Yes, yes, rings around Uranus, haha

By Phil Plait | August 23, 2007 12:46 pm

Poor Uranus. Besides having a name guaranteed to make 12-year-old-boys giggle*, to most people it lacks any sort of interest. It isn’t huge, like Jupiter, or bright, like Venus, or shine with a striking red color, like Mars. It doesn’t have giant glorious rings like Saturn… but it does have rings, and sometimes they can be pretty cool too.

Uranus orbits the Sun once every 84 years (hey, I’m 6 Uranus months old!), and that means that once every 42 years, the Earth and Uranus line up in just the right way that we see those rings edge-on. That’s useful– it can help us measure how thick the rings are, for one. For another, very faint parts of the ring can be seen more easily since the brighter main rings don’t drown them out.

Earth passed through Uranus’s ring plane in mid-August. Since the rings were only discovered in 1977, it’s the first time this event has ever been studied! Several telescopes were trained on the green giant to see what they could see, and that includes Hubble. On August 14, just a week ago, here is what it saw:

How cool is that? The inner and outer rings can both be seen (the outer rings were discovered in 2005 in a Hubble image; humorously they were in an earlier 2003 image but overlooked because they were so faint). The fan shape in the image is scattered light from the planet itself. Oh– note the scale bar, showing 20,000 miles/32,000 km. The Earth, for a sense of scale, is 8000 miles/12,800 km across.

Hubble wasn’t the only ‘scope to gander at the planet. From the Keck 10-meter ‘scopes in Hawaii, here is a long tease of the coy Uranus as it slowly and shyly turned sideways over 7 years:

As Uranus regally orbits the Sun, we slowly get a different view of those rings. Those images were taken in the infrared, and in some of them you can see bright spots on the planet, which are clouds and storms. In the earlier images you can see that there are many rings, like Saturn, but that gets harder to see as our view gets narrower.

Did I mention that Uranus was 2.7 billion kilometers away when these images were taken? Man, that’s a long way off.

In the above Keck image, we’re zoomed in a bit. The rings are labeled (Epsilon is the brightest, and Zeta the closest to the planet surface). What struck me with these images is that in the last one, you can see a bright spot in the rings. That means they aren’t smooth, like Saturn’s! They’re lumpy. Some locations in the rings have more junk in them than others.

Uranus’s rings, like Saturn’s, aren’t solid: they’re made of up of countless chunks of ice. The rings of Uranus are darker than those of Saturn, and I think thicker (at SpaceFest last week, Carolyn Porco noted that Saturn’s rings are literally a few meters thicks, yet hundreds of thousands of kilometers across). As we passed through the ring plane, we saw first the part of the rings where the Sun was shining down on them, and then after we passed through the plane we saw the dark side of the rings. These images are the first time anyone has ever seen this!

Astronomers will use these data to determine better the size, shape, and composition of the rings. Even though the Voyager 2 probe sped past there and took close up images, and we’ve been observing from Earth for years, there are still many mysteries about them. What is the source of the rings? Are there moonlets in the rings, like in Saturn’s, shepherding them and helping to keep them neat and narrow?

Uranus has been the butt of jokes for years (yes, I know, haha, spare me please) but in fact it’s a pretty cool place and worthy of a closer look… at least once every 42 years.

*The only time that I laughed at a Uranus joke (well, besides a few MST3K episodes) was in Futurama, when the professor invented a telescope that allows you to smell astronomical objects (called a smelloscope, natch):

FRY: This is a great, as long as you don’t make me smell Uranus. Heh heh.
LEELA: I don’t get it.
PROFESSOR FARNSWORTH: I’m sorry, Fry, but astronomers renamed Uranus in 2620 to end that stupid joke once and for all.
FRY: Oh. What’s it called now?


Comments (62)

  1. Astrogeek

    Ah, Farnsworth is right, that’s MUCH better.

  2. Chip

    Hypothetically, if planet Uranus was located where planet Mars is, at its closest to Earth, would amateur astronomers (and professionals) be able to see the Uranus rings in backyard telescopes? (Assuming the planet is tilted relative to us.)

  3. That smelloscope joke can be found on Youtube here:

  4. aiabx

    I keep a rubber mallet beside my telescope to use on people who repeat the 3 cursed jokes of amateur astronomy:
    1) I bet you see lots of heavenly bodies in your neighbour’s windows
    2) Any variation on the penis size/telescope size relationship
    3) Has anyone seen the rings around Uranus?

    But I also laughed really hard at Urectum – almost as hard as I laughed at the race with the quantum finish.

  5. Rjones

    I was going to quote that joke here but you beat me to it. One of my favorite Futurama jokes. It’s clever and scatalogical at the same time.

  6. Anytime someone makes a Uranus joke around me, I just respond by telling them that they’re pronouncing the planet’s name incorrectly.

  7. Olive

    Candice- it works better if you combine it with the the Futurama joke- “You’re saying it wrong. Geez. YOUUUUR-EKT-UHMMMM. Come on, you sound like a 12-year old.”

    If you can get a “your mom” joke in there, all the better.

  8. Thomas Siefert

    There used be some condom vending machines with Uranus as a logo, certainly hope they dispensed more than just the rings.

  9. Mark Martin


    Earth’s orbit has a radius of 1 AU. Mars’s is 1.52 AU. Uranus’s is 19.22 AU. So placing Uranus on the Martian orbit brings it closer to Earth’s orbit by a factor of 28/1000ths. By the 1/r^2 law, the brightness of a surface element will increase by a factor of 1,275, or about 7.76 astronomical orders of magnitude brighter. That alone is quite a lot. But on top of that, Uranus would be closer to the source of its illumination, the Sun, by a factor of 79/1000ths, making the rings intrinsically brighter by a factor of 160, or about another 5.5 orders of magnitude. In all a ring surface element would be brighter (as seen from Earth at opposition) by a factor of 204,000. I’d say they would be visible.

  10. Candice:
    “Anytime someone makes a Uranus joke around me, I just respond by telling them that they’re pronouncing the planet’s name incorrectly.”

    To which I reply, “What makes you think I’m talking about the planet?”

  11. A small questionette.

    Saturn and Uranus have rings, as, I believe, does Jupiter. Without looking it up in my text books, I’m not sure about Neptune.

    So, are rings regular companions of gas giants?

    And I didn’t think Saturn’s rings were smooth. What about the spokes in them? And isn’t the outermost ring only partial (an arc rather than a ring).

    I suppose I’m really asking if rings like this are actually commonplace for larger planets. Until we have more evidence for other planetary systems, I believe we will only be hypothesising.

  12. Chip

    To: Mark Martin
    I appreciate your explanation and the numbers involved. Thank you!

  13. Miranda

    Uranus gets a bum deal (hee hee)

    It is secretly my favourite planet. The only problem is that I can’t tell anyone that because they make “your-anus” jokes all the time … it’s so sad! My first and favourite memory of Uranus was the Voyager 2 photographic evidence of the rings. There was an awesome photo, taken by V-2, looking back at Uranus towards the sun. The picture shows the rings backlit, plus in the distance, a very small sun. That shot of the sun was the first time I really remember appreciating just want kinds of distances we were talking about. It was so cool! I ripped the photo out of a magazine, framed it and hung it on my wall for years.

    Then, to top it, were the initial images of the moon Miranda, with it’s battered and cratered surface. An astronomical mystery, and another favourite was born! It bears mentioning that it also around this time that I read about the technical issues being had by the V-2 cameras, and how they had to take these 2-hour+ exposure photos using the V-2 thrusters to keep the camera facing the object of interest, because the camera was broken and couldn’t turn itself. How cool was that!?

    Except that now when I want to tell people about the wonder of Miranda, I first have to tell them it’s a moon of Uranus … and wonder is lost in favour of butt humour … sheesh.

    ps Never saw the futurama bit before, but I loved it! thanks!

  14. Mia

    Whatchoo mean it lacks any sort of interest? Its axis is tilted on its side, dammit! The sun goes spiralling across the sky from pole to pole and back each year! The people must be told.

    Also, I vote we go back to calling it “George.” Yeah, yeah, har, har, “Uranus,” but c’mon–GEORGE. To hell with King George, III himself, but it’s a great name for a planet.

  15. Michelle

    Ah yes, that Futurama joke was one of the best. I laughed very loud at it.

    I always liked the planet Uranus myself.

  16. Cyberax

    English is not my native language, so the first time I’ve watched Futurama the joke about Uranus went over my head. I’ve laughed my head off then my friend explained this joke to me afterwards.

  17. GaterNate

    I propose we all begin pronouncing it oo-RAN-us. Sounds almost like a sci-fi name, like it should have an apostrophe in it somewhere. Plus it’s a hell of a lot cleaner sounding that your-AIN-us, or Urine-ous as they tried to get everyone to say in the ’80s.

    It’s one of my favorite planets too. I like it’s moons in particular. Of course if your with a group nobdy wants to say, “I wanna see Uranus! Right now!”

  18. For God’s sake….

    We all know it has an amusing name. So has Pluto (oh, what fun we had with Mickey Mouse jokes with that one).

    Doesn’t matter what we call it. Herschell called it George when he originally discovered it.

    Names don’t matter. Let’s look at the science here folks.

  19. Grand Lunar

    I use a similar pronounciation to your idea; GaterNate. I call it “u-RAN-us”.

    The planet looks a little bland in those images. I though Uranus turned how to have bands in it’s atmosphere (at told in a Universe Today article). Or is this a different wavelength where they are not visible?

  20. Chip

    Years ago, my Astronomy professor at ASU once mentioned that everyone mispronounces Boötes. He hated “Boo-teez” as in “Booties” like little boots. It is actually from the Greek “boʊˈoÊŠtiz” which is even mispronounced in internet audio sound files. He insisted it is: “booWahtis” with “emPHAsis” on the “seCOND” “syLAble”.

    Whether this is right or not, it sounds much cooler. However, he also pronounced Uranus as “YOURanis”. 😉

  21. In Indonesia we pronounced it oo-RUN-oos. No anal jokes there!

    A bit surprised nobody has mentioned Douglas Adams before. Come on, folks! The question of which the answer is 42 is right before us.

    Uranus = the Greco-Roman creator god; the mice constructed the earth as a computer to compute the question whose answer is 42, and place it in such an orbit that the rings of Uranus can be seen edge-on every 42 revolutions..

  22. “Candice- it works better if you combine it with the the Futurama joke- “You’re saying it wrong. Geez. YOUUUUR-EKT-UHMMMM. Come on, you sound like a 12-year old.”

    If you can get a “your mom” joke in there, all the better.”

    Yo Mama’s so fat the only thing she can fit in is Unanus!

    Okay, I didn’t say it was good…

  23. URanus, above. Not UNanus.

  24. urectum?

    Nope, I killed him! :)

  25. KaiYeves

    Yeah, and when you do geography in school, all the boys giggle when you say “Faulkland Islands” (It can sound like a swear word). The first time I heard the first joke that aiabx mentioned was on CatDog-
    “What are you doing with that telescope?”
    “Observing heavenly bodies, go away.”
    “You can see the beach with that thing?”
    It was funny that ONE time and never again. I always correct people’s pronunciation of Uranus, especially at a camp where I was a councilor last week. All gas giants in our solar system have rings, but I don’t know if we know this to be typical, Selina Morse. The only Uranus joke that I’ve ever found funny was this one that I made up myself:
    One of Carl Sagan’s most famous sayings is “There are no dumb questions.”, but I bet he hated when people asked “How do you talk about a mission to Uranus with a straight face?”
    Thank you, thank you, I’m here all week, don’t drink the milk.

  26. Richard B. Drumm

    I’m with you! I love the thing! I particularly like the blue-green color. It’s one of my favorite objects to spy in my 10″ scope. Very pretty!
    BTW, my youngest daughter’s name is Miranda too, so you’re in good company!
    Richard B. Drumm
    VP, CAS

  27. Folcrom

    Yes, Yes, very cool indeed.

    But, do we have to discuss “Rings around Ur-anus”?

    or should we be discussing “Roses”?

    Oh well, there’s the “inner” 12 year old boy in me again.


  28. These pics rock! Remember the voyager2 images?! Hah! What a difference 20 years makes….

  29. it’s a shame because in greek it sounds beautiful. the name comes from the greek ουρανός, pronounced oo ra NOS, which is the ancient deity for the sky, and is also the modern greek word for sky.

  30. jick

    This is way off-topic, but do you know that we Koreans frequently call our own country “urinara”? (Literally, “out nation”.)

    Unfortunately(?) that doesn’t sound like English “uranus.”


  31. Novelty

    Heh, Phil mentioned he is 6 Uranus months old. My question is by which moon of Uranus is he measuring the “months”. Is there a moon on Uranus that makes an orbit of the planet every 84 years?

  32. Nigel Depledge

    Toomanytribbles, I agree. I think of it as “Oo-rahn-os”, which avoids all the toilet humour altogether. Not that I have anything against toilet humour per se, it’s just that sometimes you want to discuss the planet without all the jokes.

    Mia, you beat me to it. Of course Phil should have mentioned Uranus’s axial tilt – it’s one of the most interesting things in the whole solar system. That must have been some impact!

    BTW, according to Bill Arnett (, Herschel named it Georgium Sidus (which translatesinto English as “planet George”, but sounds a bit more scholarly in the latin).

  33. MC

    > Carolyn Porco noted that Saturn’s rings are literally a few meters thicks [sic]

    Something here smells wrong to me. I’ve read over the years that Saturn’s rings are THIN (comparatively), but never THAT thin. This page ( cites various thicknesses around 1 KM or so. also quotes 1KM (, but maybe they were drunk. (Oo! sorry!) I might be misremembering, but I thought one of the shows Neil DeGrasse Tyson hosts said something about 1 KM also.

    Is Carolyn Porco’s figure based on more recent data? Or is this just a typo on BA’s part? (Or does he mean “1000” when he says “a few”?)

  34. Al

    ‘Way back when Voyager was approaching Uranus, the UK TV show Spitting Image ran a joke about the probe discovering a new satellite: Bumhole (pronounced B-yoom-hole-EE)…

  35. Irishman

    Novelty, Phil is partaking in some egregious abuse of language. If he is half a Uranus year old, and half a year is 6 months, then he is 6 Uranus months old.

  36. NGC 3314

    Nit – Voyager 2 delivered dark-side images of the Uranian rings, looking back at the Sun and getting a nice contrast between forward- and back-scattering views. The illumination was quite different from what we get now, and we have more wavelengths at our disposal, but this isn’t completely our first view of the dark side of the rings.

    (To Selena – yes, Neptune also has a ring system, which does make it seem suspiciously as if most giant planets have enough debris and moons to trap stuff long-term into ring systems.)

  37. Gary Ansorge

    Toomanytribbles: oo-ra-NOS!!! What a cool name for such a cool planet. I recall reading, years ago, that if oo-ra-NOS has a solid surface, the gravity there would only be about equal to one earth gravity. So we could float atmospheric probes quite readily, maybe even with people in them.

    Anyone up for a trip to the cool blue planet?

    GAry 7

  38. sirjonsnow

    Hmm, still no sign of Klingons.

  39. GaterNate

    “Doesn’t matter what we call it. Herschell called it George when he originally discovered it.”

    “Names don’t matter. Let’s look at the science here folks.”

    Of course nobody is suggesting the name is more important than the science. We can straight-up call it Planet Cornhole for all I care. However, most people tend to ignore that which they find unpleasent, and it’d be a shame if even several thousand years from now we’re still behind in our knowledge of Uranus because the general public found the name either silly or offensive.

    Imagine if when some future manned mission to one of the moons of Uranus is announced, and instead of awe and wonder and pride people just chuckle and change the channel. I wonder how NASA would deal with that PR nightmare. I know it’s stupid, but names are still important to some people. Look at how freaked out some people are over Pluto’s new classification.

    Looks like a lot of people pronounce it differently already. Pretty cool. I may also spell it “Urahn’Oose.” 😉

  40. All I was saying is that Dr. Phil has blogged (another) interesting blog about the rings but almost everyone is commenting on the name. I suspect (I must admit, I didn’t check) that virtually every time this planet id mentioned on this – or any other – blog, similar comments are posted.

    That’s fine. It’s amusing.

    I was just looking for some comment on the actual post itself.

  41. Stark


    More current data, as always, supplants older data. The current measurments for the A to D rings – these are the most visible ones – come up with a width for the complex of around 80-85 thousand Km. D ring is the closest the the planet and A is the furthest out. The thickness of each rings varys but they really are astonishingly thin. The C and B rings are both 5-10 meters thick and the A ring is 10-30 meteres thick. The D ring is pretty diffuse and I don’t know of any definitive measurments of it’s thickness.

    To put this in perspective… if the rings were a sheet of copier paper (thickness of .097mm) it would make a circle with a diameter of 873Km and a ring width of 275Km.

  42. BJN

    Hey, Phil was the one who said “butt”!

    The Keck images are impressive. Not sure what I’m seeing in terms of a composite with the Hubble image. Are the inner and outer rings from two images and that’s the source of the circular transition edge? I’m assuming the color image is dropped in for reference.

  43. Guy Who Doesn't Know Much About the Stars

    I just wanted to put in that if it’s a Greek word, it should be pronounced as the Greek pronounce it. oo-ra-NOS. I like that a lot. Better than the pee sounding one. sirjonsnow, thanks for mentioning the Klingons… I would have if you hadn’t.

  44. Got spam-binned yesterday, so I’ll rehash.

    @Guy Who Doesn’t Know Much About the Stars:
    the Indonesian pronounciation is oo-ra-NOOS, which is interestingly close to the Greek one (I’d hazard a guess that English is actually the outlier when it comes to Latinized pronounciation; English-speakers probably pronounce other languages the worst)

    Nobody has mentioned Douglas Adams yet?

  45. MC


    More recent data, gotcha. Thanks!

  46. Pat

    LaRoche limit – 2.44 planetary diameters at the same density, objects start to be pulled apart by differentials in the falling rate of their constituent parts. The larger your diameter as a planet, the wider (presumably) the zone in which you can have a stable ring. I’d guess that Saturn, being least dense and also high diameter, is the best candidate to have larger more permanent rings.

    Or at least that’s the extent of my memory of that particular bit of science…

  47. Mighty Favog

    Sorry I’m late, is anyone still reading this thread? About the “bright spot” in the rings–I see two bright spots in that image. The top one is apparently caused by looking through the thickest part of the rings. You can see it on both sides in the same position in the full image. The other one appears at the limb and seems to be the effect of brightness multiplying, the brightness of the ring added to the brightness of the planet. Below that there appears a slight variation that could just be noise. Anyone?

    You know, they discovered a new body recently. It apparently used to orbit Mars, but was somehow ripped away. It has tentatively been named “Homophobos” and it orbits VERY far from Uranus.

  48. Has anyone ever tried to figure out the motion of the sun as viewed from a point on Uranus’s surface (that is assuming you could see the sun through the clouds, and there was a surface to stand on, of course.)

    Try it as an intellectual exercise – imagine standing at the North Pole or the equator and plotting the sun’s position in the sky over a single Uranian year, bearing in mind the tilt of the planet’s orbit. The results might surprise you!

  49. Mark Martin


    Yes, analemas for other planets have been computed. Here’s a Quicktime of the analema for Uranus:

  50. Gary Ansorge

    Gee, I wonder if the Uranians would compute that as a direct statement from Eternity???

    GAry 7

  51. Petrolonfire

    @50. Mighty Favog Says:

    Sorry I’m late, is anyone still reading this thread?

    Er, yes. I just have. 😉

  52. Messier Tidy Upper

    @ 11. Selina Morse asked waay back on August 23rd, 2007 at 2:24 pm :

    A small questionette. Saturn and Uranus have rings, as, I believe, does Jupiter. Without looking it up in my text books, I’m not sure about Neptune.

    Yes – Neptune too has rings although they’re pretty faint and rather clumpy in nature with ring arcs around them. See :

    So, are rings regular companions of gas giants?

    They certainly are in *our* solar system. 😉

    I’d expect them to be common even ubiquitous also for most “cold Jupiter” or “cold Neptune” type gas giant planets around other stars. However, gas giants that are orbiting their suns closer than Mercury is to ours – the “Hot Jupiter” and “Hot Neptune” type gas giants may NOT have rings because :

    a) the nearby stars will melt any ice particles in the rings and the stellar winds may well blow dust particles away

    b) Hot Jupiter’s are thought to migrate in from where they formed further out in their systems and perhaps encounter a lot of other stuff that could well disturb existing or forming rings. They may well swallow entire terrestrial, earth-like planets as they encounter them starting to coalesce in the inner reaches of their planetary systems and you can only imagine that this would make it hard for rings to form and persist!


    c) the gravitational and tidal effects may well disturb the rings to the point where they can’t exist. Think I read this somewhere. Can’t quite recall where though. I’m not sure where the limit of “rings possible /rings not possible” are & I guess it would depend on the type of star the planet circles anyhow.

    And I didn’t think Saturn’s rings were smooth. What about the spokes in them? And isn’t the outermost ring only partial (an arc rather than a ring).

    Yes, Saturn’s rings have elevated spokes in them – think the BA has posted on those before – & also has “braids” and other odd structures. I spose “smooth” is a relative term …

    I suppose I’m really asking if rings like this are actually commonplace for larger planets. Until we have more evidence for other planetary systems, I believe we will only be hypothesising.

    I’d agree with that. Observation always trumps hypothesis – but then we’ve no reason to think rings won’t form around at least certain types of other planets and expecting our solar sytem to be unique in this regard is also unscientific unless backed up with evidence or so it appears to me.

    BTW. We also think there may be rings around Pluto and Saturn’s moon Rhea & I’ve read that Earth may one day have a “ring” of space junk which could be forming now … So yes, I’d say they must be pretty common features. Although I suspect few will be as specatacular and breath-takingly beautiful as Saturn’s rings. :-)


    PS. Hmm … Three years late to this party! Would this be a record for longest gap between a question being asked here & it getting answered I wonder?

    Hope you find this & get t read it somehow Selina Morse & its still interesing for folks here even if it is incredibly belated! 😉

  53. Environmentalist

    Keep Earth clean, it’s not Uranus.

  54. Hanna

    I just found out now so i came on this website to check it. You can look at it on google earth click this planet icon on the top then click sky then type in uranus and you should be able to see the ring. So I found ou n google earth

  55. reidh

    great Uranus joke subref.
    My $0.02 = Rename the anus. call it the anius,or the anous who would give a crop?

    You-Rain-Us, You’re-In-Us, You’re-On-Us, You’re-An-Us.

  56. karen

    If the planet is phonetically oo-ra- noos? Are the inhabitants still Urainian? Or Urusian?


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