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

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

[kalidasa]

Actually, if you look at the orbits of the KBOs in comparison to Sedna's orbit, even its perihelion is somewhat outside what is theorized to the be outer limit of the Kuiper belt (of the non-scattered KBOs). I looks like there's only one other object, 2000 OO67, that is remotely similar in its distance at aphelion, which is an SKBO; 2003 VB12 is half as far away at aphelion.

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.

9 or 900?

[kippy]

I was in the Pluto-is-a-planet camp for the most part. That's what I was taught in school. The thing is, I think we're going to find more and more that the difference between planet, comet and asteroid is more of a continuum than a stark separation. With that in mind, consider this: I heard this one astronomer on NPR last night say that he had expected to find hundreds of objects around the size of Pluto way out there. This might mean that if we classify Pluto as a planet, we might also have to say that 900 or 9000 other objects are planets too.

The word planet might just be a label that gets increasingly hard to apply as things get smaller just as it seems strange to call Pluto a comet. But just for the sake of not having to find 900 god and goddess names it might make sense to call the first 8 planets "major" and all the Ort cloud bodies "minor planets".

It's all just nomenclature anyway so it's all just a fight of how to right the textbooks.

Re:9 or 900?

[kippy]

even if you had a standard, you'd still run into borderline objects. plus, the standards would be just as arbitrary as the nomenclature we use now.

If you say at least 1000 km diameter, what about a 999km object? What if it's 1001km if measured from a different angle? it's going to be indistinguishable from a 1100km object but it would get a different classification. Same with the atmosphere. Is it required to hold an atmosphere all year long? Why?

I'm for calling everything that orbits the sun a "planetary object" and anything that orbits a planetary object a satellite. That's probably as far as an official classification can realistically go without delving into random requirements.

Calling things just planets would probably just be a rule of thumb thing in which the current 8 or 9 would be grandfathered in.

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:Intermingling of fact and definition

[barawn]

Inner Oort Cloud object

Is this really valid terminology? I've always heard Kuiper Belt, and as the Oort cloud is mainly comets (and is un-freaking-godly huge: 50,000 AU) whereas the Kuiper Belt, where this is, is 30-50 AU.

Last I heard, the Kuiper belt is basically the last rocky objects that formed, and then the Oort cloud is way the hell out there, and it may not even be contiguous (i.e. there might be a gap of 'nothing' between the Kuiper Belt and the Oort cloud). No way to know, of course, as there's no direct observation of the cloud.

Not criticizing, just curious. Astronomers make up new designations every few weeks, so it's a little hard to keep up. :)