Pluto

3488 · Aug 10, 2006

Thats fine. You are welcome MeteorWayne. Planetary science is my sort of thing & I know the list above is correct. I will re-post it with diameters of the objects when I have time. <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>

MeteorWayne · Aug 10, 2006

3488, As you might be able to tell, meteors are my sort of thing <img src="/images/icons/smile.gif" />. I always begin my meteor lectures with an overview of the solar system, and this gives me some ideas on how to present some of the data. The list will also add an entertaining spin to our next debate on Pluto's planetary status. I got a chuckle out of list 2, the "small" bodies of the solar system, led by our own terra firma. Most people are amazed to find that the earth is only a bit more than 0.2% of the non solar mass of the solar system. Thanx again <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

alokmohan · Aug 10, 2006

IAU meeting is scheduled to be held in september.Percival Lowell was looking fo a big planet beyond neptune.Lowell kept on waking night after night to see planet more massive than jupiter.This contiued till death.Ater Lowell his student ,Clyde Tombough took on the task.By that time astronomers had found the blink comparator method,some thing not available during Lowells time.He kept on photographing sky night after night to see the position of stars.AND HE SAW SOMETHING MOVING RELATIVE TO FIXED STARS.He thought is to be planet big size ,as LOWELL CONCEIVED.That time there was no way to measure mass of planet .Tombough naturally made mistake it to be Lowells planet.It was not before 40s that scientists knew about mass of pluto.When it was learnt that it was too small.they had already named it planet .Dicovery by mistake ab initio.

bdewoody · Aug 10, 2006

Of course I'm not a professional in this field but going by a statement Carl Sagan made during one of the Cosmos episodes. An object large enough to have enough mass to make the object spherical and the object does not orbit one of the planets should qualify the object as a planet. All of the asteroids I've seen pictures of are very irregularly shaped either like a potato or a peanut. We won't know for sure I guess until the probe gets there what Pluto looks like but I'd guess it's a sphere. Even if one of the moons of Jupiter or Saturn were bigger than earth it would still be a moon and of course earth is a planet. <div class="Discussion_UserSignature"> Bob DeWoody </div>

3488 · Aug 10, 2006

Hi MeteorWayne. I gathered that you were interested in Meteors. Yes I know, the Earth only contributes a tiny amount of planetary mass. Hi Alokmohan. Yes Percival Lowell was looking for another Gas Giant beyond Neptune. Pluto being discovered like that was luck. Clyde Tombaugh was a genius at observation. Apparently has also spotted 2003 UB313 (Xena) & Quaoar as well, but failed to identify them (much like Galileo in 1612 with Neptune). Tombaugh did make the mistake of beleiving the object he found to be the Gas Giant expected by Lowell. Soon afterwards, it became apparent, Pluto was not a gas giant & was maybe Earth sized at best. Later, the size estimates shrank to between that of Mars & Mercury for some years. More recently we now know Pluto is barely 60% of the diameter of our moon. It was because that Pluto was thought to be dark (due to distance from the sun & having a dark surface) meant Pluto had to be fairly large. The first fact of weak sunlight is still true, but Pluto is highly reflective with a surface of Methane & Nitrogen ice, hence smaller & somewhat colder than was first thought. The objects Enceladus, Triton, Pluto, 2003 UB313 (Xena), Quaoar & 2004 DW (Orcus), all have ice rich surfaces that make them so bright & cold. <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 · Aug 10, 2006

Hi, Andrew (3488); Is this mass bias or diameter bias <img src="/images/icons/wink.gif" /> ? I have a minor edit here, you forgot 2005 FY9. When I looked this up to get a link for the lurkers to read, I got a pleasant surprise. It says what I was going to say: "Size The albedo of 2005 FY9 remains unknown leading to a significant uncertainty in the object’s size. The detection in infrared by the Spitzer space telescope, combined with the similarities of spectrum with Pluto yield a conservative estimate of 1660 km. This is similar to the size of 2003 EL61 making 2005 FY9 the largest known Kuiper belt object after 2003 UB313 and Pluto. However, should the albedo prove to be closer to that of Quaoar for example, the size of the object diameter could reach 3000 km. 2005 FY9 is currently visually the second brightest Kuiper belt object after Pluto having the apparent magnitude of nearly 17". Now, personally I think, based on it's perihelion and spectrum, that the object is permanently covered with brright nitrogen ice, which is extremely transparent with no spectral signature and I think is quite thick, covering methane ice and protecting it from ultraviolet light, based on the spectrum of the object. The methane is seen as though through frosted glass. However, I must say that my idea is pretty tentative, since it's so far away and it's so hard to measure these things. My guess is that the albedo is very high, thus I would place the "size" (diameter) estimate as below the lower end of what the article says. I have a doctor's appointment this afternoon, toodle-ooh. Couldn't find Mike Brown's article, now time's up.

vandivx · Aug 10, 2006

untill we can make routine travels around solar system in general, we have no business changing Pluto's designation as a planet for we know we are still ignorants currently and as such we should cease and desist with such ridiculous attempts at definitive clasification and simply call anything we find out there at the limits of solar system a planet automatically if all that time and thinking efforts spent on this debate were to be channeled to new discoveries, we would now be much further ahead than we are, perhaps capable of traveling out there on manned mission to decide the issue vanDivX <div class="Discussion_UserSignature"> </div>

robnissen · Aug 10, 2006

According to your definition both the asteroids Ceres and Vesta should be planets. Ceres is definitely spherical, and Vesta is mostly spherical (it appears that it suffered a major impact that made it slightly less spherical. BTW, a cool fact I just found out while looking this up -- a piece of Vesta was found in Austrailia, making it, Mars and the Moon the only bodies that have had pieces land on earth, at least AFIK.

3488 · Aug 11, 2006

Hi mikeemmert: I did overlook 2005 FY9. Whilst I had heard of the object, its size range was an unknown. Your article seems to show that it is indeed larger than 2004 DW (Orcus), assuming its albedo is low (dark). If so 2005 FY9 is indeed the largest KBO, knocking 2003 UB313 (Xena) into second place & Pluto third. Also 2005 FY9 is a long way north of the ecliptic, currently in front of the constellation of Coma Berenices. Has there been any more about Sedna? Peculiar object. Wonder if it was snagged by the sun from a passing star? RobNissen: Interesting. I had heard of Vesta meteorites before. I did hear a while back, that a suspected Mercury meteorite had been found in the Sahara Desert in Egypt. I have found nothing else on this, so I assume that theory has gone out of the window. Asteroid 4 Vesta has a giant south polar crater with a 13 kilometre / 8 mile high central mountain (according to Hubble data). <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>

JonClarke · Aug 11, 2006

I would be quite happy to have any body in a heliocentric orbit with enough mass to form a sphere called a planet. So Ceres, Vesta etc. are definitely planets. I basis this on process, the graviational collpase and differentiation of a body results in profound changes to its structure and composition that links it much more closely to much larger rocky planets than to smaller, undifferentiated bodies. IMHO! The HED family of meteorites are all believed to come from Vesta. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

alokmohan · Aug 11, 2006

Pluto is lucky guy.It became planet by mistake.Now it is difficult to demote it.

bdewoody · Aug 11, 2006

I think when originally discovered four of the "asteroids" including Vesta and Ceres were called planets and then minor planets. It was only after the asteroid belt was discovered that they were demoted. <div class="Discussion_UserSignature"> Bob DeWoody </div>

alokmohan · Aug 11, 2006

They were named asteroids,means star like.Piazzi,discoverer named them so.They were never called planet.

mikeemmert · Aug 11, 2006

There's been a history of assuming low albedos for KBO's. Early in the history of the discoveries of these objects, they were uniformly assumed to have an albedo of .04. This started with Pluto. It's mass was thought to be known, however this was in error, it's not big enough to pull Neptune and Uranus around (I heard the error was thought to be that the center of light of an object is not necessarily the center of mass). As the years went by and telescopes improved, Pluto shrank, with some comedians suggesting that the planet would disappear by early this century. If the IAU demotes Pluto, the comedians will have been right, the planet disappeared <img src="/images/icons/laugh.gif" /> ! Thermal infrared measurements have almost uniformly reduced the size estimates of the larger KBO's. However, these measurements are difficult to do. Essentially, the telescope measures the temperature and humidity of the Earth's atmosphere rather than the temperature of the object. Space-based infrared measurements would help. Unfortunately presently available equipment is inadequate. The Challenger disaster caused a redesign of the Spitzer space telescope. Cheapskates in Congress couldn't be persuaded to part with a Titan missile, going instead with a Delta II bottlerocket. We have a nomenclature problem with infrared radiation, IMHO, as well as solar system bodies. Most people think of "heat" radiation. The wavelengths available from the ground are fine for hot objects, like stars. Thinking of short wavelenth infrared as temperature measurements is a bias introduced during the cold war, when there was a huge market for detecting the tailpipes of jet aircraft, which are hot but not as hot as the flares pilots dropped to confuse the nonintelligent brains of antiaircraft missiles. At the temperatures of KBO's, those wavelengths are not thermal radiation at all, but rather reflected sunlight. The instruments, techiques, and van

harmonicaman · Aug 11, 2006

Alokmohan - Well; in 1801 Guiseppe Piazzi at the Palermo Observatory discovered Ceres Ferdinandea (name later shortened). It was found to be located at exactly the distance predicted by Titus-Bode's Law (which is now considered a mere coincidence). The very next year, in 1802, Heinrich Olbers discovered a second small body named Pallas. These two new additions to the solar system were listed along with the rest of the planets in order of increasing distance from the Sun. They were also given symbols(1.) by their discoverers to be used when recording observations. Many astronomers disagreed that these objects were large enough to be considered as planets; especially John Hershel, who called them "Asteroids". The acceptance of the newly discovered asteroids was so matter-of-fact that introductory texts (such as the First Steps to Astronomy and Geography [1828]) listed the planets as "Eleven": Mercury, Venus, Earth, Mars, Vesta, Juno, Ceres, Pallas, Jupiter, Saturn, and Herschel. (Herschel was an alternate name for Uranus, after its discoverer). Only after 1851, when more than 15 asteroids had been discovered and things started getting complicated, did asteroids start becoming known as minor planets and asteroids in scientific journals. It wasn't until around the turn of the century that the term "Asteroid" was universally accepted. 1. Old asteroid symbols. (Gleaned from the web and an old text book...)

3488 · Aug 11, 2006

Yes why not, mikeemmert. I reckon the albedo is low, due to radiation darkening of Methane Ice, making 2005 FY9 dark red. I see your point as well. With larger KBOs being found now, I think New Horizons 2 should be restarted. I wonder, what do you think of Sedna? Do you think that the Sun grabbed it from a passing star in the remote past?? Would be interesting to think that we may have an object orbiting our Sun that was originally part of another Solar System. If Sedna is indeed proven to be an exo solar body, I think that New Horizons 2 should be sent to Sedna, possibly an orbital mission. Such an object would tell us much, perhaps clues as to the nature of its original parent star (sunlike, red dwarf, brown dwarf, etc). OK if you are right, I'll post an image of a crow. harmonicman: I like your link to the old Asteroid symbols. I see 433 Eros is included. Perhaps they should add all of the other ones visited by spacecraft too: 951 Gaspra (Galileo). 243 Ida (Galileo). 253 Mathilde (NEAR Shoemaker). 5535 Annefrank (Stardust). <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>

bdewoody · Aug 11, 2006

Thank you for verifying my post harmonicaman <div class="Discussion_UserSignature"> Bob DeWoody </div>

ittiz · Aug 11, 2006

From what I read here Pluto will probably be designated as a dwarf planet. The guy who made the post seems to think this means it won't be a planet anymore but I think he misinterpreted. I think all small round bodies will be put in this new category. So Pluto won't be demoted necessarily it will just be re-categorized just like all the other planets will be. Where they draw the line between the Terrestrial and Dwarf planets will be hard to say. I personally think it should be drawn at differentiated interiors. Although I guess this would lead to some ambiguity with Pluto because it's almost heavy enough to have one, something that probably wouldn't be resolved until the flyby. This new definition will probably also move things like "Xena" and Ceres and several other bodies into the Dwarf Planet category.

harmonicaman · Aug 11, 2006

(Repost) This argument is really all about semantics, nomenclature and taxonomy! It has little at all to do with theories of how the Solar System developed or the how's and why's concerning the origins of these new-found celestial masses orbiting our Sun -- although, as we learn more, this may change! Obviously, more KBOs and Oort Cloud objects will be discovered in the future, and in Science all things must be systematically classified with similar units in a process called disambiguation. The International Astronomical Union (IAU), which is a member of the International Council of Science (ICSU), is responsible for maintaining a unified system of astronomical classification. Within the IAU is the Working Group for Planetary System Nomenclature (WGPSN) which maintains the astronomical naming conventions and planetary nomenclature for orbiting bodies. This is the seminal authority which will decide on a plan to disambiguate the Solar System. Just like Ceres has been reclassified as a mere asteroid, rather than a major planet; it is my opinion that Pluto will also have to be redesignated to fit the new realities caused by recent discoveries! This isn't a bad thing. In the end it will help us get a clearer picture of the structure of the Solar System and in the future there may have to be several sub-classifications as new objects are discovered. The Kuiper Belt and Oort Cloud may someday have to be separated into several sub-sets such as inner and outer belts and/or areas far removed from the plane of the elliptic; to suggest a few examples. The same thing was done for the rings of Saturn as we discovered many new ring divisions! It's just too cumbersome to call everything under the Sun a "Planet". I think new names such as dwarf planet mesoplanet, planetesimal, microplanet, planetoid and the like, will have to become a part of the Solar Systems' lexicon, and i

ittiz · Aug 11, 2006

Is this supposed to be a reply to my comment? I doesn't seem to apply.

harmonicaman · Aug 11, 2006

Ittiz - No, it isn't a specific reply to your post. This exact same topic has come up maybe 25 times in the past couple of years, so I just cut-and-pasted an old general response instead of taking the time to create an entirely new thought -- it saves time and seemed to be generally applicable to the thread...<img src="/images/icons/rolleyes.gif" />

mikeemmert · Aug 11, 2006

<blockquote>In reply to:<hr />I wonder, what do you think of Sedna? Do you think that the Sun grabbed it from a passing star in the remote past??<hr /></blockquote>OK, I'll speculate a little (what the heck, I have no reputation to ruin). As a matter of fact, I do think that. When I got GravitySimulator, it came with a sample simulation that showed exactly such a scenario. Here's the thread that shows why I developed that particular simulation.<blockquote>In reply to:<hr />Would be interesting to think that we may have an object orbiting our Sun that was originally part of another Solar System. If Sedna is indeed proven to be an exo solar body, I think that New Horizons 2 should be sent to Sedna, possibly an orbital mission. Such an object would tell us much, perhaps clues as to the nature of its original parent star (sunlike, red dwarf, brown dwarf, etc).<hr /></blockquote>That thread's real long but a very interesting read, if only for the thinking process revealed. Essentially, I had modeled flybys of a binary composed of Triton and Xena as a result of my very first post on Uplink as a "quark", 2003 UB313 is the lost moon of Triton. Tony Dunn turned me on to GravitySimulator, and I started simulating flybys. But there was something wrong with the results. Dr. Edward Belbruno sent me a short pointed e-mail asking how I could explain Xena's inclination (44 degrees, very steep). The best I could get was about 30 degrees. Then came the discovery of 2004 XR 190, Buffy. It also has a steep inclination, I think 46 degrees (?), but it has a circular orbit - at 47 AU, right at the Kuiper Belt cutoff!!

yevaud · Aug 11, 2006

We have a nomenclature problem with infrared radiation, IMHO, as well as solar system bodies. Most people think of "heat" radiation. The wavelengths available from the ground are fine for hot objects, like stars. Laypeople, perhaps. Not professionals in the field of Remote Sensing. They look at discreet bands such as Near IR, Far IR, and Thermal. And the bands used are flexible, not fixed as you might think. Also, I doubt anyone is really attempting to obtain thermal imagery or solid measurements of KBO's from the surface. They know it's virtually impossible. Just FYI. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

mikeemmert · Aug 11, 2006

<blockquote>In reply to:<hr />Also, I doubt anyone is really attempting to obtain thermal imagery or solid measurements of KBO's from the surface.<hr /></blockquote>Well - there have been some attempts. Notably, the diameter of Xena was announced with great fanfare as being over 2800 km. I do note, however, that they have stopped calling submillimeter wavelengths "infrared" and this is an advance. However, in the popular lexicon IR is still painted with a wide brush. This makes a good analogy, BTW, to the thread topic. Lumping all radiation from 0.7 to 100 microns as "infrared" is limiting and in some cases misleading. It's the same calling all round objects "planets". This measurement messed up my project, since I used the mass of Triton to model the Xena/Triton flyby of Neptune.<blockquote>In reply to:<hr />They know it's virtually impossible.<hr /></blockquote>They got a fairly good (they think) measurement of the diameter of Xena from HST, and it turned out to be considerably smaller. It was a very-near identical twin to Pluto. I have shifted my hypothesis somewhat (after squaking a little) and now hold that the Neptune Lagrange binaries were Pluto sized. The submillimeter measurements were announced with some qualifiers, however. It was stated that, if Xena had a very slow axial spin, or if it's pole happened to be pointed directly at the sun, then the estimate published would be an overestimate. These factors would cause the surface to be warmer. Nobody has detected any spin for Xena. This could be because of a pole-on orientation. It could also be because the surface of the object is uniform in coloring and brightness. Pluto has a non-uniform surface brightness; it's albedo measures between 0.49 and 0.66. I think we need more and better space-based observatories which can detect and measure wavelengths between 5 and 100 micro

alokmohan · Aug 13, 2006

I never knew Herschel was a planet in the past.Your post is enlightening.There was 15 planets once on a time!!!CONGRATS

Pluto

3488

Guest

MeteorWayne

Guest

alokmohan

Guest

bdewoody

Guest

3488

Guest

mikeemmert

Guest

vandivx

Guest

robnissen

Guest

3488

Guest

JonClarke

Guest

alokmohan

Guest

bdewoody

Guest

alokmohan

Guest

mikeemmert

Guest

harmonicaman

Guest

3488

Guest

bdewoody

Guest

ittiz

Guest

harmonicaman

Guest

ittiz

Guest

harmonicaman

Guest

mikeemmert

Guest

yevaud

Guest

mikeemmert

Guest

alokmohan

Guest

Similar threads

TRENDING THREADS

Latest posts

Moderators online

Share this page