The coldest natural thing on Earth is the Boomerang Nebula, which is located about 5,000 light-years away from Earth. This nebula has a temperature of just 1 Kelvin (-272.15°C or -457.87°F), making it colder than even the background temperature of space.
The extreme cold is due to the rapid expansion of gas from the central star, which causes the temperature to drop significantly. This phenomenon is similar to how a refrigerator works, where expanding gas cools down the interior.
On Earth, the coldest natural temperatures are found in Antarctica, where temperatures can drop to around -89.2°C (-128.6°F). However, these temperatures are still much warmer compared to the Boomerang Nebula.