Coldest planets in the solar system
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Coldest Planets in the Solar System: Temperature Extremes and Key Examples
Temperature Ranges of Outer Solar System Planets and Moons
The coldest planets and moons in our solar system are found far from the Sun, where sunlight is weak and temperatures drop to extremely low levels. Uranus and Neptune are the coldest major planets, with Uranus’s moons Oberon and Titania reaching temperatures around 60 K, and Neptune’s moon Triton being even colder at about 35 K, making it the coldest known moon in the solar system. For comparison, Jupiter’s moon Callisto is about 120 K, and Saturn’s moon Titan is around 90 K. Even the dwarf planet Ceres, located in the asteroid belt, is colder than Antarctica, with temperatures near 167 K .
Cold Gas Giants: Uranus and Neptune
Among the gas giants, Uranus is often considered the coldest planet in the solar system, with atmospheric temperatures dropping as low as 49 K. Neptune, while farther from the Sun, has a slightly warmer atmosphere due to internal heat, but its moon Triton holds the record for the coldest surface temperature .
Cold Terrestrial and Icy Worlds
Some small, distant objects and moons also reach extremely low temperatures. For example, the surface of Neptune’s moon Triton is only about 35 K, and Uranus’s moons can be as cold as 60 K . These temperatures are much lower than those found on any planet or moon closer to the Sun.
Cold Exoplanets and Their Relevance
While not part of our solar system, studies of cold exoplanets help us understand the temperature extremes possible for planetary bodies. For instance, the exoplanet WD 1856+534 b, orbiting a white dwarf, has a temperature of about 186 K, similar to the coldest solar system planets, and is the coldest exoplanet from which light has been directly observed . Additionally, cold terrestrial exoplanets with temperatures below 60 K have been detected, showing that such frigid conditions are not unique to our solar system .
Cold Ocean Planets and Subsurface Activity
Some cold planets and moons may have subsurface oceans beneath their icy crusts, kept liquid by internal heating. This is seen in icy moons like Europa and Enceladus, and is also predicted for cold exoplanets such as Proxima Cen b and TRAPPIST-1f, which may have thin ice shells and active geological processes despite their frigid surfaces .
Conclusion
The coldest planets and moons in the solar system are found in its outer reaches, with Uranus, Neptune, and their moons—especially Triton—setting the record for the lowest temperatures, sometimes as low as 35 K. These frigid worlds provide important insights into planetary science, and similar cold conditions are observed on some exoplanets, expanding our understanding of the diversity of planetary environments 1478.
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