Scattered Disk and Oort Cloud

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Anglocowboy

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<p>I was just reading something in Wikipedia that makes me ask the question:&nbsp; What is the difference between the Scattered Disk and the Oort Cloud?&nbsp; Are they the same thing?</p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> "Make like Siamese twins and split... and then one of you die." </div>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I was just reading something in Wikipedia that makes me ask the question:&nbsp; What is the difference between the Scattered Disk and the Oort Cloud?&nbsp; Are they the same thing?&nbsp;&nbsp; <br />Posted by Anglocowboy</DIV><br /><br />Not really. The scattered disk are asteroids generally still relatively close to the plane of the solar system ( and in prograde orbits, like 98% of the other material in the solar system), and much closer than the Oort Cloud, but further out than the Kuiper Belt.. The theoretical Oort cloud is a sperical shell around the solar system in all directions. I only use the term theoretical, because we have observed no objects in that location, but we have some proof that it exists as it is a source of comets in near parabolic orbits coming from all directions. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Anglocowboy

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Okay!&nbsp; So the Scattered Disk doesn't contain long period comets and is, as the name suggests, actually a disk.&nbsp; Is it a reasonable postulation (as I've heard from some) that&nbsp;our Oort Cloud could reach 3/4s the way to our&nbsp;nearest star?&nbsp; That doesn't seem correct because wouldn't the gravity of that star draw such objects into its own system?&nbsp; I don't know why I am so fascinated by the concept of the Oort Cloud.&nbsp; I guess it's just the idea of such&nbsp;lonely, cold places in the depths of space. <div class="Discussion_UserSignature"> "Make like Siamese twins and split... and then one of you die." </div>
 
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MeteorWayne

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Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Okay!&nbsp; So the Scattered Disk doesn't contain long period comets and is, as the name suggests, actually a disk.&nbsp; Is it a reasonable postulation (as I've heard from some) that&nbsp;our Oort Cloud could reach 3/4s the way to our&nbsp;nearest star?&nbsp; That doesn't seem correct because wouldn't the gravity of that star draw such objects into its own system?&nbsp; I don't know why I am so fascinated by the concept of the Oort Cloud.&nbsp; I guess it's just the idea of such&nbsp;lonely, cold places in the depths of space. <br />Posted by Anglocowboy</DIV><br /><br />Well, it depend of the mass of which star you are considering in each direction. The nearest star system (3 stars) is alpha Centauri; the total mass of this syetm is about 2 times that of the sun, so to me it makes sense that in that direction, the Oort cloud could not go much further than 1/3 of the distance, or about 1.4 light years. However, I haven't investigated that, just doing rough calculations off the top of my head, and haven't included any complicating factors. Should be in the ballpark, though. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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Anglocowboy

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Okay here's a nifty one then.&nbsp; Would it be theoretically possible for the Oort clouds of neighboring stars to exchange objects with one another?<br /> <div class="Discussion_UserSignature"> "Make like Siamese twins and split... and then one of you die." </div>
 
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3488

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'><font color="#ff0000">Okay here's a nifty one then.&nbsp; Would it be theoretically possible for the Oort clouds of neighboring stars to exchange objects with one another? <br /> Posted by Anglocowboy</font></DIV></p><p><font size="2"><strong>Indeed it is possible but would be very difficult as the gravitaional bond to the star is very tenuous, more likely Oort Cloud comets would more likely become Intersteller Rogues, taking up their own orbits around the galactic centre, no longer gravitationally bound. There could be billions of these things in intersteller space.&nbsp;</strong></font></p><p><font size="2"><strong><font color="#000000">It has been suggested quite seriously that <font size="2" color="#000080">90377 Sedna</font>, could be a captured intersteller object, though proof is lacking in that department. Further observations will help.</font></strong></font></p><p><font size="2"><strong><font color="#000000">It is not 100% certain that the Oort Cloud physically exists, but observations of the aphelia of very long period comets suggests that it does. Individual cometary nuclei this far out will be faint to say the least, approaching 60th Magnitude. The faintest IIRC observed by the HST, Keck etc is 34th magnitude, so we are talking 26 magnitudes or approx 25,148,408,816 (back of an Excel Spreadsheet calculation, 2.512 x 2.512 26 times) fainter than the faintest object yet seen (a pretty bloody tall order). &nbsp;</font></strong></font></p><p><font size="2"><strong><font color="#000000">To further MeteorWayne's post, the Sun's Hill Sphere (the sphere of gravitational dominance) will vary in size, due to varying distances to the nearest stars & also the varying mass of passing stars. Currently as Wayne says, the Alpha Centuri trinary system is the closest known steller system to the Solar System, but that has not & will not always be so.</font></strong></font></p><p><font size="3" color="#000080"><strong>Check out Gliese 710.&nbsp;</strong></font></p><p><strong><font size="2">Andrew Brown.&nbsp;</font></strong></p> <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>
 
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Anglocowboy

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I'd say the Oort Cloud definately exists, although the term cloud may not be the best term.&nbsp; It&nbsp;is certainly not&nbsp;directly observable due to the dreadfully large distance between objects therein. But there must be many long period comets out there if several have been observed so far. Isn't Comet Halley supposedly an Oort Cloud object (albeit a rather frequent visitor to the inner reaches of our solar system)?<br /> <div class="Discussion_UserSignature"> "Make like Siamese twins and split... and then one of you die." </div>
 
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BrianSlee

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I was going to ask this in the Tunguska thread but never got a chance.&nbsp; I believe we have evidence that mass extinction events are periodic in nature.&nbsp; If this is true how long is the period (I recall a figure of 650 million years).&nbsp; Then how long since the last one.&nbsp; And finally given the period, is it possible that a large swarm of objects from the Kuiper belt or the Oort cloud is responsible for the events and given the&nbsp;period, which of the two would be the likely culprit. <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>
 
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MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I'd say the Oort Cloud definately exists, although the term cloud may not be the best term.&nbsp; It&nbsp;is certainly not&nbsp;directly observable due to the dreadfully large distance between objects therein. But there must be many long period comets out there if several have been observed so far. Isn't Comet Halley supposedly an Oort Cloud object (albeit a rather frequent visitor to the inner reaches of our solar system)? <br />Posted by Anglocowboy</DIV><br /><br />Well, sort of. It used to be an Oort cloud comet, but has been trapped in the inner solar system.&nbsp;Halley's Comet (1P/Halley) is the reference for a class called "Halley type comets". Over time about 1% of the Oort cloud comets evolve into shorter orbits called Halley class, the remainder being ejected from the solar system.</p><p>They are defined as comets with periods < 250 years and encounter velocities with Jupiter larger than Jupitr's obital velocity. This amounts to about one new Halley class comet every 4 years resulting in a steady state of about 300 such comets at any given time.</p><p>The Oort cloud origin is still evident in the proportion of retrograde orbits, i.e. those orbiting the sun in the opposite direction from 98% of the rest of the Solar System.</p><p>The above condensed from Peter Jennisken's "Meteor Showers and their Parent Comets", derived from the work of many others.</p><p>MW</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
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