Facts About Uranus: The Heavenly Ice Giant

While its unique name might make it joke-worthy, Uranus — the seventh planet in our solar system — is one of the most curious gas giants that we’ve ever seen. From its composition to its color, there is no shortage of fascinating tidbits about this strange place. There is also still so much humanity doesn’t know about Uranus that makes it one of the most interesting opportunities to learn more about our Solar System. What makes it so different? Here are some interesting facts about Uranus that you need to know.

10 Interesting Facts About Uranus

Let’s start with some rapid-fire tidbits.

1. It Gets Its Name From the Greek God of the Heavens

Uranus is the only planet in the solar system named for a Greek god instead of a Roman one. William Herschel, the astronomer who discovered it, originally wanted to name it “George’s Star” after King George III, but that didn’t stick. Uranus is the Latinized version of Oranous, the Greek god of the sky and grandfather of Zeus.

According to the mythology, Uranus is the personification of the heavens, created at the origin of the Earth goddess Gaea. Upon her emergence from Chaos, she produced Uranus (the heavens) and the rest of the world, including the mountains and oceans. Gaea birthed several troublesome children with Uranus, including the Titan and Cyclopes. Uranus deeply resented his children until they sought recompense. The most prominent child of his, Cronus the Titan, attacked him and is the reason Earth and the heavens are separate realms.

2. It’s the Coldest Planet in the Solar System

Despite being closer to the sun than Neptune or Pluto, Uranus is the coldest planet in the solar system. It tends to sit at an average of -197 degrees Celsius but we’ve recorded temperatures on the blue planet as low as -224 C or -371.2 degrees Fahrenheit. 

Why is it so chilly? You might think distance from the ever-boiling Sun would equate to colder temperatures. However, Uranus has another problem. Many planets generate heat internally, but Uranus doesn’t. This means most of its warmth, if you can even describe it as such, is almost solely from the Sun, billions of miles away.

It isn’t able to generate much heat because of this next fact.

3. The Planet Orbits On It Side

On Earth, we have an orbital tilt of about 23 degrees. That’s what gives us our seasons, but on Uranus, the orbital tilt is an astonishing 97.77 degrees! The planet looks like it’s rolling around the solar system on its side, with it’s equator at a right angle to its orbit. 

This is because Uranus was part of an unprecedented collision with another space object, like an asteroid, billions of years ago. The force was so intense it knocked it over in a way, forcing it to release the heat it used to be able to contain. Many planets still harbor heat from when they were created, but Uranus doesn’t have this luxury.

4. It’s Also Called the Ice Giant

Unlike Jupiter and Saturn, Uranus has a thin outer atmosphere of hydrogen, helium and methane, surrounding a heavier layer of other elements including ice and water.

Both Neptune and Uranus are classified as ice giants, even though they were previously described as gas giants. Their molecular composition lends these planets to having a powerful magnetic field and irregular seasonal patterns.

5. It Has Two Sets of Rings

Like most of the outer planets, Uranus also has rings though they might not be as fancy as the ones orbiting Saturn. There are currently two sets of rings, with 13 in total, orbiting the ice giant. They’re mostly made up of small dark pieces that reflect almost no light, making them nearly impossible to see with traditional telescopes. 

The ring system has an inner and outer set, varying in thickness and color. Like other planetary rings, they contain mostly ice and dust particles. Its most famous ring is the Epsilon ring, because it is the brightest.

6. It Has 28 Moons

While it doesn’t come close to Jupiter or Saturn when it comes to the number of moons, Uranus still has plenty. Its moons are named for literary characters from the works of Alexander Pope and William Shakespeare, with names like Titania, Miranda, Oberon and Ariel making an appearance. 

This is one of the best examples of how experts are still learning new things about Uranus’ moons. It was common knowledge the planet had 27 moons, with its 28th being discovered in November 2023. It took them months to decide a name that continued with its literary naming conventions. They decided upon the Shakespeare character Violenta.

How many more moons could Uranus have in the near future? Thankfully, we still have a lot of Shakespeare names to go through.

7. It Gets Its Blue Color From Methane

Uranus is a brilliant blue, a color which it gets from the methane in its outer atmosphere. It’s mixed with helium and hydrogen, but it’s the methane that absorbs the red light from the sun, reflecting the blue and giving the planet its iconic color. 

8. You Can See It With The Naked Eye

It might sit on the outer edges of our solar system, but if you’ve got a dark night and little to no light pollution, you can actually spot Uranus with the naked eye. It’s just barely visible — and you won’t see it at all if there’s any artificial light — but you can see the little blue-green dot with the naked eye if you know where to look. 

9. We’ve Only Been There Once

We’ve only sent one spacecraft into the outer reaches of the solar system that observed Uranus — Voyager II. It passed close to the planet on January 24th, 1986 before heading off to Neptune and parts unknown. NASA considered sending the Cassini probe there after it was done with Saturn but chose not to.

In the last decade, researchers have attempted to pose more exploratory missions to the planet, but none have been approved. Efforts began ramping up in 2017 and continue to his day, with waxing and waning interest. Whatever humans do send to the planet wouldn’t be able to penetrate its dense atmosphere. The extreme pressure, winds and temperatures would make it a precarious adventure. Even though it is an ice giant, not gas, it still wouldn’t be able to land and explore in a way the Mars Rover has — not with current technology.

10. Uranium is Named After It

Martin Klaproth discovered Uranium in 1789, eight years after the discovery of Uranus. The chemist named the radioactive element after the distant planet. 

Uranus Properties & Information

• Location in Solar System: Seventh Planet
• Distance from Sun: 2,870,658,186 km or 19.22 AU.
• Composition: Small rocky core surrounded by layers of methane, hydrogen, and helium.
• Size: 51,118 km at the equator
• Surface: No discernible surface
• Structure: A gas giant with a rocky core
• Color: Blue
• Atmosphere: Water, methane and ammonia
• Moons: 27, primarily named after literary characters
• Temperature: -197 C or -322.6 F
• Orbital Period: 84 years
• Rotation Period: 17 hours at the equator, up to 42 years at the poles

Who Discovered Uranus?

This is one planet that unless you know where to look, is nearly impossible to see with the naked eye. We didn’t officially discover it until Sir William Herschel found it in 1781. Herschel actually tried to name the new planet “Georgian Sidus” for the currently reigning King George III, but no one outside of England was a fan of that moniker. 

Eventually, astronomer Johann Bode suggested Uranus, named for Oranous, the Greek god of the sky who fathered the titan Chronos and was grandfather to Zeus. It’s also the only planet named for a Greek god instead of a Roman one. 

We’re grateful to Bode for suggesting a different name for the ice giant. Can you imagine rattling off the planet’s in the solar system if Herschel’s name had stuck? Jupiter, Saturn, George, Neptune, Pluto just doesn’t have the same ring to it. 

What is Uranus Known For?

Uranus is most known for its brilliant blue color, thanks to the methane in its atmosphere which absorbs the red wavelengths of light coming from the sun. What we see is the visible blue light reflected back, giving the ice giant it’s iconic color. 

It’s also known for likely having liquid water beneath its upper atmosphere. When Voyager flew by the planet in 1986, it didn’t look like much from the surface — until the probe found evidence that some 500 miles below the outer atmosphere, the coldest planet in the solar system actually has boiling oceans. 

Unfortunately, it’s also known for its name being the butt of all sorts of jokes, but that shouldn’t discourage you from studying this awesome ice giant. 

What Makes Uranus Unique?

The most unique thing about Uranus is its incredible orbital tilt. The planet is basically orbiting the sun on it’s side, with a tilt of 97.77 degrees. Its equator is essentially at a right angle to its orbit and its magnetic field is twisted, with a magnetic tail that stretches in a helix-shape for something like 6 million miles and pointing away from the sun.

It’s ice giant status also makes it unique. Unlike Saturn and Jupiter, which have a small rocky core and are made up of hydrogen and helium, both Neptune and Uranus are classified as ice giants. They have a molten rocky core and an outer atmosphere that includes helium and hydrogen, but also includes a variety of other elements as well as ice and even liquid water. Astronomers started using the ice giant designation in the 1990s when they discovered that Neptune and Uranus were composed differently than the two other gas giants in the solar system. 

Uranus also has some of the longest and strangest seasons in the solar system. You can enjoy a short 17 hour day during the spring and fall seasons. During the summer, you’re looking forward to 21 years of non-stop daylight, and 21 years of the endless night during the winter. It doesn’t sound like somewhere we’d want to spend a summer vacation!

Looking Forward

Uranus is the seventh planet in the solar system, which means we’ve nearly reached the end of our journey through our local celestial neighborhood. We’ve got two more stops — at least if we’re talking about planets. Neptune and Pluto are still out there waiting for us. Tag along while we make our way to the edge of the solar system. Maybe we’ll even jump outside the heliosphere and see what lies beyond, in that empty space between solar systems that we haven’t been able to explore yet. 

Featured Image Credit: NASA / Lawrence Sromovsky, University of Wisconsin-Madison/W.W. Keck Observatory

Editor’s note: This article was originally published on October 6, 2020 and was updated November 29, 2024, to provide readers with more updated information.