Uranus is one of the lesser-known planets, at least in this survey of one. In my childhood, I definitely learned more about our close cousins Mars and Venus than about the gas giants that inhabit the outer solar system.
Of course, Saturn’s rings and Jupiter’s Great Red Spot also featured largely in classroom discussions of the solar system. Uranus, however, got less attention. As far as I was concerned, Uranus was the poor, boring neighbor of its larger gas giant family members.
A bit of digging reveals that this is far from true. In fact, Uranus might be one of the most interesting planets in our galactic neighborhood. Read on while I illuminate this overlooked planet with 21 fascinating facts.
1. You’re Probably Saying It Wrong
Chances are good you’re not saying Uranus the right way, even if it does sound hilarious.
According to experts, “The standard way to pronounce Uranus among astronomers is to put the emphasis on the first syllable ‘ur’ and then say the second part ‘unus’. This is the standard literary pronunciation. The more common way people have pronounced it is u-ra-nus, with the ‘ra’ sounded like ‘ray’.”
2. It’s Visible to the Naked Eye, But Dim
Uranus is visible to the naked eye, but only barely. Because of this, it was not officially recognized as a planet until its discovery by William Herschel, using a powerful telescope, in 1781.
Now that we know where it is, it is possible to chart its course through the sky using the naked eye. However, if you didn’t know where to look, it’s unlikely that you would notice it against the backdrop of stars, moon, and other planets.
3. It Was the First Planet Found by Telescope
Mercury, Venus, Mars, Jupiter, and Saturn were all well-known to ancient peoples. They identified them as planets thousands of years ago because their patterns of movement across the sky were so different from stars.
While stars move in a steady up-and-away pattern from where they start on the horizon, the planets move in weird loops, often setting not too far from where they rose hours before. The Greeks called them “wanderers” or planetes, because of this habit.
With the invention of the telescope in 1608, humankind had the ability to look for new planets for the first time. It identified Uranus initially. Neptune and Pluto followed, a century apart, in 1846 and 1930, respectively.
4. It Was Discovered … When?
All right, I know I just said it was discovered in 1781 … but was it? According to the University of Chicago, some ancient peoples did know about this not-super-visible planet: “The Aztecs built pyramids for these planets, but they cannot be seen without a telescope.”
Other sources, however, debunk this idea. Jason Colavito explains that Hugh Harleston Jr. mapped Teotihuacan in 1970 and pinpointed sites that corresponded to various celestial bodies including the sun, moon, well-known planets, and even the later-discovered ones.
However, Colavito then adds, the monuments Harleston chose were “selected to conform to a predetermined framework and which later work mapping the site has discredited.” So much for that theory. Probably.
5. It Is Blue-Green Due to Methane
Uranus is blue-green in color, looking very pretty in its photos against the dark backdrop of space. This color stems from the high ratio of methane in the atmosphere, about 2.3 percent.
The methane’s ability to absorb lights on the warmer end of the spectrum (red, orange, and yellow) and reflect blue and green is what turns the planet such a cheerful aquamarine color. Most of its atmosphere, however, is made up of hydrogen and helium.
6. Uranus Has 13 Rings
Although they’re not easily visible, and must be imaged in the infrared in order to get a good picture, Uranus does have rings like other gas giants. However, they are very narrow compared to the glorious rings of Saturn.
Because they’re so hard to see and don’t reflect much sunlight – the typical way things in space become visible to cameras and our eyes – we didn’t know about Uranus’s rings until 1977.
7. … and They’re Multicolored!
Oh, did I mention that Uranus’s rings are multicolored? That’s right. They might not have the impressive technicolor glow that Saturn has going on, but its rings do range in hue.
As NASA explains, “Uranus has two sets of rings. The inner system of nine rings consists mostly of narrow, dark grey rings. There are two outer rings: the innermost one is reddish like dusty rings elsewhere in the solar system, and the outer ring is blue like Saturn’s E ring.”
8. That’s One Long Year
Uranus travels around the sun, just like Earth and the other planets. However, it’s real far away. That means the time it takes to complete one orbit of our home star – in other words, one Uranus year – is equal to 84 Earth years. Yikes.
9. It Has an Unusual Axial Tilt
One of the coolest facts about Uranus is that its equator is nearly at a right angle to its axis. In other words, if you were to stick a toothpick through its poles (determined by the axis of rotation) and then set it in orbit, the toothpick would point nearly straight ahead.
This is a big contrast to Earth, say, whose axis sits at an angle of 23.5 degrees, so that the toothpick is pointing mostly upward. The axial tilt of Venus is very extreme, at 177 degrees, while Mars is much closer to Earth at roughly 25 degrees.
10. Somebody Had an Accident
How did this happen? Most likely because Uranus had an encounter with an Earth-sized object that knocked it off the more typical upright axis. As it stabilized, it did so with its axis of rotation pointing in the direction of travel.
Why does axial tilt matter at all, you’re wondering? Seasons, my friend.
11. Extreme Seasons Rule Uranus
The relation of Uranus’s tilt to its seasons is hard to visualize, but this image helps. Because Uranus’s passage around the sun takes so long, its seasons are roughly 21 years long. And because of its tilt, its poles point directly at the sun for more than two decades at a time.
This leads to some of the most extreme seasonal weather in the solar system, including – drum roll, please – diamond rain.
12. Diamond Rain?!
Yes, it rains diamonds on Uranus. For real.
Why? It’s a little confusing, but essentially, diamonds are made of carbon atoms that get compressed under extreme pressures and temperatures. While Uranus is very cold at the surface – more on that below – things get much hotter far beneath its methane clouds.
There, the environment is sufficient to force carbon atoms to crystallize into diamond. Because they are heavier, these then crystallize and fall out of the atmosphere as rain.
World Atlas adds that “some models predict that Uranus and Neptune may have layers of liquid diamond, accompanied by large diamond-bergs.” That alone is likely motivating many of the space technology entrepreneurs in business today.
13. Midnight Sun on Uranus
Diamond rain isn’t everything, though. Because of the way Uranus travels around the solar system, its poles are in darkness for a full quarter of their orbit (winter), and in sun for another quarter (summer) – 21 years each.
If you compare this to the midnight sun in Norway at only 76 days, that’s pretty impressive. Same with the polar night – that long stretch where the sun never rises once.
14. Spring and Fall Have Days Just Like Us
Rather than pointing in just one direction and experiencing light or darkness on just one side, as with summer and winter, spring and fall have normal days.
Because the equator is facing the sun rather than the poles, the planet spins parallel to the sun and so the sun appears to rise and set from the point of view of a person on the surface.
The day-night cycle on Uranus is about 17 hours long. As with autumn and spring here on Earth, the changing temperatures mean lots of storms and unsettled weather. In spring, for example, “There are hurricanes larger than half of the United States, and temperatures dip below -300 ° F!”
And that happens for the next 21 years.
15. Uranus Has a Twin
The planet Neptune has many features and attributes in common with Uranus, including:
- Diamond rain: Yep, twice in one solar system. In fact, while diamonds are rare on Earth and therefore pricey, it’s not that hard to find them in the outer solar system.
- Rings: Neptune also has rings, though they’re more significant than Uranus.
- Size and composition: Uranus and Neptune are relatively similar in size and general composition. Though they have many differences, they are like Earth and Venus in this way: located next to one another and sharing many features, but still very different.
16. … But It’s a Fraternal Twin
Despite similarities in their size, mass, and atmospheres, Neptune and Uranus do vary significantly in terms of their appearance. While Uranus is a light blue-green that sometimes appears almost grey, Neptune is a bright blue.
Why? Most likely because, while both planets have methane atmospheres, Uranus’s middle layer is twice as thick as Neptune’s. It gives the planet a more opaque look than Neptune, leading to the major color differential.
17. In the Spin Zone
Most planets spin from East to West, but not Uranus. It actually spins West to East, which means if you lived there, you could expect the sun to rise in the West each morning. We don’t know why this is, though it could have something to do with the same accident that made its axis of rotation so wonky.
The only other planet that has this direction of rotation is Venus.
18. Uranus Honors the Sky
“Uranus” comes from the Greek name for the god of the sky, whom the Romans called Caelus. This might not seem unusual, but it is, since most planets are named for Roman gods.
Mercury, Venus, Mars, Jupiter, Saturn, Neptune, and Pluto are all Roman names. Their Greek counterparts are Hermes, Aphrodite, Ares, Cronus, Zeus, Poseidon, and Hades. It’s unclear why Uranus is the only planet (aside from Earth) that did not inherit a Roman name.
19. It’s Not William Herschel’s Fault
William Herschel did not name the planet Uranus at all. His name for it was the Georgium Sidus, which means “Georgian planet,” meant to honor King George III of England.
A German astronomer named Johann Elert Bode later proposed Uranus to align with the other planets’ classical names. Why he did not choose Caelus is anyone’s guess.
20. Uranus Has a Lot of Moons
As of our current knowledge, Uranus has 27 moons. According to NASA, “All of Uranus’ inner moons appear to be roughly half water ice and half rock. The composition of the outer moons remains unknown, but they are likely captured asteroids.”
21. … and They’re Oddly Named Too
As with Uranus itself, the moons buck the naming traditions. The moons of other planets borrow from Roman and Greek mythology. There are hundreds of them, so the namers probably needed to widen their scope.
However, Uranus’s significant collection of moons deviates sharply. They’re all named for characters from William Shakespeare’s works or those of Alexander Pope, the lesser-known but equally brilliant poet who lived between 1688 and 1744.
Among these are names such as Bianca from The Taming of the Shrew, Ariel from The Tempest, and Juliet from … well, I hope you know that one. Other distinctly non-classical names include Ferdinand, Margaret, Ophelia, and Francisco.
Entertain Others With Your New Uranus Knowledge
Now that you know as much as I do about this beautiful blue-green planet, I hope you’ll carry this message to others who will enjoy learning about it.
And when you look through a telescope next, try and hunt down this unique addition to the solar system we call home!