Uranus: A family portrait (II)

We are a large and literate family, with members of all shapes and sizes.

My dad and some of my siblings. From left to right: Puck, Miranda, Ariel, Umbriel, Titania and Oberon. Sizes are scaled, distances aren't. Credit: Vsb83 based on NASA images (via Wikimedia Commons)

Have I told you we are a highly educated family? We all love to read, especially works by Earthling writers William Shakespeare and Alexander Pope. As a matter of fact, we all (except our Dad) got our names from characters in their books... Not that I have anything against the mythological names the majority of our relatives hold, but I think that ours are more original.

We are a big lot... Twenty-seven, to be precise, of all sizes and shapes. Or maybe more. We are very protective with our smallest siblings, so I apologize for not putting them into the limelight.

Round and proud

The biggest ones, on the other hand, love to be the centre of your attention. Granted, they are not so irritating like some of our cousins (I won't say names), who are always boasting about their potential for hosting life... Still, they believe they are special, because of their rounded shapes. (Roundness is overrated, if you ask me!) Even so, they all worship our father, and only have eyes for him, always pointing the same face towards Daddy.

Titania and Oberon are the largest. They are almost twins, less than one half the size of our aunt Earth's Moon. You would say that's not such a big deal, but in fact, you can observe them from your planet even with certain amateur telescopes. They are very proud of that!

Oberon (left) and Titania (right) are nearly twins in size, but have very different looks. Images taken by the Voyager 2 probe. Credit: NASA

Next is Umbriel. Three times smaller than the Moon, he is hard to observe due to its dark surface that barely reflects light. The reason of his shyness is all the craters in his surface. I wonder why he feels so ashamed (Oberon has even more craters, and he doesn't seem to care). He has many nice features too, like a bright ring 140 kilometers wide near the Equator that makes him look really cute.

Ariel is the opposite: He likes to shine. Well, he's the youngest of the group, with only small craters scattered on his surface, so you can allow him to be a bit foolish.

And the fifth one is Miranda. Contrary to the rest, who are a mix of rock and ice, she's mostly made of ice, with a surface displaying canyons and valleys on some parts, and heavily cratered on other parts. Some say it is as though she was made from pieces of many different objects, like a sort of Frankenstein's monster... You would think she would be annoyed by the comparison, but on the contrary, she enjoys puzzling you Earthlings.

Umbriel (left) with its puzzling bright ring at the top, a close view of Ariel (centre), and the amazing surface of Miranda (right). Images taken by the Voyager 2 probe. Credit: NASA

Living among the Rings

Let me know introduce my own bunch. We call ourselves "the Inner Moons". While our biggest siblings like to keep some distance (between one third and twice the separation between auntie Earth and her Moon, to be precise), we are quite attached to Daddy. There is also much more fun down here, because of the rings. We love running among them, playing and continuously teasing each other in a sort of chaotic harmony.

Puck is the largest, but there's not much more I can tell you about him. He would like to be considered one of the Large Moons (despite they not paying any attention to him), and does not hang around with us too much. He stays in a relatively large orbit (only little Mab is closer to Miranda than him), moving around Uranus in less than one Earth day. He does not chat even with me, and we are not that far apart!

I prefer to spend my time with Belinda and the others: Rosalind, Bianca, Cressida, Desdemona, Juliet and Portia, our leader. We are all very alike, dark and made of carbon, and have similar tastes and hobbies. However, sometimes there is conflict between Desdemona and Cressida or Juliet; I fear that they will collide one day or another. This is sometimes annoying for the rest of us, except for our smallest brother, Cupid (just about 18 kilometers wide); there are very few things that can actually perturb him.

We also take care of the rings, especially Cordelia and Ophelia. Also Mab likes to give a hand. It is hard work, to keep all that dust and tiny rock organized! They are like sheep that need direction.

Location of all the Inner Moons within the Rings of Uranus. Credit: Cartwright et al. (2021), modified from Showalter (2020)

The black sheep

And finally, there are our adopted siblings, also called "the Irregular Moons": They orbit much farther than Oberon, and were attracted by our Dad long time ago. Maybe because of that, they like to do things their own way. As a matter of fact, they are all quite eccentric!

Margaret is the only one that moves like the rest of us, in the same direction our father spins. But don't be mistaken: This does not mean that Margaret is "normal" at all. Her orbit is like a slide (tilted nearly sixty degrees!) and once, in 2010, she simply changed the size of it, making it even more elongated, just for the fun of it. She is very independent, and keeps saying that she won't stay with us for long.

The remaining eight prefer to go around Daddy in the opposite direction –something you could call retrograde. If you ask me, that's just for the sake of contradicting. This bunch are not as united as my own, or even our biggest siblings. In fact, they are split into two groups, clearly separated from each other: Francisco, Caliban, Stephano and Trinculo on one side, and Sycorax, Setebos, Prospero and Ferdinand on the other. Being by far the largest (his size places him in-between Portia and Puck), Sycorax could be consider the leader of the latter. But in truth, each one has their own (inclined and elliptical) way, and I wouldn't put my hand in the fire that they do not quarrel in the future.

Orbits of some of Uranus' irregular moons. The light green dot at the centre indicates the position of the planet, and the curves and moving dots around it display the orbits of Sycorax (pink), Francisco (cyan), Caliban (yellow), Stephano (red) and Trinculo (dark green). Credit: Phoenix777 using NASA data (via Wikimedia Commons)

So this is us, the Uranian family. Despite all ups and downs, we have been together for billions of years, and we will continue to do so –at least, the majority of us. Don't you think it is about time to pay us another visit? It's been decades since Voyager 2 called in in the 80's!