within 10 parsecs.[18]
K2-137b 0.64±0.10[19] The discovery paper finds a larger radius of 0.89±0.09 R🜨[20]
Kepler-1371c 0.64+0.07
−0.05
Kepler-138b 0.64±0.02 [21]
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		 [22]
K2-116b 0.69±0.04
Kepler-141b 0.69±0.05
K2-297b (EPIC 201497682 b) 0.692+0.059
−0.048
Proxima Centauri d ~0.692 Radius predicted from mass-radius relationship.[2][23]
Barnard's Star d ~0.694 Radius predicted from mass-radius relationship.[2][18]
Gliese 367 b (Tahay) 0.699±0.024 [24] Smallest exoplanet within 10 parsecs with a measured radius.[24] 0.633 [24]
Kepler-2003b (KOI-4978.02) 0.7±0.1 [11]
Kepler-378c 0.70±0.05
Close

Excluded objects

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,[25] and assuming its existence, a 2023 study found a mass of 8.1±1.7 M🜨, inconsistent with such a small radius.[26]

KOI-6705.01, listed as a potential very small planet in the KOI dataset, was shown to be a false positive in 2016.[27]

Candidate planets

Below is a list of candidate planets below 0.7 R🜨. These planets have yet to be confirmed.

More information Kepler object of interest, Radius (R🜨) ...
Kepler object of interest 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[28][29]		 Extrasolar planetesimal. Likely a remnant iron core. Radius is in the range of 1.2 – 120 km.[28] Has been disputed in a 2023 publication.[30]
TRAPPIST-1i 0.228+0.025
−0.032[31]
KOI-4582.01 0.35[32]
KOI-2298.03 0.36[32]
KOI-2169.04 0.37[32]
KOI-7174.01 0.37[32]
KOI-8012.01 0.42[32]
KOI-6860.01 0.43[32]
KOI-2059.02 0.44[32]
KOI-304.02 0.46[32]
KOI-7793.01 0.46[32]
KOI-2678.02 0.48[32]
KOI-6631.01 0.48[32]
KOI-2421.02 0.48[32]
KOI-5974.01 0.49[32]
KOI-3444.03 0.5[32]
KOI-2295.01 0.52[32]
KOI-7863.01 0.52[32]
KOI-2612.02 0.53[32]
KOI-4657.01 0.54[32]
KOI-8257.01 0.54[32]
KOI-115.03 (Kepler-105d) 0.55+0.08
−0.07		 [33]
KOI-2421.01 0.55[32]
KOI-4097.02 0.55[32]
KOI-7645.01 0.55[32]
KOI-3208.01 0.56[32]
KOI-6763.01 0.56[32]
KOI-2859.03 0.57[32]
KOI-4146.02 0.57[32]
KOI-2859.04 0.57[32]
KOI-7873.01 0.57[32]
TOI-4307.02 0.57±0.14[34]
KOI-2657.01 0.58[32]
KOI-8277.01 0.58[32]
KOI-4296.01 0.59[32]
KOI-3196.01 0.59[32]
KOI-5692.01 0.59[32]
KOI-1964.01 0.6[32]
KOI-4407.01 0.6[32]
KOI-4871.01 0.6[32]
KOI-5211.01 0.6[32]
KOI-7888.01 0.6[32]
KOI-3184.03 0.6[32]
KOI-8183.01 0.6[32]
KOI-3083.02 0.61[32]
KOI-4421.01 0.61[32]
KOI-4716.01 0.61[32]
KOI-3102.01 0.61[32]
KOI-7032.01 0.61[32]
KOI-1499.02 0.62[32]
KOI-605.02 0.62[32]
KOI-7676.01 0.62[32]
KOI-4849.01 0.62[32]
KOI-365.02 0.62[32]
KOI-7116.01 0.62[32]
KOI-4421.02 0.62[32]
KOI-7949.01 0.62[32]
KOI-2029.04 0.63[32]
KOI-6889.01 0.63[32]
KOI-2636.02 0.63[32]
KOI-3248.01 0.64[32]
KOI-5213.01 0.64[32]
KOI-6276.01 0.64[32]
KOI-7617.01 0.64[32]
KOI-7903.01 0.64[32]
KOI-7925.01 0.64[32]
KOI-8174.01 0.64[32]
KOI-3083.03 0.65[32]
KOI-4875.01 0.65[32]
KOI-4808.01 0.65[32]
KOI-6568.01 0.65[32]
KOI-1619.01 0.66[32]
KOI-3111.02 0.66[32]
KOI-2859.05 0.66[32]
KOI-3017.01 0.67[32]
KOI-4907.01 0.67[32]
KOI-1616.02 0.67[32]
KOI-6299.01 0.67[32]
KOI-8211.01 0.67[32]
KOI-2593.02 0.68[32]
KOI-4605.01 0.68[32]
KOI-7832.01 0.68[32]
KOI-7483.01 0.68[32]
KOI-2623.02 0.68[32]
KOI-7924.01 0.68[32]
KOI-7628.01 0.69[32]
KOI-4129.01 0.69[32]
KOI-4822.01 0.69[32]
KOI-6600.01 0.69[32]
Close

See also

References

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