Uranus is the coldest planet in our solar system, even though Neptune is much farther from the Sun.

Uranus holds the record for the lowest temperature ever recorded in the solar system, reaching a frigid -224°C (-371°F). This is surprising because Neptune is approximately 1.6 billion kilometers (1 billion miles) farther from the Sun than Uranus. While distance usually dictates temperature, the internal heat of a planet plays a critical role in its atmospheric climate.Most gas giants, like Jupiter and Saturn, generate significant internal heat through gravitational contraction and radioactive decay. Neptune also radiates about 2.6 times more energy than it receives from the Sun. In contrast, Uranus radiates almost no excess heat into space, making it unique among the outer planets. This lack of internal warmth is why its atmosphere can drop to such extreme lows.The leading theory for this anomaly involves a catastrophic event during the early formation of the solar system. Astronomers at Durham University and other institutions suggest that a proto-planet roughly twice the size of Earth collided with Uranus about 4 billion years ago. This impact was so violent that it tilted the planet 98 degrees onto its side.This massive collision likely disrupted the planet's internal structure and caused its primordial heat to dissipate rapidly into space. Another possibility is that the impact created a layer of debris that acts as an insulator, trapping heat deep within the core and preventing it from reaching the surface. Data from the Voyager 2 flyby in 1986 confirmed these low temperatures, and modern infrared telescopes continue to study this thermal mystery.