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Planet X Larger Than Pluto? 561

nova_planitia writes "The Minor Planet mailing list is buzzing with the discovery by an amateur astronomer of a 17th magnitude object 51 astronomical units from the Sun, tentatively designated 2003 EL61. For those not versed in astronomical lingo, this is an object several times brighter than Pluto even though it is 25% farther out from the Sun (the orbit vizualised by JPL). This means that barring a strangely reflective surface, this object is larger than Pluto, possibly Mars-sized! The debate whether Pluto is a planet is likely to get rekindled by this discovery."
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Planet X Larger Than Pluto?

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  • by TripMaster Monkey ( 862126 ) * on Friday July 29, 2005 @10:25AM (#13194587)

    The link to the BBC story [] in the summary is broken.

    A functioning link can be found here [].

    So....the race is on to give this mysterious new planet a proper name! (Planet X is soooo Gen X...)

    Please post your ideas below.
  • by BlackCobra43 ( 596714 ) on Friday July 29, 2005 @10:25AM (#13194591)
    This rock I have in my backyard is a mountain.
    • Pluto is a planet? (Score:3, Insightful)

      by Quasar1999 ( 520073 )
      Yes, because we defined it as such. Right or wrong, we've defined it as a planet, therefore it is a planet. Stop debating and arguing over the status of the hunk of rock. It's not like if we define it as something else it will change or cease to physically exist. We are simply categorizing it. We could call it a comet, it fits into that category too.
      • by Anonym1ty ( 534715 ) on Friday July 29, 2005 @11:09AM (#13195026) Homepage Journal
        Here are My Definitions:

        Star: Any massive gaseous body emitting more energy due to nuclear fusion then by thermal radiation alone.

        Planet: Any body orbiting a star which is roughly spherical due to self-gravitation. (by this definition our solar system has 13 (14 now?) planets including Charon, Ceres, Sedna and Quaoar)

        Planetoid: Any body not orbiting a star which is roughly spherical due to self-gravitation. There is conjecture on this one. It once was just a synonym for asteroid, however now many call Ceres, Sedna and Quaoar planitoids or even minor planets, but I don't since they all meet my definition of a planet.

        Planetesimal: Any celestial object that does not have suffecient mass to form into a spherical shape. All asteroids and comets are planetesimals.

        Protoplanet: Any body in a solar nebula which is roughly spherical due to self-gravitation and does not produce energy by nuclear fusion.

        Moon: An object which is roughly spherical due to self-gravitation which orbits a planet. By this definition Phobos and Demos are not moons.

        Satellite: An object whose mass is not sufficent to form into a spherical shape which orbits a planet.

        Double-Planet: Two Planets of comparable mass orbiting one another in a system orbiting a star, who are both tidally coupled so as to always show the same face to each other in a system with a center of gravity that is not within either body. The center of gravity of the Earth/Moon system is about 2900 km or about 75% of the radius from the center of the Earth. Also, the Earth doesn't always show the same face to the moon. The Earth/Moon system is NOT a double-planet. The Pluto/Charon system is a double planet as they always show the same face to each other and the center of gravity of the Pluto/Charon system does not lay within either body.

        • by stevesliva ( 648202 ) on Friday July 29, 2005 @11:48AM (#13195408) Journal
          That's awesome!

          Could you now please define--with exclusivity--Lake, Pond, Brook, Stream, River, Sea, Gulf, Bay, Ocean, Hill, Mountain and Continent?

      • by Peyna ( 14792 ) on Friday July 29, 2005 @12:32PM (#13195811) Homepage
        So, should I throw away my Linnaeus classification of species and go back to using Aristotle's system of "air, land or water"?

        Or maybe we should throw out the periodic table of elements and just go back to earth, wind, fire, water? After all, we did categorize things that way at one time.

        As we learn more about the universe, we'll learn that our categorizations need and update to be more coherent and inclusive. While the original models might "work," as we add more variables to the system, there becomes the need to modify our system of classification.

        It's happened with elements and species, so why not large objects in the universe as well?
  • by Savantissimo ( 893682 ) on Friday July 29, 2005 @10:29AM (#13194622) Journal
    From my inexplicably rejected story submitted hours ago:

    The New Scientist reports []:
    On Thursday a new planet-sized object was found orbiting the Sun at a distance of between 35-51 AU (at different points in its orbit) and an inclination of 28 degrees to the plane of the inner planets. By comparison Pluto orbits at an average distance of 39 AU and an inclination if 17 degrees. (1 Astronomical Unit = the distance between the earth and the sun) If the object has a reflectivity similar to that of other Kuiper-belt bodies, it is approximately twice the size of Pluto. Jose-Luis Ortiz and his colleagues at Spain's Sierra Nevada Observatory discovered the object while reviewing data from 2003. The International Astronomical Union's Minor Planet Center (MPC) in Cambridge, Massachusetts verified the obsevations and designated the object 2003 EL61.
  • Lord John Whorfin: Where are we going?
    assembled Red Lectroids: PLANET TEN!
    LJW: When?
  • Of our Solar System? (Score:3, Interesting)

    by Alex P Keaton in da ( 882660 ) on Friday July 29, 2005 @10:29AM (#13194630) Homepage
    My understanding, and correct me if I am wrong please, is that Pluto was not formed at the same time as the rest of our solar system, that it was pulled in. Would it be the same for this additional planet? If so, there could be others out there with orbits that we didn't expect.
    Maybe I will move my telescope from being pointed at the neighbors shower and point it towards the sky.
    What I love about space, is that the more we discover, the more we have to learn.
  • by zenmojodaddy ( 754377 ) on Friday July 29, 2005 @10:30AM (#13194633)
    In order to avoid confusion as to whether Pluto is a planet, call the new planet Pluto and rename old Pluto something else, like Herbert The Cow. Or Mr Gazpacho. Or Hellish Creamcheese.

    It's Friday afternoon, and 5pm looks a LOOOONG way away. Can you tell?
  • A potential base for mining the Oort Cloud? I wonder if Wan is already there?
  • I for one (Score:4, Funny)

    by Ruprecht the Monkeyb ( 680597 ) * on Friday July 29, 2005 @10:31AM (#13194645)
    I, for one, welcome our new 2003-EL61ian overlords.

    Sorry...I've never gotten to do one of those before.
  • by wowbagger ( 69688 ) on Friday July 29, 2005 @10:31AM (#13194656) Homepage Journal
    OK, since most of the planets were named after Roman gods, here's a name for it:

    Bacchus [] - the party planet! Party all night - and it's ALWAYS night!
    • Perfect Name (Score:4, Interesting)

      by airship ( 242862 ) on Friday July 29, 2005 @01:37PM (#13196422) Homepage
      You nailed it with the 'night all the time' bit. But it's also:
      (a) In a more eccentric orbit than any other planet.
      (b) In a longer orbit than any other planet.
      (c) In a more inclined orbit than any other planet.
      So it's more eccentric, lazier, and tipsier than any other planet. Bacchus is therefore a perfect name for it.
      Oh, and since it's so cold there should be plenty of ice for the alcholic beverages. :)

    • Re:Name for it: (Score:4, Insightful)

      by xihr ( 556141 ) on Friday July 29, 2005 @03:33PM (#13197575) Homepage
      There's already an Apollo asteroid named Bacchus.
  • Interesting (Score:2, Funny)

    by Anonymous Coward
    A reflective surface you say?

    That's no moon, It's a discoball!

    *cue imperial march*
  • No wonder they keep getting it wrong! Not only do they have to keep track of Sedna, but Planet X too. And who knows how many more?

    Anyone get the feeling this solar system is getting a mite crowded?

    On the other hand, the repeat business can't be so shabby - just think how many of their best customers will need their charts recalculating...
  • by fruity_pebbles ( 568822 ) on Friday July 29, 2005 @10:35AM (#13194703)
    The TFA mentions two teams of scientists who found the object independently of each other. It doesn't say anything about discovery by an amateur astronomer.
  • I'm somewhat ignorant when it comes to astronomy like this, so if the following questions are ridiculous, just ignore me :)

    If the object is as big as the story says (With orbit that JPL predicted for it) why haven't we noticed it before? Given its (apparent) proximity to Pluto's orbit, wouldn't we have detected some sort of gravitational interaction?
    • by jscharla ( 144705 ) on Friday July 29, 2005 @10:50AM (#13194847)
      There are several reasons why this planet can't be detected gravitationally.
      1) Although it is roughly the same distance from the Sun as Pluto the inclination is about 10 degrees off so they are actually not close at all.
      2) Even if they were close, becuase the orbits are so slow at that distance (Pluto takes a few hundred years to orbit the sun) it would take a long time to notice pertubances in the orbit of Pluto.
      3) Even though this planet is twice the size of Pluto, it is still really really small. Pluto is smaller then our moon so at the distances we are talking here the interactions are going to be so small as to be completely unnoticable with our current technology.
    • I wouldn't expect any new planets to be found from gravitational perturbations, at least for a long while. (JPL's orbit is from the direct observations, not predicted from perturbations.)

      The orbital periods are long, and generally it takes at least one orbit of observations to say much about whether you have unwanted perturbations. Pluto has an orbital period of 248 years, and about a century of observations, so it's a bit too soon to say much about perturbations yet. Come back in a century.

      Plus, Plut
  • by The Famous Brett Wat ( 12688 ) on Friday July 29, 2005 @10:38AM (#13194735) Homepage Journal
    Excellent! A new source of Illudium Phosdex, no doubt. It will probably be over three hundred years before we can get there, though, by which time our supplies will be alarmingly low.
  • by Yeechang Lee ( 3429 ) * on Friday July 29, 2005 @10:39AM (#13194742) Homepage
    Pluto: Old and busted.
    Planet X: The new hotness!
  • by Ariane 6 ( 248505 ) on Friday July 29, 2005 @10:44AM (#13194796)
    It came in about seven o'clock last night...

    Hello MPML,

    Jose Luis Ortiz of Sierra Nevada Observatory asked me to forward his message. Actually he sent it to MPML today but it looks as if he is moderated and so his message is delayed. As this is pretty urgent, to give anyone interested the chance to do science on it, I hope my message gets relayed faster!

    Hi there,

    We found a very slowly moving object while carrying out a checking of some of our oldest images from the modest TNO survey that we started in 2002. []

    The object was very bright in our images (m_V~17.6!!) so we were able to precover it, and also recover it.

    According to our best orbit fit and using regular assumptions on phase angle correction, the H value es around 0.3. Unfortunately we do not know the geometric albedo but if below 0.25 (which is the case of all TNOs for which an albedo has been measured except Pluto), the object would be larger than Pluto. However, it may well happen that this object is abnormally bright (with a very high albedo), like Pluto. So, depending on the albedo, this object might be sort of a Pluto's brother or Pluto's father...

    This object is beyond Pluto and almost reachable by most amateurs, which is the reason why we write here!. It is observable right after sunset for a while at a reasonable elevation. Maybe some decent science can still come out of your observations.

    Enjoy it!.

    Our findings have been sent to the MPC, but the object has not received a provisional designation yet. Some ephemeris are given here:

    Ephems (geocentric) [Date, RA, Dec, r, delta, elongation, mag]:
    20050728.00000 13 21 50.208 +20 7 53.62 51.605 51.239 68.32 17.47
    20050729.00000 13 21 51.856 +20 7 14.56 51.619 51.239 67.49 17.47
    20050730.00000 13 21 53.576 +20 6 35.29 51.632 51.239 66.66 17.47
    20050731.00000 13 21 55.369 +20 5 55.81 51.646 51.238 65.84 17.47
    20050801.00000 13 21 57.233 +20 5 16.13 51.659 51.238 65.01 17.47
    20050802.00000 13 21 59.169 +20 4 36.26 51.672 51.238 64.19 17.47
    20050803.00000 13 22 1.176 +20 3 56.23 51.685 51.238 63.37 17.47
    20050804.00000 13 22 3.253 +20 3 16.02 51.698 51.238 62.55 17.47
    20050805.00000 13 22 5.401 +20 2 35.67 51.711 51.238 61.73 17.47
    20050806.00000 13 22 7.619 +20 1 55.17 51.723 51.238 60.92 17.47
    20050807.00000 13 22 9.906 +20 1 14.54 51.736 51.238 60.11 17.47
    20050808.00000 13 22 12.261 +20 0 33.79 51.748 51.238 59.29 17.47
    20050809.00000 13 22 14.685 +19 59 52.93 51.760 51.238 58.49 17.47
    20050810.00000 13 22 17.176 +19 59 11.97 51.772 51.237 57.68 17.47
    20050811.00000 13 22 19.734 +19 58 30.93 51.784 51.237 56.88 17.47

    The orbital elements are:

    OSNT11 Epoch 2005 July 29.0 TT = JDT 2453580.5
    M 197.97485 (2000.0) P Q
    n 0.00345428 Peri. 239.53682 +0.91285785 -0.07597426
    a 43.3408541 Node 121.89008 +0.13526717 +0.98332108
    e 0.1887862 Incl. 28.19395 -0.38521856 +0.16524998
    P 285.33 H 0.2 G 0.15 U 2

                          Jose-Luis Ortiz
                          Instituto de Astrofísica de Andalucía, CSIC
                          P.O.Box 3004. 18080 Granada. Spain.

    Jaime Nomen
    620 OAM
  • Hah (Score:3, Funny)

    by Sheepdot ( 211478 ) on Friday July 29, 2005 @10:46AM (#13194811) Journal
    Cue the Uranus jokes:
    "Speaking of size, what about Uranus?"
    "How can be possible comment on this new planet when we still have yet to send a probe to Uranus?"

    Some wise astronomers have tried to change the speech from "your anus" to "urine us" or "you're in us". Unfortunately the planet seems to just be plain doomed as far as American English pronounciation goes.
  • Doesn't add up (Score:3, Insightful)

    by exp(pi*sqrt(163)) ( 613870 ) on Friday July 29, 2005 @10:49AM (#13194841) Journal
    The published magnitude of Pluto is around 13-14. This thing is 25% further from the Sun (and Earth too) away but several times 'brighter' due to being more reflective and larger. That means it ought to appear brighter in the sky than Pluto. But it's reported as magnitude 17, which is quite a bit dimmer.
    • Re:Doesn't add up (Score:4, Informative)

      by badlikeacobra ( 903612 ) on Friday July 29, 2005 @11:23AM (#13195142)
      The magnitude (really, the visual magnitude) is a measure of how bright the object appears in the sky, not the absolute brightness of the object. Think of it this way. The Sun has a magnitude of -26.7. Vega has a magnitude of 0. Vega is a much brighter star than the sun, but because of the differing distances from the Earth (and therefore, the observer) Vega appears much dimmer than the Sun.

      You are thinking of the absolute magnitude. Typically, absolute mangitude is refered to as such while the visual magnitude is refered to as magnitude.
  • by ZOmegaZ ( 687142 ) on Friday July 29, 2005 @10:49AM (#13194844) Homepage
    When's the first astrologer going to sue because the discovery of this planet has deformed her horoscope?
  • by Rob Carr ( 780861 ) on Friday July 29, 2005 @10:50AM (#13194851) Homepage Journal
    Astronomers were using too short a time span between pictures for them to see the change in position of something 51 AU out from the sun. The angle of the orbit to the ecliptic made it harder to find, too.

    Since this was found so easily, one has to wonder just how many of them there are out there. This might be only the first of many.

    This, by the way, is an excellent reason to call these things TNOs (Trans-Neptunian Objects). Who wants to memorize the 85 planets of our solar system?

  • by jurt1235 ( 834677 ) on Friday July 29, 2005 @10:53AM (#13194878) Homepage
    Discovered by an amateur, not seen before with all hightech equipment, strangely reflectant surface almost rendering it invisible?? Round (asuming it is a ballshaped object): It is a super borg sphere!! Run to the closet and get your bathlets! They can not fight against that!

    Ok, the other possibility: Independence day...

    And the last option: It is a cloacked deathstar!
  • Not Planet X (Score:3, Informative)

    by brownpau ( 639342 ) on Friday July 29, 2005 @11:02AM (#13194959) Homepage
    Note that this is not Sedna [], and this is not Nibiru [].
  • New Name? (Score:4, Funny)

    by jav1231 ( 539129 ) on Friday July 29, 2005 @11:04AM (#13194976)
    Someone suggested moving Uranus' name to this planet. I think there should be a contest! Possible new names:
    I mean, why not. It's frigid and inaccessible to those who want to "study" it most!
  • by Gorimek ( 61128 ) on Friday July 29, 2005 @11:10AM (#13195034) Homepage
    It's just Big Boned!
  • Pioneer (Score:5, Interesting)

    by guitaristx ( 791223 ) on Friday July 29, 2005 @11:14AM (#13195072) Journal
    Could this large object out there possibly be responsible for the Pioneer Anomaly?
    • Re:Pioneer (Score:4, Informative)

      by tommy_teardrop ( 228273 ) on Friday July 29, 2005 @12:20PM (#13195714)
      In a word - No.

      Both Pioneer Spacecraft (as well as Voyager) measure the anomaly, and they are moving away from the Sun in different directions. A distant object has been ruled out as a potential source of the effect, since to produce a slowing of all the spacecraft you need a force acting towards the sun. Whatever is causing them to slow down, it's not a solar system body too far out for us to see.
  • by rwllama ( 587787 ) on Friday July 29, 2005 @11:42AM (#13195349)
    Amongst professional astronomers (which includes me), Pluto is generally not considered a planet. It is the largest member of the Kuiper Belt. It is historical accident that Pluto was discovered almost 50 years before the second Kuiper Belt object, Charon, in 1978. The third KBO was found in 1993. Since then, over 700 other KBOs have been found, several of which rival Pluto in size.

    What we have here is one that could be larger than Pluto. This is not unexpected, but has been predicted ever since we started discovering KBOs in serious numbers. There is always a distribution of sizes, and Pluto lies near the upper end, but it is unlikely that it is the largest, and even less likely that it would be distinctly larger than the rest of the population.

    To call Pluto a planet is to create a category of "ice planets" which contains only one object. That is scientifically silly. To call it a Kuiper Belt Object fits it in with a family of other objects whose characteristics in composition, orbit size, orbit shape, orbit inclination, companions, etc are shared amongst the group. That is a scientific classification.

    The solar system does not contain "the Sun and
    9 planets" as so many of us incorrectly learned. Rather, it contains 6 families: a star, the rocky planets, the asteroid belt, the gas giant planets, the Kuiper belt, and the Oort cloud. Each of these families shares common characteristics that are the basis for this classification. Pluto, and this new discovery,
    fit squarely in the Kuiper belt.

    Now for the truth about planets. The IAU, which
    governs these things, has no official definition of what constitutes a planet. There is a reasonable upper limit in mass (i.e., not so larger as to create fusion at it core), but there is no lower limit. Most astronomers would say that a reasonable idea would be large enough for gravity to make it spherical (or close to, like Earth). However, then other KBOs and asteroids qualify as planets. You simply can't come up with a rigorous definition that includes Pluto and excludes the others unless you work customize your definition in a manner that is not scientific.

    This will not be the last big KBO. There will be several more. These are exciting times as we discover more and more about our own backyard.
    • The solar system does not contain "the Sun and 9 planets" as so many of us incorrectly learned. Rather, it contains 6 families: a star, the rocky planets, the asteroid belt, the gas giant planets, the Kuiper belt, and the Oort cloud.

      Can't remember who it was first said it, but the best classification I ever read was:

      "The Solar System contains the Sun, Jupiter, and assorted debris."

  • by Rocketboy ( 32971 ) on Friday July 29, 2005 @11:45AM (#13195386) has a clarifying article at _object.html []. 1. It apparently isn't larger than Pluto, regardless of how reflective its surface might be. It's mass is only about a third of Pluto. 2. It has a very small moon. 3. It was *just* too dim to have been found by Clyde Tombaugh, the discoverer of Pluto.

  • by nova_planitia ( 444881 ) on Friday July 29, 2005 @11:53AM (#13195468) Homepage
    I made a heck of a typo when I submitted this story, 2005 EL61 is a about roughly eight times fainter than Pluto, not brighter. The latest information is that this object is more likely to be in the ballpark of Pluto's size and not bigger. This object also does not appear to be the same 17th magnitude outer solar system object observed by the Gemini telescope earlier this year that was going to be "announced" in September at the DPS meeting. So it looks like a few of these guys may be out there.
  • Rupert! (Score:3, Funny)

    by Klowner ( 145731 ) on Friday July 29, 2005 @11:53AM (#13195475) Homepage
    They loooove our television there, and our mail-order furniture.
  • Pluto and 2003 EL61 (Score:4, Interesting)

    by Autonomous Crowhard ( 205058 ) on Friday July 29, 2005 @12:54PM (#13196044)
    Warning: everything below assumes that the JPL app and orbital estimates are correct.

    There does seem to be a point where Pluto's and EL61's orbits get rather close. I wonder if this could point to a potential common origin? Maybe Something Else (tm) passed by and flung 2003 El61 out of the little triad. (I would doubt Pluto and Charon would be the ones tossed because the odds of them staying together would be low) The distance between the orbits might be explained by precession.

    Unfortunately the Java app only covers from Jan 1, 1600-2200 so I couldn't test this theory. Can someone else play with the app and look into the distant past for a near miss?

  • by xihr ( 556141 ) on Friday July 29, 2005 @03:40PM (#13197646) Homepage

    Planet X was thought to be a very large planet, responsible for causing apparent perturbations we were seeing in the orbit of Uranus and Neptune. When Voyager II flew by these planets and got refined measurements of their masses, the discrepancies went away. We now know that the revised data shows no perturbations, putting severe limits on very large objects to very great distances. That is, there is no Planet X, and there never was.

    There are likely all sorts of Pluto-sized objects out there, though. So finding another one is not surprising. There's nothing special about the mass of Pluto, and so some Kuiperoids will be around the same mass, and some will be more (though probably not too many). Thus, this discovery is nothing very surprising. You'd expect to find Kuiperoids more massive than Pluto out there.

    As for reigniting the "controversy" about Pluto's planetary status, probably not. There's really not much controversy here. The IAU does not have and never has had an objective definition of the word planet that Pluto succeeds or fails in meeting the criteria for. A planet is literally what we point to and say, "That's a planet." The terms are made up by us, after all; do you think Pluto cares what it's called? Do you think that somehow further enhances the study of it, knowing that it's in this classification bin but not this one?

    There have been a few serious astronomers suggesting conferring dual classification -- as both a planet and an asteroid/Kuiperoid -- to Pluto. The official proposal was never about demotion. Talk at length about removing planetary status from Pluto has largely been taking place in the popular press and by amateurs. Most actual astronomers don't care, because it doesn't matter what name you give something.

  • Another one... (Score:5, Informative)

    by Ariane 6 ( 248505 ) on Friday July 29, 2005 @04:31PM (#13198108)
    Just when you thought that this couldn't be bigger news, Ron Baalke at JPL has pointed out that another object, 2003 UB313, resides at 96 AU and has a diameter from 4400 km to 9900 km, assuming its albedo is between 0.05 and 0.25. Though the inclination is a bit weird (44 degrees), this may be considered planet-sized. [] []
  • by pyrrhonist ( 701154 ) on Friday July 29, 2005 @05:17PM (#13198475)
    Okay, so after observations by Mike Brown (one of the discoverers of Sedna [] and a member of the team that was researching 2003 EL61 [] when the Ortiz team announced it) this appears to be KBO smaller than Pluto.

    However, there's an even more interesting thing that Mike Brown has on his page, called 2003 UB313 [] (a.k.a. "Lila").

The most important early product on the way to developing a good product is an imperfect version.