Is Uranus the Coldest Planet in our Solar System? 12 Interesting Facts about Uranus

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Updated on: Educator Review By: Michelle Connolly

What is the coldest planet in the solar system? You may be confused between Uranus and Neptune, the most distant planets. Technically speaking, Neptune is the coldest planet in the solar system, but Uranus does reach the coldest temperatures of any other planet.

Introduction to Uranus

Uranus is one of the eight planets that orbit the Sun in our Solar System. It is the seventh planet from the Sun, between Saturn and Neptune, and the third-largest planet in the Solar System. The average distance between Uranus and the Sun is about 2.9 billion kilometres. Uranus is an outer planet and a gas giant along with Neptune, Saturn, and Jupiter. However, both Uranus and Neptune have different compositions than the two other gas giants, so they are called ice giants. 

Uranus and Neptune
Uranus and Neptune are the ice giants

Surface and Structure

Uranus is one of the gas giant planets, which means that it is made up mostly of gases, and it does not have a solid surface. The main two gases that make up Uranus are hydrogen and helium. Around 80% of the mass of Uranus is made up of dense, hot fluid of icy materials including water, methane, and ammonia. Inside Uranus, it is believed that there are two layers, which are the core and a mantle. Scientists think that the core is mostly made up of rock and ice, and the mantle is made up of water, ammonia, and other elements.

Atmosphere and Temperature

Uranus’ atmosphere consists mostly of hydrogen and helium, like Jupiter’s and Saturn’s. However, it contains more icy material such as water, ammonia, methane, and other gases. The gas atmosphere makes up about 25% of the planet. This atmosphere is stormy, but not as stormy as that of Saturn or Jupiter. As a result, the surface of Uranus is plain and does not have features. Some of the wind speeds recorded on Uranus were among the most powerful winds that have ever been witnessed in the Solar System. 

The atmosphere of Uranus is the coldest atmosphere in the Solar System. Its average temperature is around -371 °F (-224 °C). The average temperature on Uranus is -325 degrees. Near the core inside the planet, the temperatures reach 9,000 °F (4,892 °C). This is the lowest temperature of a giant planet’s interior. However, the reason why temperatures on Uranus are very low is not yet understood, and scientists are trying to find out the reason. There may be something that prevents the heat from the core from reaching the surface of the planet.


Uranus is the third largest planet in the solar system. Its diameter is about 51,000 kilometres. That is about four times the diameter of Earth. Uranus is slightly larger than Neptune, its outer neighbour, yet it is smaller in mass. Uranus has 10 times the diameter of Mercury, the smallest planet in the Solar System. Jupiter, the largest planet in the Solar System, has 2.8 times the diameter of Uranus.

planets in the solar system

Orbit and Rotation

Like all planets, Uranus has two types of motion: orbit around the Sun, and spin about its centre. It takes Uranus about 84 Earth years to complete one orbit around the Sun. In other words, a year on Uranus equals about 84 Earth years.

Uranus spins about its centre in an unusual way. It is tilted; so, it spins on its side unlike any other planet. Also, like Venus, Uranus rotates in the opposite direction than most other planets, from East to West. It takes Uranus about 17 hours to complete a spin about its centre, so a day on Uranus lasts about 17 hours.

Uranus for Kids
Uranus for Kids


There are 13 known rings surrounding Uranus, but they are difficult to observe. They are not like the bright rings of planet Saturn. The rings are divided into two sections, the inner rings and the outer rings. The outer rings are bright, colourful and easy to see, while the inner rings are narrow and very faint.


Scientists have discovered 27 moons orbiting Uranus until now, and there may be more. All of those moons are very small, and they seem to be made of ice and rock. Some of them have deep valleys and many craters. The five major moons are Oberon, Titania, Ariel, Umbriel, and Miranda. The biggest moon of Uranus is Titania. It is the eighth largest moon in the Solar System. Miranda is one of the strangest objects in the solar system for its irregular landscape and strange patterns.


The planet Uranus is named after the ancient Greek God of the sky. In Greek mythology, Uranus was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of Cronus (Saturn).

Discovery and Exploration

Uranus cannot be seen with the naked eye from Earth without using a telescope. The astronomer William Herschel discovered Uranus using his telescope in 1781 in Great Britain. The rings were discovered in 1977. Only one spacecraft has visited Uranus until now. It was the unmanned spacecraft Voyager 2, which flew by Uranus in 1986.


Facts about Uranus

  1. Uranus was the first planet to be discovered in the modern age after the invention of the telescope.
  2. Uranus is sometimes visible in the sky and can be seen without a telescope, but you can only view it on a very clear night sky.
  3. Both Uranus and Neptune share similar compositions, and they differ from the other gas giants Jupiter and Saturn. Scientists have classified Uranus and Neptune as ice giants rather than gas giants because of this similarity. 
  4. Although Uranus is larger in size than Neptune, it is smaller in weight.
  5. Uranus is the second least dense planet in the solar system, after Saturn.
  6. In 2033, Uranus will complete its third orbit, or year, around the Sun since its discovery in 1781.
  7. The distance from the Sun to Uranus is 20 times farther away than that of Earth.
  8. Uranus appears to be bright blue in colour, and that is because of the methane gas. 
  9. All of the moons around Uranus have dark surfaces, and they are all frozen.
  10. The biggest moons of Uranus together have surface areas smaller than the continent of Australia.
  11. The Uranian moons are named after fictional characters created by Alexander Pope and William Shakespeare. 
  12. The rings of Uranus have probably formed around 600 million years ago from the collision of moons or other big celestial objects.

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