Uranus Moons Miranda, Ariel, Umbriel, Titania & Oberon.

3488 · Jul 24, 2006

In responce to the Aproaching Iapetus thread (which I have found fascinating & Vogon13 has made it more so with his / her insights & knowledge, I would like to start something on the three different moons of Uranus. Please note that the Uranian system at the time was observed Pole On by the Voyager 2 spacecraft, as the tipped over Uranus system was close to a 'solstice'. This is really for those interested in Planetary Science. 1). Does anyone think that Miranda was smashed to pieces than reassembled over time?? Miranda similar in size to the Saturn moons Mimas & Enceladus & appears to be a love child of them both. Sizewise, Miranda is in between them. 2). I think not as the surface although jumbled does have a large primitive area & large ordered tectonic faults. Circular 'racetracks' due to former co-orbital moons smashing into Miranda or tidal heating in the remote past (cryovolcanics)? Cryovocanoes erupt slushy ice which then freezes solid, not molten rock as on Earth, Io, Venus, etc. 3). Does anyone think that Ariel has displayed evidence of Cryovolcanic activity? Widespread faulting is apparent. 4). What about the small channels running along the valley floors (liquid cut or cryovolcanic 'lava tubes')? 4). Both Ariel & Umbriel are very similar in size to the Saturn moons Tethys & Dione, yet all four are very different. Tethys & Umbriel I think are the least interesting as they seem to be nothing more than a pair of giant cratered iceballs. 5). Why is Umbriel the odd one out? Dark surface, cratered & unevolved. In size order largest first (diameter). Umbriel: 1,170 KM / 727 miles. Uranus system. Ariel: 1,158 KM / 719 miles. Uranus system. Dione: 1,120 KM / 696 miles. Saturn system. Tethys: 1,060 KM / 658 miles. Saturn system. Enceladus: 500 KM / 310 miles. Saturn system. Miranda: 472 KM / 293 mi <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

Miranda ice cliffs. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

Miranda, deep valleys & canyons on the limb. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

Ariel. Look at the eight o clock position. Looks almost like a geyser erupting!! <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

Ariel Canyons & Faults. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

Umbriel. The odd one out. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 24, 2006

A much better image of Umbriel (the previous one was pretty naff). Out of the five largest moons of Uranus, Umbriel was the least well seen by Voyager 2. Despite this, many craters were clearly seen Miranda was the best viewed. What does anyone make of the bright foreshortened ring at top? I think that it is a fresh impact crater, uncovering 'clean' ice. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

mikeemmert · Jul 24, 2006

<blockquote>In reply to:<hr />1). Does anyone think that Miranda was smashed to pieces than reassembled over time??<hr /></blockquote>Not me...<blockquote>In reply to:<hr />2). I think not as the surface although jumbled does have a large primitive area & large ordered tectonic faults. Circular 'racetracks' due to former co-orbital moons smashing into Miranda or tidal heating in the remote past (cryovolcanics)? <hr /></blockquote>Yes! That's it! I've thought that for a long time, since before the Voyager II flyby, in fact, although at that time I didn't have much evidence, mainly the Earth's moon, Triton and Pluto, Caloris Basin on Mercury, and Valhalla and Aesgard craters on Callisto. There was a lot of tectonic activity erasing evidence, which was disappointing, though fascinating in it's own right. The smaller moons appear to have preserved the record of co-orbital bombardment. Be careful about that word, "smashing", though. The difference in the racetracks and other craters is the speed of impact. A co-orbital will impact a moon at about the escape velocity of the moon, since it's at the same altitude (very slightly higher, since the solution to the three body problem is an equilateral triangle, which will always put the Lagrangian at a tiny bit higher altitude), which for Miranda is a mere 190 meters per second, slower than the cruising speed of a jet airplane. Forget blinding white-hot fireballs and resonating shock waves. It would look more like a controlled demolition. You seem to be really good at doing these pictures, and I would very much like to thank you for your work. Could you do me a favor? Could we see a closeup of the centers of the racetracks?

mikeemmert · Jul 24, 2006

Continuing on on my last post (since I am replying directly to this picture), we were left with two large mound of rubble. Miranda is just big enoungh to squeeze itself into a sphere, so the rubble piles would slowly collapse. The pressure from that collapse apparently raised a big block of material, which is shown protruding in the photo you provided.

mikeemmert · Jul 24, 2006

Hmpf...That's a really interesting picture! Actually, I didn't look at it until after I had written the other two replies... Does that look to anybody else like a large body squeezing into Miranda's crust, depressing it? Like maybe placing (not dropping or hurling) a lead ball into a big mess of silly putty?

3488 · Jul 25, 2006

I hope that the below image of Miranda helps. I have done my best since I am limited to 100 KB (I could have done much better without this limitation). I have enlarged & enhanced the central portion of the 'racetrack' on the leading hemisphere on Miranda. It was pretty handy that it was on the terminator, so the sunlight was shining on it at a shallow angle, bringing out the fine detail, hills & ridges, etc, on the Minus 215 Celsius / 58 Kelvin icy landscape. The trailing one was too blurred to do much with, but the leading one was nice & sharp. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

alokmohan · Jul 25, 2006

Reminds me of Miranda in Shakespears drama drama.Tempest.http://en.wikipedia.org/wiki/Miranda_(Shakespeare)

3488 · Jul 25, 2006

Hi, I understand that the moons of Uranus were named after characters in the literature of William Shakespear (Bill Shakespear in the USA & Canada) & Alexander Pope. William Herschel, who discovered Uranus itself, also discovered Titania & Oberon (I think) & started this trend. It has carried on since. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

How about this one of the Chevron on Miranda? <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

Miranda. Old cratered terrain & portion of 'racetrack'. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

Large canyons on Ariel. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

Varied terrain on Ariel. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

alokmohan · Jul 25, 2006

http://home.case.edu/~sjr16/uranus_moons.html.All the moons of Uranus are from Shakespears drama.

3488 · Jul 25, 2006

For some reason I thought that Umbriel came from one of Alexander Pope's works. Anyway, I have posted an image of the Neptune moon Proteus (about 400 KM / 249 miles diameter). Proteus has two large depressions, but they are in the polar regions. Do ypou think that Proteus may have had co--orbitals & if so, would the impact sites, not be closer to the equator? <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

Enlargement of the Southern Hemisphere Depression on the Neptune moon Proteus. mikeemert, do you think that the Pluto moon Charon will display post co-orbital impact scars, when New Horizons arrive? <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 25, 2006

Uranus moon Puck (154 KM / 96 miles diameter). The large crater to the top right, a co-orbital scar?? <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

mikeemmert · Jul 25, 2006

<blockquote>In reply to:<hr />Umbriel - the odd one out.<blockquote>In reply to:<hr /> Hi, I have decided to refer to this image of Umbriel rather than the larger one. There is better contrast here, which brings out the second Lagrange impact site. It's still kind of hard to see. Notice at about the 8:00 o'clock position, a little south of the equator (remember, this is a pole-on shot from the south so the equator is on the rim). There is a large, indistinct circular feature there, about 40%- 45% the diameter of Umbriel. Plus, there is the bright feature at the top of the image. But notice that it is surrounded by something that looks like an ejecta blanket and is about the same size as the other conjectured impact zone. Escape velocity on Umbriel is 520 meters per second, so that's how fast a Lagrangian will impact. A comet, on the other hand, will be travelling at several kilometers per second. It will be falling towards or away from the Sun, as well as picking up about 5 or 6 km/sec from Uranus' gravity. Ejecta will spread across the entire moon, rather than being confined as we see. Why is there a bright feature on the top impact site and not the 8:00 one? I don't know. Let me comment on Ariel on this post. I have no idea what the large canyon represents. I have some vague idea of tectonism or a lava (water at those temperatures) flow. I have put Uranus' large moons in some of my GravitySimulator models of the capture of Triton, to fill in for "Galilean" moons of Neptune that Triton ate. I noticed that these don't follow the Titius-Bode spacing very well. Instead, Ariel and Umbriel are a little closer together, then there is a gap and then Titania and Oberon are fairly close together. Ariel and Umbriel approach each other as close as 75,000 km. Thus, there is probably a bunch of</blockquote></blockquote>

mikeemmert · Jul 25, 2006

Gee, 3488, thanks for posting the closeup. To tell the truth, whatever it was I was looking for (a whirlpool, maybe?), I didn't see it. Sorry, I know that was a lot of work. My bad... <img src="/images/icons/frown.gif" />

3488 · Jul 26, 2006

I think that all of the Uranus moons are inactive now. The possible exception is Titania. http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=539786&page=1&view=collapsed&sb=5&o=0&fpart= <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 26, 2006

This diagram shows albedo variations on the Uranus moon Umbriel. This image is an adaptation of a figure from an article by Paul Helfenstein, Peter C.Thomas and Joseph Veverka published in the March 23, 1989 issue of Nature. The color image is an albedo map of Umbriel after shading correction and contrast enhancement. Dark regions are represented as red and bright regions are represented as blue. The two white regions are bright ejecta from two fresh craters. In the article the authors suggested that the dark areas are the result of an internally driven resurfacing event early in Umbriel's history involving darker material. Similar ice volcanism is also seen on Miranda, Ariel, and possibly on Oberon. They also state that the limited data also hint that the darker regions are lower in elevation. (Courtesy A.Tayfun Oner) <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

Uranus Moons Miranda, Ariel, Umbriel, Titania & Oberon.

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