Sedna May Have A Moon

ArrayIndexOutOfBound writes "The newly found planet Sedna may have a moon. It appears that most astronomers argue that Sedna is only another proof that neither Sedna nor Pluto are really planets. Interestingly, the planet has been found by an 'automated sky survey telescope'..." SYSS Mouse points to a NASA page with more information about "our potential 10th planet. ... It is 130 billion miles away from the sun (900 times Earth's distance from the sun) and has a 10,500 years orbit, compared to Pluto's 230 years around the sun."

Comments

Value out of bounds

[shadowbearer]

Um, the article said it was 13 billion miles out, not 130 billion (now discovering something that size 130 billion miles out would be a real hell of an achievement :)

There's some theorizing that this may be part of the inner Oort shell; I think it more likely that at that distance it's an outer member of the Kuiper bodies.

Given the highly elliptical orbit, it's size, and it's apparently odd surface color, it's also possible that it's a body captured by the sun some hundreds of millions or billions of years ago. Now *that'd* be neat.

SB

Re:Value out of bounds

[Pumpernickle]

That's true, but not entirely.

At its most distant, Sedna is 130 billion km (84 billion miles) from the Sun, which is 900 times Earth's solar distance (149 million km or 93 million miles).

They were just quoting the wrong part of the article in the wrong place.

Re:Value out of bounds

[shadowbearer]

Thank you, I missed the most distant part. Seeing "130 billion km" and thinking "detection at" made my brain stop functioning for a instant, I guess :)

I was just thinking; we detected Sedna at nearly it's closest part in it's orbit (and probably wouldn't have detected it as easily or at all if it had been much further out). Is it just me, or that say something about the statistical distribution of larger bodies at those distances? Either that or it's a helluva coincidence.

(Maybe not, but I'm too work-wiped to do the math right now)

SB

Re:Value out of bounds

[IamNotWitchboy]

From an article about Sedna featured on Scotsman News International appeared on Google News which displays the following paragraph:

Dr Michael Brown, an astronomer at the California Institute of Technology in Pasadena, who led the NASA-funded research, said: "The sun appears so small from that distance that you could completely block it out with the head of a pin."

The temperature on Sedna never rises above -400C, making it the coldest known object in the solar system.

It must be an extremly bizarre planet because its temperature is WAY below the absolute zero which is known to be at -273 C

Re:Value out of bounds

[phyrestang]

I should think that it was a typo. They probably meant -400F, as absolute zero is -459 Fahrenheit.

Incorrect links

[Rewbob]

The first link is about an object named "2004 DW". The second link is about Sedna (previous known as 2003 VB12).

The newly found moon is orbiting Sedna, NOT 2004 DW.
The links in the slashdot article are misleading.

Re:Incorrect links

[kalidasa]

They haven't actually *found* a moon around Sedna yet, they're just guessing there's one there because the rotational period is very slow, suggesting that it might have a relationship with a satellite similar to Pluto's with Charon. 2004 DW is another big object (TNO).

That's no moon!

[Anonymous Coward]

It's a space station.

Sedna has a moon...

[k4_pacific]

...therefore it is a planet.

Per Webster's:

moon, n. a natural satellite of a planet

So there.

Re:Sedna has a moon...

[adeyadey]

Many (non-planet) Asteroids have moons or satellites in orbit about them..

Re:Sedna has a moon...

[p4ul13]

All moons are satelites, not all satelites are moons. OUR moon is called "Luna", just like we've given names to the moons of all the others we've discovered.

You rarely hear our moon refered to by its actual name because its pretty obvious which one you're talking about when you say "Moon". Same thing with our resident star / sun. Its name on its birth certificate reads "Sol" and our very own Earth is often known as "Terra".

Oh, and let's not forget that our solar system isn't named just "The Solar System"; it's name is "Stanley".

Re:It's too far out to be an SKBO

[shadowbearer]

From the same page:

Is Sedna an Oort Cloud Comet?
From the Classical Oort Cloud - no. The latter consists of objects whose orbits are so large (50,000 AU) that passing stars and galactic tides can alter their properties. Sedna doesn't travel very far out (1000 AU) and is effectively immune to external forces. Also, the inclinations of both Sedna and 2000 CR105 are small (12 and 23 degrees, respectively). These objects know where the plane of the solar system lies. Oort Cloud orbits are random with inclinations all the way up to 180 degrees.

So What Is It?
Sedna could be a member of a substantial population of bodies trapped between the Kuiper Belt and Oort Cloud. These would have been emplaced at early times and unseen until recently. 2000 CR105 and Sedna are "just the tip of the iceberg", as they say. The scientific interest lies in how these objects had their perihelia lifted out of the planetary region.

So it's really on the fuzzy boundary between the two, but closer to the Kuiper belt than to traditional Oort cloud objects. I'd bet there are a lot more objects this close to this size out there. (a hunch, but we're only beginning to explore that region).

Fascinating. I wonder if we'll ever trace it's orbit back far enough to determine whether it was flung out of the inner system or formed elsewhere. Doubtful. In any case, it's good to know there are objects this size out in that region, just in case we ever *really* need to flee the inner system (tongue in cheek, partially; reading the news gives me that feeling often nowadays..)

SB

An amazing eccentricity

[Evil Pete]

I thought it was a misprint in the article, so I went to Nature news. Sure enough at perihelion it is 13 billion km from the Sun an at aphelion it is 130 billion km. Wow, usually you only see orbits that eccentric with comets. Which makes it seem more like a captured object rather than one that formed in orbit. Wonder white kind of perturbing influence it has on comets in the Kuiper Belt, admittedly its small and in a very big volume ... still ...

Mission to Sedna

[adeyadey]

I understand that the "pluto - new horizons" mission, due hopefully for launch in 2006 (http://pluto.jhuapl.edu/mission.htm) is looking for possible KB targets after getting to Pluto in 2015. I wonder if the planetary line-up would allow one of those targets to be Sedna? (prob not, but you could be lucky..)

Is there a chart anywhere that gives the location of all these various objects in relation to the solar system, at any given time?

There is another deep-space mission in the pipeline (ion-drive) to the heliopause and beyond - is Sedna positioned toward the heliopause?

By the way, Sedna is another good reason to upgrade and keep Hubble going..

Re:Mission to Sedna

[CheshireCatCO]

Yes, but if Voyager 2 were to encounter Sedna now, it wouldn't do a bit of good. It doesn't have nearly enough power to collect any useful data, let alone return it. Both Voyagers and Pioneers 10 and 11 have been essentially comatose for many years now: they're alive, but just barely.

Planet X

[DigiShaman]

Oh my GOD!! It's Planet X...quick, someone call Art Bell. The end of the world as at hand...Aarrrggghhhhhhhhaaaaaa!!!

Ya ya, I'm being silly.

Re:Planet X

[RobertB-DC]

Ya ya, I'm being silly.

You're being silly, but the tin-foil hat crowd is going to have a field day with this baby. Consider the links that they'll find to their planet-killing Nemesis object:

* Highly eccentric orbit with a period ~10k years. They'll make up a mass extinction event to match the planetoid's period, you watch.

* According to this article, Sedna is the reddest object found in the solar system except for Mars. Watch the Nemesisians find deep significance in this fact -- we could start a pool to guess when they start calling it "blood red".

* In the "just enough facts to be dangerous" department, they'll point out that its size can't be determined directly -- that it depends on assumptions about the planet's albedo. If it's darker than expected, then it'll be bigger than expected. Ergo, the scientists are conspiring (as usual) to make it smaller than Pluto. Their "scientific" conclusion: it's the brown dwarf companion to Sol that they've been predicting all along.

Interestingly (to me at least), I submitted this story as soon as I saw it... and it was rejected almost as quickly. I suspect the editors were looking for a submission without tinfoil hat references -- a laudable goal. But even if we Slashdotters are gathered to discuss the real science, our less-informed Internet brethren haven't had much to talk about since the Martians quit shooting down spacecraft...

Go to the source Luke.

[I am Jack's username]

> I thought it was a misprint in the article, so
> I went to Nature news.

I've been writing for wikipedia about TNOs, and so I've checked links to articles at CNN, WashPost, BBC, etc.. The commercial news companies get so much wrong it's scary.

In the article you linked to at Nature.com it says "The Spitzer telescope has spied Sedna." and "The Spitzer and Hubble space telescopes later confirmed the find.". Co-discover Mike Brown however, clearly states that they "used the 30 meter diameter IRAM telscope, and in collaboration with John Stansberry at the University of Arizona and Bill Reach at the Spitzer Science Certer, we used the Spitzer Space Telescope. Sedna was too small to be detected in either."

Avoid the corporate media and go to the source, or lacking that know that the news companies exist to make money - not to report the facts.

Intermingling of fact and definition

[dpbsmith]

It is always interesting to watch science being created. In this case, you see the nexus of a) actual facts (the discovery of a celestial object) with b) the completely artificial process of trying to name and classify things.

Is Sedna "really" a planet? Sedna is what it is, of the size and composition that it is, in the orbit that it is in. Sedna does not know or care whether it is "really" a planet or a minor planet or a dwarf planet or a comet.

Naming disputes are interesting because they always reflect the relative influence and authority of the people giving the names. Not being an astronomer, I can't identify who exactly is jockeying for positioning. Naming and classifying are part of the prescientific process. In a few decades we will probably have a better idea of how real these groupings of similar objects really are.

Re:Intermingling of fact and definition

[CheshireCatCO]

I am an astronomer and as far as I know, none of us is trying to get this beast classified as a (major) planet. It's most likely (by anyone's definition) an Inner Oort Cloud object. That more than adequately describes it in relation to the rest of the solar system. The whole idea of there being a controversy is more of a media/NASA press-office construction than a reality.

And while on one level you're right, names are artifical, on another you miss the point of naming entirely. What we call things affect how we consider and perceive those things. Language shapes our thoughts, after all. So classification isn't "prescience" it's a part of the scientific process. Classifying living organisms was the first step towards understanding their relation and then their evolution. Classifying celestial objects plays the same role. It may not be as scientific sounding as producing numbers and plots, but it's important none the less.

Re:Intermingling of fact and definition

[CheshireCatCO]

Kuiper Belt Objects are about half and half rock and ice, actually. Beyond about 5 AU you expect icey bodies, since hydrogen compounds are way more common than metals and silicates. (The only trouble being that it has to be cool enough for them to condense.)

And, yes, there has long been hypothesized to be (based on dynamical models and, I believe, comet distributions) an Inner and Outer Oort Cloud.
There is some thought that the Inner Oort Cloud should sort of merge with the Edgeworth-Kuiper Belt, although that's mostly speculation.

Since the Edgeworth-Kuiper Belt is thought to stop around 50 AU or so, this object isn't likely to be a KBO. Inner Oort Cloud seems to fit, though.

Okay, a Moon, Big Deal

[greenhide]

What all of us are wondering:

Is there life on Sedna.

It says that the rock is made out of ice, and ice, as most of you know, is little more than very cold water which has turned into a solid.

Water is the source of all life.

Therefore, there's a very, very good possibility of life on Sedna.

In 2012, I will turn 35, when I will be legally able to run for President of the United States. At that point, I will make it my platform to make a manned mission to Sedna to search for intelligent life.

Since Sedna is so cold, I will recommend that astronaut ice cream *not* be eaten on this trip, and instead my astronauts will be given hot cocoa, tea, coffe, and Lipton's instant chicken noodle soup.

Since Sedna is so far out and is right at the edge of our solar system, I think it might be cool if we put a big billboard that says "Now leaving Solar System. Next star 4.2 light years away. Please do not litter!" And on the other side of the sign, it says, "Welcome to the Solar System! Bad Aliens, please go away." See, that will keep us safe from bad aliens, but encourage the good Aliens to come to engage in tourism, which is ultimately the way we will have to support ourselves in the future, with alien tourism (because all the other work will probably be outsourced to aliens because they will work for cheaper).

Re:9 or 900?

[Phisbut]

I'm for calling everything that orbits the sun a "planetary object"

Then you'd have one heck of a lot of "planetary objects", considering the huge amounts of asteroids that orbit the sun in the asteroid belt between Mars and Jupiter. Should we give a name to all of them? ;-)

I, for one, don't thing Pluto is a planet. It's much too small (at least compared to its moon Charon). They both have a similar mass, which means that Charon does not orbit around Pluto, nor Pluto orbit around Charon. They instead both orbit around a point somewhere between them. Which one is the planet and which one is the moon? They are probably both asteroids (or rocks, why don't we just call them big rocks) orbiting around each other.

And that new Sedna "planet"... it's not even as big as our own moon. Our big white rock has to be called a "moon", but if it had been lucky enough to be further from the sun, it would have been upgraded to "planet"? Size does matter up to a certain point, and Sedna (and probably Pluto too) is too small to be a planet.

Re:It's too far out to be an SKBO

[shadowbearer]

Orbital inclinations which are retrograde are considered to be greater than 90 degrees

SB

Stars are effectively point-sources

[Namarrgon]

I can't block out any of the stars in Orion with a pinhead

Atmospheric (or lens) diffraction, I'd say. If you were out in space, you could probably block it out with the tip of a pin.

More info on this here.