Active worlds in our Solar System.

[3488]

H20universe, has compiled a fascinating list on another thread & I thought this topic merits<br />its own thread.<br /><br />Very interesting post by H20universe.<br /><br />I have also copied H20universe's interesting comments & list. I have not<br />changed any comments in any way, hence the link above.<br /><br /><font color="yellow"> Hi all, <br />Numerous new bodies are fine but if they are dead balls, they are of limited interest. <br />So, let's look now at the bodies known to have "activity" (as opposed to geological death): Volcanism, <br />Cryovolcanism, Ice convection or liquid water layers, Liquid core, Current resurfacing processes, <br />Evaporation/condensation cycles <br /><br />RECENT DISCOVERIES OF ACTIVITY ON SOLAR SYSTEM BODIES IN THE TWO PREVIOUS DECADES <br />Venus, Mars, Io and the four giants were already evidenced as “active†before 1987 <br />Since then, I come to 11(*) to 15 additional bodies with indication of activity, starting from Triton’s fly-by by Voyager: <br /><br />Triton (1989) (cryovolcanism) <br />Europa (1997) (water or slush layers) <br />Ganymede (2000) (water or slush layers) <br />Callisto (2001) (water or slush layer) <br />Pluto (2002) (atmospheric cycle) <br />Ceres (TBC) (2003) (differentiation evidenced) (frost cycle?) <br />Titan (2005) (atmospheric cycles, rains, lakes, cryovolcano) <br />Eris (TBC) (2005) (methane cycle) <br />Enceladus (2006) (resurfacing, vents) <br />Dione (TBC) (2007) (vents ?) <br />Mercury (2007) (molten core) <br />Quaoar (2007) (cristalline ice) <br />2003EL61 (2007) (cristalline ice) <br />Charon (2007) (cristalline ice) <br />Iapetus (2007) (surface substance transfers by thermal segregation)(currently? TBC) <br /><br />I am aware this list is subjective. Any comment or correction? <br /><br />(*) the 15-11=4 ones with reservation: Ceres, Eris, Dio</font> <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[vogon13]

I'll have to check a reference book, but I believe flow features of unknown age were spotted on Ariel, and I seem to recall a graben on Titania.<br /><br />This is my own take, but the darkening on Umbriel might be resultant from outgassing from Ariel. Implying, perhaps, a bit more of an active Ariel than is generally supposed.<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[l3p3r]

Isn't the atmospheric cycle on pluto due to the changing distance from the sun and subsequent sublimation of frozen surface dioxide? Does that classify as 'not geologically dead'? <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

Seems it is geological.

 

[l3p3r]

oops didn't read the first post properly, the original list did include evaporation/condensation <br /><br />but - I don't think that counts as geological activity, does it?! <div class="Discussion_UserSignature"> </div>

 

[3488]

I would like to say a huge Thank You Vogon.<br /><br />Your post reflects very much my own conclusions. Good to know that I am barking up the <br />correct tree. <br /><br />You are correct, in that the darkening of Umbriel IMO IS due to out gassings & dust escaping Ariel.<br /><br />Also you are correct about the flows on Ariel. <br /><br />IMO, they are quite young on the geological timescale. The canyons themselves, show <br />only very little<br />impact cratering at Voyager 2 image resolution<br />(approx 2 KM) & IMO, Voyager 2's images are more than good enough to confirm their <br />relative youth (seeing as other areas on Ariel are heavily cratered). True, thare are<br />some craters in some of the canyons, but not nearly as densley cratered as many other areas.<br /><br />Also some of these canyons, cut through the cratered terrain, also implying a younger age,<br />as well as the narrow rilles in many of these canyons, appear undamaged, not interrupted by<br />subsequent impacts.<br /><br />Also on the terminator, there is a smoothish area ,with what appears to be flow like features, <br />also very crater free.<br /><br />Another thing, is that Ariel appears to be relatively dense, about 1.56g/cm3, (a little denser <br />than Saturn's Dione @ 1.43g/cm3) implying<br />IIRC a roughly 50% rock / ice mixture & would not surprise me if Ariel is differentiated.<br /><br />Yes Titania does have a huge Graben system, one section of wall appears very bright. <br />Frost maybe, perhaps outgassing, tenuous atmosphere?? <br /><br />There are also softened surface features. Titania is also reasonably dense @ 1.7g/cm3. <br />Titania too may be differentiated.<br /><br />Oberon, too appears to not have had an inactive life either. Many impact craters have <br />darkened floors, suggesting cryovolcanic flooding, darker ares, as well as some <br />surface feature sofening.<br /><br />Miranda, may well be the most visually dramatic, but I suspect that Miranda is no longer active.<br /><br />Andrew <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[3488]

Hi l3p3r,<br /><br />Technically no, that does not constitue geological activity. However, frost migration<br />& atmospheric inflation / contraction does constitute an active world, atmospherically speaking.<br /><br />There appears to be cryovolcanism on Charon, though not yet 100% evidenced & there<br />is a chance that Pluto too is cryovolcanically active, but is maybe harder to spot, as Pluto's <br />surface is chemically enriched. The same is likely to be true of Eris.<br /><br />Obviously with Pluto & Charon we may have to awauit New Horizons arrival, unless <br />Earth / space based observations can confirm prior to New Horizons arrival.<br /><br />In many ways I hope so, because if we can confirm activity on one or the either or both,<br />we can optimeze New Horizons encounter to maximum effect.<br /><br />Hi all,<br /><br /> Interesting article on Io's atmosphere.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

Hi Andrew,<br /><br />thanks for developping this subject!<br />My aim, beyond the dry statistics, was to highlight the accelerating pace of our knowledge, and how exciting these times are.<br /><br />Re Ariel, Titania, Oberon: the case Vogon and you are making is highly convincing for past activity. But is it evidenced as "very recent" (i.e. recent enough to think it may occur again)?<br /><br />Best regards.

 

[h2ouniverse]

In reply to<br />---------<br />but - I don't think that counts as geological activity, does it?! <br />--------<br /><br />from pure geological point of view (or in that case "hadeological"), you are right. But with a cycling comes inevitably some chemical reshuflling, a climate, changes in surface aspect.<br />Qualifies as "active" for me in the broader sense. This means seasons and a climate. There is certainly an arbitrary limit since any body with ellîptical orbit will experience some seasonal effect and few atoms vaporized should not count. In the case of Pluto, the phenomenon is large enough to act on starlight deviation as seen from Earth so...<br /><br />Btw, at such cold temperatures there is huge potential for physical cycles (phase transition) for many species. Chemistry at cold temperatures looks fascinating.

 

[3488]

Hi Joel,<br /><br />That is exactly what Vogon & myself are trying to evidence. <br /><br />Because Voyager 2 was travelling very fast & could not stay, it is very difficult, if nigh well <br />impossible to tell if activity is ongoing.<br /><br />However, Voyager 2 did succeed in showing very well indeed, that face of Ariel, displaying<br />varying cratering units & non impact related geology, that happened not so very long ago IMO.<br /><br />Smoothish floored canyons that can be followed for long distances, without being<br />interrupted by cratering (unlike the Voyager Mountains on Iapetus, which have been <br />greatly damaged by subsequent cratering), the darkening of Umbriel from <br />outgassings from Ariel?<br /><br />Plus one area that does look very youthful, so youthful, I do wonder if it is a site of ongoing <br />activity?<br /><br />Also some craters, appear to be on now frozen ice plumes (Diapirs), which means <br />IMO, the ice is not just cleaner because it is recently exposed, but because the ice <br />is of a crystalline nature in that area (I think I have found similar evidence on Dione too,<br />thanks to one of FranOntanaya's post's, who alerted me to it on the Cassini thread).<br /><br />Very interesting stuff.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

"appear to be on now frozen ice plumes (Diapirs), "<br /><br />If this leads to think there are water or slush layers underground that is great news.<br /><br />Would mean both diapirs and layers.<br /><br />(sorry, I coul dnot resist)

 

[3488]

Hi Joel, <br /><br />That IS exactly what I think. <img src="/images/icons/laugh.gif" /><br /><br />I think Ariel is a very differentiated body, WITH ice layers in the crust.<br /><br />Highly probable with Titania too.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

Also:<br />"darkening of Umbriel from <br />outgassings from Ariel? "<br />While I am still on pathetic puns, I must note that the whiteness of Ariel makes Umbra on Umbriel.<br /><br />So that means that there might be hot points on Ariel, that make Umbriel dirtier.. Hmm No way, they say "Using Hotpoint and Ariel together you'll get the best washing results":<br />http://ariel.co.uk/hotpoint.html<br /><br />Joke apart, I hope you will succeed in adding Uranian moons to the list.<br /><br />Regards<br />Joel

 

[3488]

Ha, blooming ha, yes it does sound like a commercial for washing powder. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/tongue.gif" /><br /><br />I hope that I will succeed in finding the evidence. Not easy, but doable I think & hope.<br /><br />I will keep you in the loop Joel, no problem at all with that.<br /><br />I will need some Hubble & / or Spitzer observations, to search for spectral / thermal anomalies <br />& even see if Ariel & / or Titania are leaving behing very tenuous rings (very long exposures required)<br />around Uranus (crying bloody shame that New Horizons 2 was cancelled, we would have <br />had a Uranus encounter in 2014). <img src="/images/icons/frown.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

I still admire that you can achieve that from Hubble. But if you can, while you are there, could you please ask them to take more pictures of Ceres?<br /><br />Their movie last time had only... 6 pictures!! A pity for it seems that they might detect surface color/albedo variations during the Cererian day (i think there are some on their pictures but is it just my imagination?). Especially close to the "white" features. Looks doable given the resolution they achieved (50km-pixels plus postprocessing) I am so surprised that over 2 days they could take only 6 picutres of a mag 7 object!<br /><br />

 

[3488]

I will ask them, of course, I too am interested in 1 Ceres (otherwise I would not have <br />bothered to take part in the campaign to get the DAWN mission approved & reinstated).<br /><br />We need to confirm if those observations were just six images, or if they are just six images <br />from a series???<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

You are right. May be they have more. But then, why having published an animation with only 6? (and not evenly spaced vs time btw)

 

[h2ouniverse]

Actually I was refering to this release:<br />http://hubblesite.org/newscenter/archive/releases/2005/27/image/e/<br /><br />But in the same time they said they shot 267 images over one rotation...<br /><br />"Hubble snapped 267 images of Ceres as it watched the asteroid make more than one rotation. By observing the asteroid during a full rotation, astronomers confirmed that Ceres has a nearly round body like Earth's. Ceres' shape suggests that its interior is layered like those of terrestrial planets such as Earth. Ceres may have a rocky inner core, an icy mantle, and a thin, dusty outer crust inferred from its density and rotation rate. <br />Astronomers enhanced the contrast in these images to bring out important features on Ceres' surface. The observations were made in visible and in ultraviolet light. Hubble took the snapshots between December 2003 and January 2004."<br />"<br /><br />Actually that went at least from Dec 30th to Jan24th.<br />So it is not clear whether they really have a full rotation with a good time resolution.<br />

 

[3488]

Good point, it does seem strange. I think we have to remember that the Hubble is<br />booked up by many differing interests. I am pleased though Hubble succeeded in getting good <br />Uranus ring plane observations, etc.<br /><br />Having said that, now we know DAWN has launched successfully & is on a perfect trajectory, <br />Ion engine working well too, I would expect many further observations of 1 Ceres & 4 Vesta<br />pre arrival, as new observations will <br />help optimize DAWN's orbital tour at both.<br /><br />That's my take of it anyway.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

That would be good also if, in addition to enhanced colouring, they also published real colour views (human-eye). I guess they would look quite grey but we should not create undue expectations in the public.<br /><br />This being said, I still get the impression that between view Jan 23rd, 23:40 and Jan 24th 0:15; the regions close to the whitish spot that ends in the middle become less bluish and more reddish at Cererian noon than in Cererian morning. (South East at 23:80 , South central at 0:15).<br />

 

[3488]

Do you think that is frost burning off, or sunlight being polarized through ice??<br /><br />Anyway, I am signing off now as it is getting late.<br /><br />Good night everyone.<br /><br />I will be back tomorrow (as everyone vows never to look at SDC again, after that threat). <img src="/images/icons/laugh.gif" /><br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"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".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[h2ouniverse]

Hi Andrew,<br /><br />About frost or clouds: yes, I was wondering.<br /><br />Btw, I fell on that:<br /><br />http://www.keckobservatory.org/article.php?id=93<br />Excerpt:<br />"Additional spatially resolved spectroscopic observations are needed to investigate further the properties of Ceres surface. Such programs will help in the preparation of the NASA DAWN mission, which will reach Ceres in 2015 and explore, from orbit, the properties of this intriguing solar system body. The team is currently planning complementary observations of Ceres during its next opposition in November 2007, using a suite of adaptive optics instruments at the Very Large Telescope of the European Southern Observatory in Chile."<br /><br />Let's hope they find something!<br /><br />Cheers

 

[robnissen]

More evidence that Mars is active -- dormant, but not extinct, volcanoes:<br /><br />http://www.space.com/scienceastronomy/071017-mars-magma.html

 

[h2ouniverse]

Great news.<br /><br />To me Mars was already in the active category anyway, with the dynamism of the polar caps, the dust storms and the chemistry at play.<br /><br />Ancient volcanoes: another subjective constancy down.<br /><br />Regards

 

[h2ouniverse]

Hi Andrew,<br /><br />follow up to "Do you think that is frost burning off, or sunlight being polarized through ice?? "<br /><br />Unfortunately it seems spectro observations have failed to detect water ice for now.<br /><br />But I get the impression that they do not have reliable mesurements on the limb and on poles.<br />Temperature can reach 239K at equator, but if I extrapolate (even assuming albedo of 0.11) to the poles, max temperatures at Cerian noon fall below 170K for latitudes higher than about 70° (depends on season) and closer to 130K beyond 80°.<br />The poles should be always very cold, and trap frost.<br />Spin axis Tilt = just 4° to 5° vs orbit plane. = /> surface conditions at Ceres poles should be comparable to icy moons in mid-solar system.<br /><br />Best regards.