What is the coldest planet?

The coldest planet in the solar system is Neptune, although Uranus is also extremely cold and, in some conditions, appears colder in certain regions.

Temperature on Neptune

Neptune is the eighth and farthest planet from the Sun. Its average temperature is about -214°C (-353°F). Because it is so far away, it receives very little sunlight. Most of the heat inside Neptune comes from internal processes, but the outer atmosphere remains extremely cold.

Why Neptune is the Coldest

• Distance from the Sun: Neptune is about 4.5 billion kilometers away, so sunlight is very weak.
• Atmosphere: Made mostly of hydrogen, helium, and methane. Methane absorbs red light and gives Neptune its blue color, but it does not retain heat well.
• Winds: Neptune has the fastest winds in the solar system, reaching speeds of 2,000 km/h, which spread the cold across the planet.

What About Uranus?

Uranus, the seventh planet, has an average temperature of -224°C (-371°F). This makes Uranus, in fact, colder at its minimum temperatures than Neptune. The reason is that Uranus gives off very little internal heat, unlike Neptune.

So the title of “coldest planet” can be confusing:

• By distance, Neptune is the coldest.
• By minimum recorded temperature, Uranus is colder.

Key Differences

Conclusion

Neptune is usually considered the coldest planet overall because it is the farthest from the Sun and has freezing average temperatures. However, Uranus has even lower minimum temperatures in parts of its atmosphere. Both are colder than any other planet.