What is the coldest known exoplanet?
The coldest known exoplanet is WISPIT 2 b, with an estimated equilibrium temperature of about -240°C (-399°F), cold enough to freeze most gases solid. Everything about WISPIT 2 b →
| # | World | Equilibrium temp | Distance |
|---|---|---|---|
| ★ 1 | WISPIT 2 b | -240°C (-399°F) | 440 ly |
| 2 | MOA-2007-BLG-400L b | -239°C (-398°F) | 22,472 ly |
| 3 | GJ 680 b | -237°C (-394°F) | 31.5 ly |
| 4 | Triton | -235°C (-391°F) | 0.0 ly |
| 5 | GJ 3512 c | -230°C (-382°F) | 30.9 ly |
| 6 | HD 153557 d | -230°C (-381°F) | 58.5 ly |
| 7 | Pluto | -229°C (-380°F) | 0.0 ly |
| 8 | GJ 15 A c | -227°C (-377°F) | 11.6 ly |
| 9 | HIP 948 b | -227°C (-376°F) | 114 ly |
| 10 | HD 29985 b | -226°C (-376°F) | 102 ly |
| 11 | GJ 317 c | -225°C (-374°F) | 49.6 ly |
| 12 | GJ 9714 b | -225°C (-374°F) | 66.9 ly |
| 13 | GJ 676 A c | -225°C (-373°F) | 52.3 ly |
| 14 | HIP 35965 b | -224°C (-372°F) | 164 ly |
| 15 | OGLE-2005-BLG-390L b | -223°C (-370°F) | 21,526 ly |
| 16 | GJ 849 c | -223°C (-369°F) | 28.7 ly |
| 17 | HD 105618 c | -222°C (-367°F) | 229 ly |
| 18 | HD 86065 b | -221°C (-365°F) | 132 ly |
| 19 | Charon | -220°C (-364°F) | 0.0 ly |
| 20 | GJ 433 c | -219°C (-363°F) | 29.6 ly |
| 21 | PZ Tel b | -219°C (-363°F) | 154 ly |
| 22 | HD 18143 c | -219°C (-361°F) | 73.5 ly |
| 23 | OGLE-2005-BLG-071L b | -218°C (-361°F) | 10,437 ly |
| 24 | HD 145675 c | -218°C (-360°F) | 58.5 ly |
| 25 | G 192-15 c | -217°C (-359°F) | 31.1 ly |
Showing the top 25 of 5,789 that qualify.
Cold records attract bad data, so this ranking has a floor: nothing in the universe can sit below the cosmic microwave background at about −270°C, and catalog rows colder than −243°C (30 kelvin) are treated as placeholder values and excluded. Disputed detections are excluded too.
For comparison, Pluto sits near −230°C. What could unseat this record: free-floating worlds found by microlensing, far from any star's warmth, are the likeliest challengers, but most have no measured temperature at all, and a world without a measurement can never hold a record here.
What is the coldest known exoplanet?
The coldest known exoplanet is WISPIT 2 b, with an estimated equilibrium temperature of about -240°C (-399°F), cold enough to freeze most gases solid.
How cold is the coldest known planet?
WISPIT 2 b sits at about -240°C (-399°F). At that temperature nitrogen and oxygen are solid, and the only thing keeping the world above absolute zero is the faint light of its star and the background glow of the universe itself.
Is there a limit to how cold a planet can be?
Effectively yes: about 2.7 K, the temperature of the cosmic microwave background, the leftover heat of the Big Bang that fills all of space. Nothing can passively cool below it, which is why this ranking treats catalogued values under 30 K as bad data rather than records.
How do you find a planet that cold?
Almost always by microlensing or direct imaging, the two methods that work far from a star. Cold planets sit on wide orbits where a transit is vanishingly unlikely and a full orbital wobble would take centuries to measure.
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