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The Sun's 10th Planet... Sedna?
Posted by
CmdrTaco
on Sun Mar 14, 2004 12:26 PM
from the well-that-remains-to-be-seen dept.
from the well-that-remains-to-be-seen dept.
dsanfte writes "While NASA remains intentionally vague, promising only a news conference Monday, The Australian has the details. The new planet, dubbed Sedna after the Inuit goddess of the sea, is 3 billion km further from the sun than Pluto, and is slightly smaller at 2000km in diameter. This discovery has apparently reignited the debate as to how big a solar object must be in order to qualify as a 'planet', but it is significant nonetheless."
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First Oort Cloud Object May Have Been Discovered 110 comments
SpuriousLogic alerts us to the discovery of what may be the first object ever discovered from the inner edge of the Oort cloud. 2006 SQ372 was found on images from the Sloan Digital Sky Survey. Its discoverers theorize that this comet-like object and the planetoid Sedna, first spotted in 2003, might be Oort denizens. Sedna is in a stable orbit but 2006 SQ372 has been perturbed by the gravity of Uranus and/or Neptune, simulations suggest, so its orbital history is unknowable. 2006 SQ372 will travel out to 1,600 AU on this orbit, making it the most distant solar-system object yet found. The Oort cloud is believed to extend ten times that far, or about a quarter of a light-year. "Theoretical models of the formation of the Oort Cloud predict that it should also host a massive inner part, but comets from this region never make it near Earth. To see the long-period comets from the inner region of the Oort Cloud requires observing comets whose orbits always stay well outside Saturn's orbit — like 2006 SQ372."
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A lot of astronomers don't want to count Pluto (Score:5, Interesting)
Re:A lot of astronomers don't want to count Pluto (Score:5, Funny)
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Funny)
Parent
What about atmosphere? (Score:5, Interesting)
Pluto has an atmosphere [spacetoday.net], so it's a planet. What about Sedna? Does anyone know, or must we wait until Monday?
Parent
Re:What about atmosphere? (Score:5, Interesting)
Parent
Picture of new planet: (Score:5, Funny)
Here----> .
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Informative)
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Interesting)
We should use this for the demarkation between "asteroid" and "planet." An asteroid is one big chunk of rock. A planet is a bunch of little rocks held together by their own gravity.
If Pluto primarily orbits the sun and it's dense enough to hold on to an atmosphere from time to time, why shouldn't it be considered a planet?
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Insightful)
Frankly, I don't understand this line of reasoning. Why does it matter, with regards to whether something is a "planet" or not, whether that thing is bigger than, for example, our moon?
And "asteroid"? Pluto is far, far larger than anything currently considered an "asteroid".
Jupiter and Saturn both have moons that are bigger than Mercury. Do you not consider Mercury to be a "planet", either?
What if Jupiter had a moon bigger than Earth? That's not unimaginable; would Earth then not be a "planet"? In fact, would then nothing be a "planet" except Jupiter, Saturn, Uranus and Neptune?
I frankly don't see what's wrong with (something like) a "planet" being a non-star that's orbiting (directly) around a star. Sure, that makes for some seriously small "planets" relative to what we're used to, but at least it's not an arbitrary and useless definition like (no offense) yours.
And anyway, if you want to add back in your preferred amount of arbitraryness, you can always start referring to "major planets", "minor planets", and so forth.
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Insightful)
I agree with parent that in this case size really doesn't matter: it's all in how you use what you got.
Historically, Neptune was discovered because it was perturbing Uranus' orbit: its existence was theorized long before it was directly observed. Similarly, Pluto was discovered because it was found that Neptune alone was not sufficient to account for all of Uranus' irregularity. While Pluto isn't very big, its size and orbit are such that it definitely affects the other planets.
In practice then, what we have actually used to distinguish a planet like Pluto from a large body that is not a planet, like Chiron (roughly as big, discovered 1977), is whether the object interacts in a measurable way with known planets. If it does, then accord it planet status because it is clearly part of the planetary system.
In view of this, the new discovery is probably not a planet, unless it has a weird orbit like Pluto and would account for some of the remaining difference between planetary observations and expectations.
But what do I know? IANAA.
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Interesting)
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Informative)
IMO, Pluto should [shouldn't?] be labeled an asteroid since it's smaller than even our own moon [wikipedia.org].
An interesting point, though to be fair, its an arbitrary cutoff. There are moons elswhere in our solar system larger than Mercury, which is indisputably a planet, for example. Also its worth pointing out that our moon is large enough that it and Earth are sometimes called a double planet. Consider this, Luna does not orbit Earth as near the equator as is usual among most other moons. Also, peculiar to all 138 known moons with the exception of Charon, it possesses an orbit where the effect of the Sun's gravity is greater than that of Earth's. Without their host planets, they would float off, wheareas the moon would continue orbiting the sun quite contently.Parent
Escape velocity (Score:5, Informative)
I have been interested in Astronomy since I was about six years old. Just over forty years. I have heard what you suggest before -- but only in the last few years. And I don't understand it any more this time than I did on the earlier occasions.
Frankly, I strongly suspect it is a false factoid, like that the internet was built to survive a Nuclear War. I strongly suspect it is a bullshit meme that keep being repeated because it sounds cool, but is completely false.
Pray explain what you mean when you say the other 138 moons would float off ?
I am trying to do the "thought experiment" of silently, quietly erasing the principals of those moons, mass and all. I am finding this difficult to do. I don't believe there is any way this could occur, in our Universe.
So, instead I imagined doing something to accelerate a moon, any moon, to the escape velocity of its principal. What happens then? Well, the object accelerated to just beyond a planet's escape velocity will assume an orbit very similar to that of the Planet it just escaped from. Sometime in the last couple of years ago there was a flap about a small object [slashdot.org] that seemed to have been temporarily captured in the Earth-Moon system. But it turned out to be NASA space debris. It appeared to be the discarded upper stage of an Apollo moon shot.
Parent
Re:A lot of astronomers don't want to count Pluto (Score:5, Insightful)
Why does there have to be one? Man's tendency is to compartmentalize things, to make sure everything has a name and that name is unambiguous. Problem is, nature doesn't cooperate. There are always going to be intermediate forms, so there are never going to be definitions that aren't arbitrary.
Same thing applies to species. The nice simple definition "if it can interbreed, its the same species" doesn't always work, and there is no reasonable definition that covers all cases and removes ambiguity.
Parent
A decision based on Science, or Politics? (Score:5, Interesting)
Did you know that in 1998 Senator Patrick Leahy, of Vermont, got his State's largest Lake, Lake Champlain, to be reclassified as the 6th Great Lake? [dencities.com] At least as far as the awarding of researh grants. Being considered a "Great Lake" made the academic institutions in his constituency eligible to apply for certain research grants.
There is talk of sending a probe to Pluto. Is it possible that it is easier to sell a probe to "planet Pluto" than to send one to Kuiper-belt object Pluto?
I remember, back in the days when I tuned in to debates as to which newsgroups should be created, the big debate as to whether a new group should be talk.acquaria, rec.acquaria or sci.acquaria.
In Leahy's defence, these were environmental research grants, and I should probably assume he added this line to the bill to protect his constituent's natural environment -- not for the petty partisan purposes.
Parent
Woop de fucking do! (Score:5, Funny)
Re:Woop de fucking do! (Score:5, Funny)
Parent
Re:Woop de fucking do! (Score:5, Interesting)
Ten Planets? You haven't been keeping up with here astrology has been going the last twenty-fove years. I know astrologers who use twenty planets, most of which are imaginary. [ Dutch School of Astrology. Germans School of Astrology. The Planets of Alice Bailey, and related flakes.]
This, of course, ignores the two hundred or so asteroids which new age astrologers use. And don't forget the plethora of comets, meteor showers, deep space objects, and other things that may, or may not exist.
And to be sure that you haven't forgotten anything, there are umpteen "Arabic Parts", Midpoints, Orbs, harmonics, ( or something like that) etc.
In short, roughly 10^8 objects that no self-respecting astrologer would omit, if one believes in the validity of all the books on astrology that have been published.
Parent
Re:Woop de fucking do! (Score:5, Insightful)
Bullshit. If it's accurate, then you could come up with a test to prove it. You could take astrological predictions for an individual based upon his house and compare them with random predictions. These could then be compared for statistical validity, proving once and for all that astrology is accurate.
Wow, if only someone would take the time to perform tests like these. Maybe someone could even make a contest to offer money to anyone who could prove a fantastic claim like "astrology is accurate". [randi.org]
Get it through your skull. It's PROVEN TO BE bullshit. It's always been bullshit, and it will always be bullshit. I've had close dealings with astrologists. I know how some of what they say can seem to be more than just coincidence, but that's all it is -- coincidence and psychology. It's got nothing to do with anyone's "house" or "fate". It's all just bullshit. Don't be a sucker.
Parent
Re:Woop de fucking do! (Score:5, Interesting)
Yeah, can't imagine a worse name, really. Backwards-spelled stuff is pure gold in the conspiracy community.
Parent
Astrology = Syncretic Religion (Score:5, Insightful)
Astrology doesn't work that way.
Astrology is syncretic religion [google.com] -- it readily (and inevitably) incorporates new influences.
Like an amoeba, astrology engulfs everything it touches.
In this sense, astrology is rather like paranoia: everything pertains, everything is part of the Big Picture.
Sedna won't fuck up astrology. On the contrary, astrologers will eagerly seize on the idea of this new planet, treating Sedna as one more vacuole in the amoeba.
-kgj
Parent
Re:Woop de fucking do! (Score:5, Funny)
Parent
I wonder what is so important.... (Score:5, Interesting)
--
Real-time deal updates [dealsites.net]
Re:I wonder what is so important.... (Score:5, Interesting)
The reason being that news outlets are not at full capacity during the weekends, so any news announced over the weekend won't get as much coverage. If NASA announced the news today, it will be covered on the Sunday evening news, and never again since that piece of news was already done, even when not many saw it.
You can notice this practice when someone famous dies over a weekend. There will be an immediate announcement saying that the person is missing or very ill or something of the sort, then make the announcement on Monday.
Parent
Re:I wonder what is so important.... (Score:5, Funny)
It's the monthly bug-report announcement. "A local root vulnerability has been found in the astrology community. NASA rates it as non-critical"
Parent
whew! (Score:5, Funny)
Re:whew! (Score:5, Funny)
Parent
for comparison purposes: (Score:5, Informative)
http://www.windows.ucar.edu/tour/link=/pluto/stat
It's a Kuiper object... (Score:5, Insightful)
Whether Pluto is 'really' a planet or just a big Kuiper object seems to be a silly argument. Even if it's not justifiable, we'll call Pluto a planet out of tradition.
Re:It's a Kuiper object... (Score:5, Informative)
Sedna is over 4 times the size (volume) of Quaoar.
Whether it's a planet is a silly argument, but even so, "we already have Quaoar" is really irrelevant.
Parent
Planet is not a useful category. (Score:5, Interesting)
Parent
Re:It's a Kuiper object... (Score:5, Informative)
I think ultimately the question is whether there is a single continuous "initial mass function" of isolated objects or not. The best idea as to how stars acquire their initial mass is that turbulence in the interstellar medium, which exists on all scales, establishes a power-law distribution of initial masses. Every once in a while, you get a very strong shock which passes by inside a giant molecular cloud and forces the collapse of a large region which then goes on to form a massive star. But more typically, you form stars more like our sun. And just as rare as massive collapses are very small mass ones which go on to form isolated brown dwarfs and free-floating planets. If this model holds up to be true, then we are all mincing words in our definitions of isolated systems, since they are all manifestations of the same universal formation process.
However, to avoid the difficult question of formation mechanisms, an IAU working group of some of the most respected people in the field established a working definition [ciw.edu] to define by fiat what it means to be a brown dwarf, and a planet. Extrasolar "planets" are those objects orbiting a star which are beneath the deteurium-burning limit -- regardless of how they are formed. "Brown dwarfs" are defined to be those which burn deuterium but not lithium, and "sub-brown dwarfs" (NOT free-floating planets!) are defined to be those isolated objects which do not burn deuterium. Even the working group itself admitted that this definition was not satisfying to a single member of the group, and so it is likely it will be replaced at a later time with something more physically-motivated. The "planet/planetismal/KBO" distinction was pushed back to our own solar system, since it will be some time before anyone sees anything that small in another system.
Also of interest is the following link, which gives a history of previous claims for additional planetary members of our solar system : SEDS [arizona.edu].
Parent
What happened to the naming convetion? (Score:5, Interesting)
And that's before you start getting slightly obscure ones like Janus, Bacchus (Or Liber), Fanus, Quirinus, Pomona, or Vertumnus.
Re:What happened to the naming convetion? (Score:5, Interesting)
Now that Roman mythology isn't really considered religion (outside of Berkeley) it can be a nice tradition. I mean, it's not lik the Inuit have really contributed to Western Culture except for, I guess, hockey and lacrosse.
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Inuit Contributions (Score:5, Informative)
Inuit inventions include snowshoes, toboggans, dogsleds, kayaks, toggle harpoons, and various other tools for hunting and travelling in the North as well as snow and ice civil engineering techniques. Pretty impressive, I'd say, for a culture with almost no wood, rock, or metal. They've probably contributed as much as any other non-Eurasian colonialised culture, and they make some really cool art.
Parent
Re:What happened to the naming convetion? (Score:5, Informative)
Parent
There could be a lot of stuff out there (Score:5, Interesting)
The really interesting question is, what is the mass distribution ? (I.e., how does the number of objects scale with their mass ?) This is basically unconstrained by real data. All such cosmic mass distributions are steep, but many (for example, planets in the Solar System, Asteroids in the Asteroid belt) are dominated by the most massive bodies.
If this holds true in the Oort cloud, in particular, there could be some pretty big objects. Even a Jupiter sized object might be able to hide from the Infrared surveys (the best way of detecting such an object).
10th planet is more fun so it is in (Score:5, Interesting)
Anyway something 2000km in diameter is hardly small. Aren't astoroids that could kill earth just a couple of kilometers accross?
Anyway excluding it is sizeist. Can't have that. If you are going to classify keep it simple. Object larger then a rock orbetting the sun and being close to round. I think that is what most people consider a planet.
So welcome sedna.
Not a problem yet (Score:5, Interesting)
Everyone wants to push this off as long as possible, so if the new object is really smaller than Pluto, they'll breathe a sigh of relief and go on with things as they are.
on being a planet or something less... (Score:5, Insightful)
My former advisor here at UC Berkeley, Gibor Basri, has a neat way of discriminating between planets and the lesser (comets, asteroids, etc.). His idea is that if the object has enough self-gravity to force it into a spherical shape, it's a planet... if it doesn't (like Mars' "moons"), it's something less.
Here's a snipet:
read on for his full article [berkeley.edu].
Re:How could (Score:5, Insightful)
Parent
Re:How could (Score:5, Informative)
The binoculars also limit or eliminate local vision while in use, obscuring the approach of your spouse/mother and a disapproving hand. . .:)
Parent
Re:How could (Score:5, Insightful)
Parent
Re:Back to grade school for retraining... (Score:5, Informative)
Of course, there's debate as to whether Pluto-Charon is a planet with a moon, or a double planet...
- Thomas;
Parent
Re:Back to grade school for retraining... (Score:5, Interesting)
If both focal points for the orbit are contained within the volume of one body, or if one focal point is contained within the volume of one body and the other focal point outside of both bodies, then the smaller object is a moon of the larger.
If both focal points are outside the volume of both bodies, or if one focal point is within the volume of one body and the other focal point within the other body, then the pair of objects should be considered a double planet.
So Pluto/Charon, following this reasoning, should be considered a double planet.
Parent
Umm...Mars? (Score:5, Insightful)
Umm...what? The past few months have been *spectacularly* exciting from a space point of view. We have two probes that successfully landed on Mars and have found strong evidence that Mars had liquid brine at one point. We have a ton of pictures from the surface to look at, and are expecting tons of findings, papers, and theories based on probe data that's been returned.
And while, yes, the classification may not be interesting, the fact that we discovered a new, sizeable chunk of matter in our solar system is not small stuff either.
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Re:I claim it (Score:5, Funny)
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Re:What, no more Roman gods? (Score:5, Interesting)
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The Inuit myth of Sedna (Score:5, Interesting)
Sedna isn't actually a creator goddess -- she was born mortal, and became a goddess when the spirits of the air and the moon decided to reward her for her suffering in her mortal life, as she was drowning. Two accounts of the Sedna myth may be found here [hvgb.net] and here [inuitgallery.com].
In any event, aren't you glad that they're naming it Sedna, and not Uinigumasuittuq?
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Bode's Law (Score:5, Interesting)
According to my hung over calculations Sedna is 67 AUs out, which is not that far off from the 77.6 that Bode predicts, but not really close either.
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