Uranus

jaxtraw · Aug 11, 2007

"The problem is, as that as we find more, that list will balloon" I think this is the conceptual problem. There is a fundamental assumption among anti-Pluvians <img src="/images/icons/smile.gif" /> that the list of planets should be short in number. This is entirely an historical anachronism based on a primitive concept of a solar system consisting of a star, a small number of planets in quasi-circular orbits, and some garbage-- and that's based largely on the really primitive idea of the entire heavens consisting of the sun, moon, some comets and a few wandering lights. The solar system is a complex place full of a myriad bodies and those who determinedly rejected the smaller ice planets with the bizarre ad-hoc "cleared its orbit" criterion seem determined to keep it simple so far as one can tell so they can recite a list of "The Planets" and keep to a simple mental model that looks like a 17th century orrery. The solar system consists of a star, four major gas giants and a whirling mass of other worlds composed from various proportions of rock and ices. But we ended up with a definition that (not only ludicrously only applies to our own little stellar system) but lumps the utterly dissimilar Jupiter and Mercury into the same classification, just apparently to keep things simple and keep our own tidgy planet at the "top table". The solar system is a complex place. The list, naturally, balloons.

mithridates · Aug 12, 2007

That's a really good way to phrase it. So good, in fact that I took the liberty of quoting you on another board that a few of us run in Korea: http://forums.galbijim.com/index.php?showtopic=1846&st=0&gopid=12341&#entry12341 <div class="Discussion_UserSignature"> ----- http://mithridates.blogspot.com </div>

3488 · Aug 12, 2007

Thats a great board mithridates. Thanks for sharing it. I like that animation of 2003 EL61. Very cool. Andrew Brown. <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>

jaxtraw · Aug 12, 2007

Immortality is mine <img src="/images/icons/smile.gif" /> Thanks for the compliment. Perhaps I was a little strident, but I'm a bit of a fan of the ice dwarves. I suspect we're going to find an active surface on Ceres, when Dawn finally saunters over there, for instance.

mithridates · Aug 13, 2007

Thanks. It's not related to space at all but I always try to bring up the subject on other boards as well since almost everybody is interested in space to a certain extent - at the very least everybody enjoys looking at the Moon and the stars, and most like hearing somebody interested in the subject talk about it every once in a while even if it's an unrelated subject. <div class="Discussion_UserSignature"> ----- http://mithridates.blogspot.com </div>

3488 · Aug 13, 2007

Do not forget jaxtraw. I too am very fond of the ice dwarves too. They should have their own category. The planet Uranus BTW is orbited by a family of interesting icy moons. I think 1 Ceres will be very interesting when DAWN arrives. I think that we will not be disappointed. I will come back to this point tomorrow. Good Night every one. Andrew Brown. <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>

brellis · Aug 13, 2007

I started a thread on the Ring Plane Crossing which occurs 16 August 2007 - this Thursday! <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

alokmohan · Aug 14, 2007

Dont fail to inform result in due time.

3488 · Aug 14, 2007

Do not worry alokmohan, I will be watching for the latest developments also. brellis & myself will post interesting developments. Andrew Brown. <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>

h2ouniverse · Aug 14, 2007

Count me in the camp of the ice dwarves too! Personnally, I think the appellation "dwarf planet" is excellent. I suspect not all of them realized that once accepted, this has triggered a de facto twilight about planethood, and this is a good thing. Because in the long run, semantic is all. A dwarf person is a person. A dwarf star is a star. So a dwarf planet, whichever resolution is passed by IAU, will be considered a planet, or a kind of... The laymen will recite a short list of 8 bodies (+ may be others outside, given the likelihood of captured exoplanets on weird, far orbits). The more educated in astronomy will be able to recite a list of tens of bodies. Fine!

3488 · Aug 14, 2007

Hi Joel, Whats your take on Sedna??? Andrew Brown. <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>

h2ouniverse · Aug 14, 2007

Hi Andrew. To me Sedna is probably a dwarf. Unless not "in hydrostatic equilibrium" which is unlikely. This being said the size of TNOs has been so dynamic... I understand that they are not in a hurry for the classification of nanoplanethood. I think that until we can get reliable size and approximate shape by visual and/or IR observation, we should be cautious. In the case of Sedna the size is known with enough margin. But the shape? As far as origin is concerned I do not know. Given the relatively low perihelion for an OOC-object, I would bet on solar origin, with formation in this region. But the other three options are open: 1) formed far closer to ice limit, then ejected to the outskirts (but requires two big delta-Vs, one for aphelion, one for perihelion (*)) 2) extrasolar, pre-existing the Sun, caught in the Solar primordial nebula, and surviving its spiraling 3) extrasolar, captured by Solar System along Sun's galactical path Regards. (*) unless a bigger planet lurks (or lurked) out there, exchanging Sedna's eccentricity with inclination through a Kozai mechanism. Neptune is too far (space-wise and period-wise) to do that.

brellis · Aug 14, 2007

Emily Lakdawalla's blog on the May 2007 ring plane crossing <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

3488 · Aug 14, 2007

Thanks brellis. Uranus approaching equinox from The Keck Observatory. Actual Uranus Equinox: Friday 7th December 2007. Keck's Changing View of Uranus From 2001 to 2004, Uranus's motion around the Sun has changed its orientation as seen from Earth in these images taken through Keck II's K prime filter. The four images also show how the Adaptive Optics system has improved over time. The same astronomers have continued to study Uranus from Keck II as its equinox approaches. Credit: Imke de Pater, Seran Gibbard, Heidi Hammel / W. M. Keck Observatory. Andrew Brown. <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 · Aug 14, 2007

Uranus has all moons named from Shakespeare.3488 owns Shakespear,as both are British.

3488 · Aug 14, 2007

That is a wonderful compliment alokmohan. You can call me Andrew, we two are certainly on first name terms & have been for a long time now. I only wish I had even half of William Shakepeare's intelligence & wit & yours for that matter alokmohan. Yes, the Uranus moons are all Shakespearean characters & are the only large solar system bodies, not named from classic world mythologies, but from British Literature. Once again, thank you very much alokmohan. Andrew Brown. <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>

ihwip · Aug 14, 2007

I think we need to send a probe to Uranus as soon as possible. There are extremely important things that we could learn from just the magnetic field. For instance...the interaction between the solar plane and the magnetic field, the bizarre rotation and the magnet field. How the satellites are effected. There is so much science in this one planet that it is a shame we haven't sent anything there. I think the time is coming soon though.

3488 · Aug 14, 2007

Hi IHWIP, Not just that, but the geology & history of the moons are compelling reasons, as well as the weird weather of Uranus itself. A Galileo entry probe would be of much value (this time camera equipped too). Both the Uranus & Neptune systems are really in need of further research & both require orbiters, like Galileo or Cassini. Below. Uranus & Neptune in August 2003 as seen from the Hubble Space Telescope. Andrew Brown. <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>

robnissen · Aug 14, 2007

While I too would like to see a mission to Uranus, I question (although I do not know), if we have the current technology for an orbital mission to Uranus in any kind of reasonable time period. It is my understanding (please correct me if I'm wrong), that if Cassini had been going much faster on its mission to Saturn, that it would have been going too fast to be captured by Saturn, even with using its engine to slow down as much as it could. If that is the case, then we would have to have a much slower mission to Uranus, which is already much farther away, in order for Uranus' lower gravity to be able to capture the ship. Does anyone have any idea on what speed a Cassini-sized ship would need to be traveling to be captured by Uranus. My guess is that the speed the ship would need to be going to be captured by Uranus would make the mission length to Uranus on the order of 40 years (Again this is a WAG on my part). I don't believe NASA would fund such a mission.

3488 · Aug 14, 2007

Very true anvel. I think that the rings would have remained undiscovered until Voyager 2. Visually Uranus itself was a huge disappointment, after Jupiter & even Saturn (mostly for the rings) the light blue featureless haze obscuring any storm systems, etc. Also the encounter was not an easy one. The closest approach to Uranus & the moons all occured more or less together, as the system is tipped over & at the time, close to a solstice, not to mention Voyager 2 was also on course for Neptune. However, we got good images of all five of the main moons, very good images of Ariel & some really good close shots of Miranda. The moons were the real show stealers, who would have expected Miranda & Ariel to be so highly evolved???? Even Titania & Oberon appeared to have undergone some cryovolcanism in the remote past. The rings as expected were more complicated than was deemed possible from crappy low resolution Earth based observations. I certainly was part of the campaign to get New Horizons 1 & 2 launched. As we know, New Horizons (1) is now safely on route to Pluto after accomplishing an amazing Jupiter encounter back in February (a mission in itself) but New Horizons 2 was cancelled, due to funding & lack of available Plutonium for the RTG. NH2 was to have rendezvoused with Jupiter & Uranus in 2014, on route to the Kuiper Belt. Despite these set backs, the HST has kept a beady eye on this large outer planet & the weather at Uranus is getting more exciting as the equinox draws nearer this December. Lets hope Hubble does not foul up. Below. Storms raging in the Uranian atmosphere. August 2003. Hubble Space Telescope. Andrew Brown. <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 · Aug 14, 2007

Very true RobNissen. Unfortunately a Uranus orbiter could not approach very quickly. That is true about Cassini BTW. had Cassini approached Saturn as fast as the Voyagers or Pioneer 11, then yes, Cassini would not have lost enough deceleration to enable capture. We have the same problem here. Having said that, with modern, low weight composites & alloys, the Uranus orbiter need not be as massive as Cassini, so a large retrorocket may still be enough. However the time scale of 40 years for the journey, may not be that far off the mark. You are probably correct, NASA probably would not fund that. With Neptune, it would be even worse. Worth bearing in mind is that both Uranus & Neptune are also orbiting the Sun at lower speeds than Saturn as well. So not only braking into orbit around smaller planets with weaker gravitaional fields, but also slower moving planets too. But I am not a rocket scientist, so I could be wrong. Below Uranus in Natural Colour. August 2003. Hubble Space Telescope. Andrew Brown. <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>

jaxtraw · Aug 14, 2007

Rob, this is why I would argue we need to get back on developing nuclear rockets. Current chemical designs simply don't have enough oomph. As we've seen with New Horizons and as you've just highlighted, it's not so much a problem starting out fast enough from Earth; it's a problem of slowing down when you get there! I think personally that small nuclear rockets are the way to go to solve that problem. I'd like to see a probe get to the outer solar system in a reasonable amount of time and then be able to stop and pay a reasonable visit, instead of whizzing by. New Horizons' visit is going to be heartbreakingly brief. It'll be our first visit to such a world, and we'll no doubt see much that will have people saying "if only we could get another/closer look at that!"

3488 · Aug 14, 2007

Hi jaxtraw. I agree with you 100%. With the New Horizons Pluto system encounter, you can bet just that. Nuclear rockets really is the only way to be able to pull off a decent Uranus / Neptune orbiter mission in a reasonable timeframe. True, it could be done perhaps with a double staged solid retromotor (like the Boeing IUS, but in reverse), with perhaps aerobraking, but for one that is risky & two, the launch vehicle to launch that would have to be huge & thus increase costs & complexities. However a Voyager / New Horizons type encounter for both will still reveal much new information. Andrew Brown. <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>

brellis · Aug 14, 2007

The Voyagers are apparently good for 50 years, proving that it's worthwhile to do as much as possible to extend/prolong the useful lifetime of a craft headed to the outer planets. IIRC, the Voyagers are likely to outlast even Cassini. The trick is that precisely because Cassini is lingering in the neighborhood of potentially life-bearing orbs, they'll have to decomission her in a way so as not to contaminate anything with earth-borne bacteria, before her fuel runs out. Would that even be an issue around Uranian/Neptunian moons? We just don't know, do we? <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

3488 · Aug 14, 2007

Hi brellis, I think with a redundant Neptune orbiter, a potential impact with Triton might be considered an unacceptable risk. With a Uranus orbiter, it is less clear, but I have heard suggestions that Titania could be an issue as might Ariel, so I think with both Uranus & Neptune orbiters, when redundant, they both would have to be disposed off, probably being sent for atmospheric entry into the atmospheres of Uranus & Neptune respectively. I would suggest crashing them into Oberon (the Uranus one) & Proteus (the Neptune one) as approach images would reveal much. vogon13 suggests impacting Cassini into the Cassini Regio on Iapetus. I agree with him a full 100% on that proposal, as a future Saturn mission could look at the impact crater to check if the dark material is still accumulating & not only that, I realised that Cassini could send approach images in real time, great close ups too. Very true about the Voyagers. I am sure they will outlive Cassini as they have outlived Galileo too. Andrew Brown. <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

jaxtraw

Guest

mithridates

Guest

3488

Guest

jaxtraw

Guest

mithridates

Guest

3488

Guest

brellis

Guest

alokmohan

Guest

3488

Guest

h2ouniverse

Guest

3488

Guest

h2ouniverse

Guest

brellis

Guest

3488

Guest

alokmohan

Guest

3488

Guest

ihwip

Guest

3488

Guest

robnissen

Guest

3488

Guest

3488

Guest

jaxtraw

Guest

3488

Guest

brellis

Guest

3488

Guest

Similar threads

TRENDING THREADS

Latest posts

Share this page