Icy medium-sized planets

JonClarke · Dec 16, 2007

If a mars sized object were found in the Kuiper belt it would throw the whole dwarf planet idea into disarray. Which would be a good thing, since it is based on flawed assumptions, IMHO. 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>

MeteorWayne · Dec 16, 2007

I have to represent the other side of the argument, Jon <img src="/images/icons/smile.gif" /> If there were a Mars sized body out there, it would have most likely created a gap in the Kuiper belt, so would count as a full fledged planet by both definitions. The fact that there are no such gaps strongly suggests that such bodies don't exist, although the possibility exists that a plutino might not clear out the area. But then again, it would be a small mass (i.e. nowhere near Mars sized) plutino, and we have a few dozen of those. <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>

3488 · Dec 16, 2007

I suspect that there are several Pluto / Eris type objects awaiting discovery. Could you just imagine it if one was found & that New Horizons could encounter it, post Pluto??? 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>

MeteorWayne · Dec 16, 2007

Just pointing out that Pluto/Eris sized objects are rubble, something Mars massed would be expected to have a noticeable effect on the coorbital objects, whereas Pluto and Eris do not. <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>

h2ouniverse · Dec 16, 2007

MW, Actually there are gaps in KB. Several severe notches on density=fn(a). A big notch at a = 50 AU. (with a = semi-major axis). Some are due to resonances vs Neptune (that attract objects to some periods and deplete the neighbourhoods of the orbital energy diagram). And beyond 50 AU, there are for now too few objects reported (about 100) to draw reliable statistics. People who are currently hunting for Mars or Earth-sized objects do so beyond 100 AU. As a reminder the only object spotted beyond 70 AU is Eris... Too little for a statictic about depletion!!!!! Regards.

h2ouniverse · Dec 16, 2007

in reply to ------------ whereas Pluto and Eris do not. ------------- This is still to be demonstrated. FYI the ratio between total mass of plutinos and Neptune is of same order of magnitude than Mars versus Jupiter. And yet there are asteroids in the Asteroid Belt that have their orbit influenced by Jupiter AND Mars. The fact that the KBOs are not influencing each other is still an assumption in the models, not a demonstrated fact. (most models of KB represent KBOs as massless particles). Regards.

MeteorWayne · Dec 16, 2007

OK, what's your source on those gaps? My limited data all objects (greater than 200km diameter) does not show that. I don't count the Neptune resonant gaps as being related to objects in the KB, since by definition, they are related to Neptune, not KBs. I certainly agree that not a lot is known about the population greater than 50 AU to unequivocally judge. However, Eris' semimajor axis is only 68 AU. My database is over a year old, but shows 9 objects greater than 250 km diameter, including Sedna (a=492 AU). One of my first 2008 projects will be to update my solar system object database. Including Eris there were 7 objects with a=65 to 100 AU, and 3 /> 200 AU (with nothing in between.) I suspect that small number gap (between 100 AND 200 AU) is based on the difficulty of detecting such objects; with only 3 /> 100 AU, no statistics are meaningful. <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>

h2ouniverse · Dec 17, 2007

Hi MW, About population density : I will PM you. About detection of far objects, what is important is not a but r. Especially if you wan tot infer that "if something was there we would have detected it". Eris is the furthest object ever discovered in Solar System with r=96 AU. (currently close to its aphelion of 97 AU). Sedna's a is indeed larger but Sedna is currently at r=90 AU approaching perihelion. (so correction, mea culpa: two objects beyond 70 AU, not one) All other objects you quote are currently far closer to the Sun, close to their perihelia (most of them even lie in the classical belt at less than 50 AU btw). The pan-STARRS survey might bring more but the first run up to 2010 will be limited to plutos @ 250 AU, earths @ 640 AU, neptunes @ 980 AU and jupiters @ 1700 A. So you see there is still room for the discovery of "black sea" Pontian planets (my category "B"). Best regards.

h2ouniverse · Dec 19, 2007

Hi Andrew, Finally I found an element for your old question: "I wonder if such large planetary bodies, would have been found by now, by measuring the solar system's centre of gravity? " I've found on a site a quotation from Brian Marsden (in 2006): "The inner Oort cloud, which stretches from a few tens of billions of miles to a few hundreds of billions of miles from the sun, is much more stable than the edge of the region. If any objects orbit thereâ€”nobody knowsâ€”they would stay in place indefinitely. Brian Marsden of the Harvard-Smithsonian Center for Astrophysics speculates that there could be full-fledged Earth-size planets in this zone, circling unseen in the dark. "We would not have detected them observationally or dynamically," he says. " He also said "dynamically", which includes effect on CoG imho. Best regards.

3488 · Dec 19, 2007

Thanks Joel, Most interesting. At that distance, Earth sized ice worlds would have virtually no effect on the inner solar system, barely within the Sun's own Hill Sphere. I see your point. Even if very highly reflective like Enceladus, Triton, Eris, etc, they would be far too faint to be seen even with the HST & the largest ground based telescopes. Could you imagine if one was nudged sunward & became the mother of all comets??? <img src="/images/icons/laugh.gif" /> 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 · Dec 19, 2007

Yes. This being said you need something huge to deviate suddenly an Earth-massed "Pontus" planet from a tranquil orbit in IOC onto a very elliptical orbit.

h2ouniverse · Jan 22, 2008

On the Mercury thread we had as thought experiment the teleportation of Enceladus on Mercury's orbit. I was wondering how long it would take, if Earth was suddenly placed in the Kuiper Belt, for the oceans to completely freeze. Given the internal flux of 0.075W/m2, I am not sure that this could occur quickly. The atmosphere and the upper layers of the oceans should freeze quickly but the abyssal plains should take very long to freeze. Indeed Uranus has even less internal heat flux dissipated than Earth, and succeeds in keeping its interior very hot. However, it has a thick atmosphere that acts as an insulation. Does anyone have a clue?

h2ouniverse · Jun 2, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>We would then have IMHO as "Icy planetary object" an object that is differentiated between rock and ices and is: A) Ice dwarf planetary object = rocky core + layer of ices (with or without subsurface ocean) + no atmosphere (Ceres, Ganymede) or an atmosphere (thin: Triton, or thick: Titan) B) Icy medium planetary object = rocky core + a layer of warm ices + an open-air liquid ocean + a thick atmosphere (probably hydrogen-rich) C) Ice giant planetary object = rocky core + (potentially) a layer of warm ices + an open-air supercritical ocean + a very thick hydrogen-rich atmosphere (e.g; Uranus, Neptune) Posted by h2ouniverse</DIV> Hi all, Apparently the first of such medium-sized icy/watery planets that I hypothetized in this thread few months ago may have been dicovered at... 3000 light years away...http://www.space.com/scienceastronomy/080602-aas-tiny-planet.htmlExcerpt: "There's a new extrasolar planet on the block: a mini-orb likely covered with a deep ocean. And it takes the record for the lowest mass exoplanet to orbit a normal star, astrophysicists announced today. The li'l planet — weighing in at three times Earth's mass — grabs the lightweight title from a five Earth-mass planet just announced in April. The super-Earth is called MOA-2007-BLG-192Lb, after its host star MOA-2007-BLG-192L, which is located about 3,000 light-years from Earth. (A light-year is the distance light travels in one year, or about 5.88 trillion miles — 9.46 trillion kilometers.) ... The planet orbits its host star at about the same distance as Venus orbits the sun. But the new planet's host star is likely between 3,000 and 1 million times fainter than the sun, so the top of the planet's atmosphere is probably colder than Pluto. The astrophysicists suggest the tiny planet supports a thick atmosphere, which along with possible interior heating by radioactive decay, could make the surface as balmy as that of Earth. (And theory suggests the surface may be completely covered by a deep ocean). Most of the nearly 300 exoplanets identified to date have been discovered using the radial velocity method in which astronomers look for slight wobbles in a star's motion due to the gravitational tug of an orbiting planet. This stellar wobble technique has found mainly large, Jupiter-like planets or smaller planets that orbit too close to their host stars to harbor life."  Best regards

h2ouniverse · Jun 2, 2008

to Mithridates, btw, this is also relevant to our "Pontus" debate few days ago (http://www.space.com/common/community/forums/?plckForumPage=ForumDiscussion&plckDiscussionId=Cat%3ac7921f8b-94ec-454a-9715-3770aac6e2caForum%3ad148ee4c-9f4c-47f9-aa95-7a42941583c6Discussion%3a7de56fd9-6daf-43fa-a442-76fba58d3449&plckCategoryCurrentPage=0) Recall: "I do think such "pontic" planets exist (I would suggest that the first one discovered should be called "Pontus", for this is both the elemental (pre-olympian) god of water and a region bordering the Black Sea, suitable for an ever-in-the-dark oceanic planet).May be there is still one in the solar system, with one or three Earth masses, intermediate between Uranus/Neptune and Pluto/Eris, on an elliptical orbit, close today to its aphelion at say 200AU."  regards... <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/13/d6ca0692-c2a5-4e2f-9dd3-a8f925e2ca2a.Medium.jpg" alt="" />

h2ouniverse · Jun 18, 2008

New hints at a potential icy-medium-sized planet in Solar System:http://www.space.com/scienceastronomy/080618-planet-x.html#comments Lykawaka's model fits with a small "Pontus" in 100-200 AU range. I can't wait for PAN-STARRS to be operational.

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