The last two planets of the solar system, Neptune and Uranus are so far away from the Sun that no considerable heat reaches them. Neptune is 2.8 billion miles away from the Sun and is the farthest planet. Uranus is 1.8 billion miles away from the Sun and is the second last planet. Uranus is not the farthest planet from the Sun but still holds the record for the lowest recorded planet temperature. Uranus has thus earned the title of ‘coldest planet in the Solar system’.
Uranus – the coldest planet in the Solar system
Uranus is the coldest planet in the Solar system. The lowest temperature recorded on Uranus is as low as -224°C/-371°F. However, when it comes to mean temperatures, Neptune is the coldest planet. The mean temperature on Neptune is around -201°C/-330°F while the mean temperature on Uranus is around -195°C/-320°F.
Why is Uranus so cold?
1. The temperatures on Uranus are so low primarily because of its large distance from the Sun.
2. Uranus has an axial tilt of about 98 degrees. You can imagine Uranus rolling on its orbital plane around the Sun. This unusual tilt is believed to be caused because of a collision with another astronomical body. Due to this collision, a large amount of core heat might have released from Uranus. Uranus has a relatively lower core temperature of less than 5000 °C. Neptune on the other hand has a core temperature of 7000 °C.
Also due to this unusual tilt, for a quarter of the Uranian year i.e. 21 Earth years, a polar side faces the sun while the other side goes into long, cold winters. This is another reason why Uranus has the coldest recorded temperature.
Pluto, once considered a planet, now a dwarf planet is even colder than Uranus and Neptune. The mean temperature on Pluto is -225°C/-375°F. The lowest recorded temperature on Pluto is as low as -240°C/-400°F.
Triton is a Moon of Neptune. The temperatures on Triton drop below -240°C/-400°F. Triton is thus the coldest major astronomical body in the solar system.
The average temperature on Earth’s moon is higher than the colder solar system bodies. However, the side of Earth’s moon not facing the Sun gets extremely cold. The temperatures recorded on some craters of the moon are lower than Pluto’s average temperature.