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 |
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.
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