Comet Holmes

[3488]

Hi cnick,<br /><br />To reinforce what MeteorWayne has said, I have supplied some image links below.<br /><br />Comet Wild 2 Nucleus.<br /><br />Twelve views of Comet Wild 2.<br /><br />Comet Wild 2 'Spires', as MeteorWayne explained.<br /><br />Comet Wild 2 surface features.<br /><br />Comet Wild 2 white spots, exposed ice.<br /><br />A whole lot of Comet Tempel 1 stuff from Deep Impact.<br /><br />How Comet Holmes compare to these, I dunno, but I suspect more like Tempel 1.<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>

 

[MeteorWayne]

As MichaelMozina pointed out there's a Kreutz sungrazing comet heading toward the sun on the SOHO LASCO/C3 image here; it's easiest to see if you look at the GIF (36 MB) or MPEG (5MB) movie.<br /><br />It's moving up from below the sun<br /><br />Also visible are Mercury (moving from right to left below the sun) and Jupiter (Just entering the frame on the left.<br /><br /> SOHO <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>

 

[3488]

Thanks MeteorWayne,<br /><br />That's pretty cool, Antares drifing off, Jupiter coming in, Mercury closing in & the tiny<br />Kreutz.<br /><br />Great 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>

 

[MeteorWayne]

Both the comet and Mercury are now close enough to the sun to show on the LASCO/C2 animation, right at the end.<br /><br />Looks to me like the comet evaporated before it made it to perihelion.<br /><br />MW <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>

 

[3488]

That was what happened in my opinion.<br /><br />I must check the SOHO site more often, I just forget it's there. <img src="/images/icons/crazy.gif" />.<br /><br />You have found some real nice things lately. <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>

 

[MeteorWayne]

Like I said, it's the benefit of many eyes and minds. No one person can keep up with what we all do as a community, my friend. <img src="/images/icons/smile.gif" /><br /><br />Wayne <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>

 

[cnick]

MeteorWayne and SolarSystem:<br />Thanks for all the links and explanations concerning Comet Holmes in particular and comets in general. I have been studying them and others too, and have turned up some interesting stuff. I might as well read, since we have had some pretty bad weather here... when it hasn't been snowing or sleeting it has been cloudy. My telescope has cobwebs.<br />MeteorWayne has indicated that space probe discoverys are consistent with the "Dirty Snowball" Theory of comets. Nevertheless, that theory has failed to predict, prompting Nasa scientists to often use such expressions as "surprising" and "totally unexpected" with their discoveries. <br />A few points (and questions):<br /><br />1) the discovery by Stardust that formation occurred under hot conditions was surprising because the theory predicted formation in the cold nether regions of the outer solar system<br /><br />2) the comet shines by reflected light but also by it's own light: "the dust reflecting sunlight directly and the gases glowing from ionisation." Wikpedia "Comet"<br /><br />3) comets can "explode," although this may or may not apply to Holmes, it seems to provide a similar case in that comet Linear was observed brightening up unexpectedly:<br />http://hubblesite.org/newscenter/archive/releases/2000/26/text/ <br /><br />4) even more interesting, the same site expresses puzzlement over the low temperatures:<br />"The eruption, the comet's equivalent of a volcanic explosion (though temperatures are far below freezing, at about minus 100 degrees Fahrenheit in the icy regions of the nucleus or core), spewed a great deal of dust into space."<br />I believe Comet Linear was slightly closer (less than 2 au) than Holmes when this explosion occured.<br /><br />5) consistent with my statement that comet photos looked like rocky asteroids (perhaps the main difference between a comet and asteroid is the shap

 

[MeteorWayne]

1. Stardust did not discover that the comet formed in hot conditions. Rather it discovered that some of the small particles included in the comet were formed at the warm temperatures, implying far more mixing of the solar dust disk. That was the surprising part.<br /><br />2. Yes, comet gas ions do glow, but the source of the energy is the suns UV radiation. So they do not technically glow "by their own light" rather thay are reradiating the energy absorbed from the sun.<br /><br />3. Comet Linear did not "explode". It survived the event.<br />"When the Hubble telescope first spied the comet 74 million miles (120 million km) from Earth, it watched the icy object's brightness rise by about 50 percent in less than four hours. By the next day, the comet was a third less luminous than it had been the previous day. On the final day, the comet was back to normal — one-seventh less bright than at peak level. <br /><br />During the outburst's peak, the astronomers believe that the comet jettisoned the piece of its crust seen days later in the tail. The renegade <font color="yellow">fragment </font>oved away from the core's weak gravitational grasp at an average speed of about six miles per hour, which is a little more than a brisk walking pace. "<br /><br />So it ejected a piece of crust, probably very similar to what comet Holmes did.<br /><br />4. You: "even more interesting, the same site expresses puzzlement over the low temperatures" <br /><br />That is not what they said. No surprise was expressed regarding the temperatures; rather the surprise was in the luck in capturing the outburst.<br /><br />5 How can a rock ice mixture that is at less than -100 F be described as slushy.<br />First of all the ice would be hard as a rock.<br />Second, slush requires liquid water, which cannot exist at that pressure and temperature.<br /><br />There's Ice, then gas. That's what sublimate means.<br /><br />6. If it's a comet it's got ices, otherwise it would not create a tail. Once again <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>

 

[3488]

MeteorWayne has explained it extremely well (I've been out all day, otherwise <br />I would have answered sooner).<br /><br />As MeteorWayne has said & I myself have tried to explain, the minor bodies of our<br />Solar System, do not conveniently fall into two distinct camps as was thought, so 20 - 30<br />years ago when comets were ice balls & asteroids were rock.<br /><br />Now we know that there is a broad spectrum of said objects, from metal rich<br />asteroids like 16 Psyche (virtually pure iron), silicate rock asteroids like 951 Gaspra, 243 Ida<br />basalt rock 4 Vesta, carbon rich, 1 Ceres, 253 Mathilde, rock / ice composite 107P/Wilson-Harrington<br />AKA 4015 Wilson-Harrington<br />& comets various from carbon rich to nearly pure ice.<br /><br />The source body of the Annual Geminids, Asteroid 3200 Phathon was most<br />definately a comet in the past, but the volatiles have boiled off leaving a small cinder like<br />asteroid, the core of the original comet.<br /><br />Comet Wild 2, contains materials & crytals that formed in extremely hot conditions, but<br />this does not mean that Wild 2 formed close to the embryonic Sun. It means therefore that<br />Wils 2 was contaminated later on, by these materials, being ejected from the inner <br />solar system, to intersteller space, which Wild 2 captured some on the outbound journey<br />long ago. <br /><br />I do not see any conflict at all.<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>

 

[heyscottie]

I took another look at Holmes last night for the first time in a long time, and was surprised at how bright it still remained. It's definitely still naked-eye, and much larger than before. I'd looked for it several weeks ago, in the wrong area, thinking it was moving in the opposite direction than it actually was, and couldn't find it then. But once I recalibrated myself, it was certainly easy enough to find. It continues to amaze me!

 

[cnick]

Wayne:<br />Thanks for your response, I would like to answer a few of your points. Some points of contention are the result of my failure to choose the best word or wording for the situation. For this I apologize.<br /><br /><br />"1. Stardust did not discover that the comet formed in hot conditions. Rather it discovered that some of the small particles included in the comet were formed at the warm temperatures, implying far more mixing of the solar dust disk. That was the surprising part. "<br /><br /><br /><br />You miss my point. The "Dirty Snowball" theory has to be modified once again (in that it postulates comet formation in the cold outer regions of the solar system) to account for the presence of particles that were formed under hot conditions. I do not know where or when comets were formed, different comets may have been formed under varying conditions at different times. If a theory proposes that comets were formed under hot conditions, the fact that Stardust found particles that were formed under hot conditions would be consistent with such a theory without having to add the ad hoc supposition that the material migrated to the outer reaches of the solar system. I have proposed no such theory, nor do I feel qualified to do so. I am an amateur astronomer just trying to educate myself about these mysterious objects called comets.<br /><br /><br />"2. Yes, comet gas ions do glow, but the source of the energy is the suns UV radiation. So they do not technically glow "by their own light" rather thay are reradiating the energy absorbed from the sun." <br /><br /><br /><br />A comet's coma and tail(s) are composed of dust particles and ionized gases. The dust particles reflect sunlight. The ionized gases glow from interaction with the charged particles which make up the solar wind, not from UV radiation. This is analogous to a neon light, or the Aurora. I use the term "ionized gases" because that seems to be the practice in astronomy articles, but the more correct t

 

[MeteorWayne]

Thanx for the clarifications.<br /><br />OK, here's my thoughts.<br /><br /><font color="yellow">"You miss my point. The "Dirty Snowball" theory has to be modified once again (in that it postulates comet formation in the cold outer regions of the solar system) to account for the presence of particles that were formed under hot conditions. I do not know where or when comets were formed, different comets may have been formed under varying conditions at different times. If a theory proposes that comets were formed under hot conditions, the fact that Stardust found particles that were formed under hot conditions would be consistent with such a theory without having to add the ad hoc supposition that the material migrated to the outer reaches of the solar system. I have proposed no such theory, nor do I feel qualified to do so. I am an amateur astronomer just trying to educate myself about these mysterious objects called comets. "[</font><br /><br />Certainly many comets formed under varying conditions at different times.<br /> One thing to realize is the source regions of the comets samples so far.<br /><br />The 4 nuclei we visited come from 2 very different sources, the Oort cloud and the asteroid or Kuiper belt. {Oort- Halley, AB/KB-Wild2, Borelly, Tempel/9}<br /><br />Only one has had a physical sample that allowed us to determine that the materials were formed at higher temperatures than the expected source regions, and even that was for some particles, not the formation region of the comet. The fact that stardust saw previously heated particles <i> as a small percentage of the mixture </i> suggests that the early solar sytem was more mixed than we thought. This is not a modification to the dirty snowball/icy dirtball model, but rather a modification to the early history of the solar system.<br /><br />In other words, the comet formed under cold conditions, but some of the dust that was incorporated into it must have come from closer in the solar system, since they <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>

 

[3488]

APOD. Monday 31st December 2007.<br /><br /><img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> Happy New Year 2008. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <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>

 

[adrenalynn]

Nice focal reduction - but that's a composite for sure... Still awesome!<br /><br />Holmes has several more good conjunctions coming up, including one over the next few nights, I believe. He's at about a magnitude 5 now.<br /><br />If the skies are clear, Tuttle has a run in with one of the M-objects tonight, I believe. I'd have to check and I'm not feeling all that hot at the moment. Tuttle is between Mag 6 and 7 right now. <div class="Discussion_UserSignature"> <p>.</p><p><font size="3">bipartisan</font>  (<span style="color:blue" class="pointer"><span class="pron"><font face="Lucida Sans Unicode" size="2">bī-pär'tĭ-zən, -sən</font></span></span>) [Adj.]  Maintaining the ability to blame republications when your stimulus plan proves to be a devastating failure.</p><p><strong><font color="#ff0000"><font color="#ff0000">IMPE</font><font color="#c0c0c0">ACH</font> <font color="#0000ff"><font color="#c0c0c0">O</font>BAMA</font>!</font></strong></p> </div>

 

[MeteorWayne]

I know this thread's been sleeping for a while, but a possible relavant point to the reactivation of this comet after more than a century has come up.<br />It was included in a note in S&T, so I followed up.<br /><br />The below data is from Gary Kronk's Cometography website. link <br /><br /><font color="yellow"><br /><br />Close approaches to planets: During the 20th century, this comet made two close approaches to Jupiter. There are also two close approaches to Jupiter during the 21st century. (From the orbital work of Kazuo Kino&%$#@!a and G. W. Kronk)<br /><br />0.54 AU from Jupiter on 1908 December 9 <br />...increased perihelion distance from 2.12 AU to 2.34 AU <br />...increased orbital period from 6.86 to 7.33 years <br /><br />1.03 AU from Jupiter during 1968 April <br />...decreased perihelion distance from 2.35 AU to 2.16 AU <br />...decreased orbital period from 7.35 to 7.05 years <br /><br />1.50 AU from Jupiter during 2004 January <br />...decreased perihelion distance from 2.17 AU to 2.05 AU <br />...decreased orbital period from 7.07 to 6.88 years <br /><br />0.85 AU from Jupiter on 2051 April 8 <br />...increased perihelion distance from 2.06 AU to 2.21 AU <br />...increased orbital period from 6.89 to 7.21 years </font><br /><br />At the time of the discovery outburst in 1892, it had passed perihelion of 2.12 AU 5 months earlier.<br /><br />The comet was lost from 1906 to 1964. It appears that the orbit change in 1908 put it in the deep freeze, never getting close enough to become more than minimally active.<br />In 1964, it reached a magnitude of ~ 18.7, and has been observed every return since.<br />Why was it sen in 1964? Perhaps due to the more accurate orbit predictions (as computers improved the calculations) and increased sensitivity of photographic methods?<br /><br />The 1968 close approach to Jupiter decreased the perihelion from 2.35 to 2.17 AU, moving it from the freezer to the <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>