Talk:90377 Sedna

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[edit] Misc

I notice that the astronomer Micheal Brown's home page contains a graph showing pollution where he lives in California. He might be interested to know that if he buys a new SAAB, and uses it in Los angeles, it is claimed by Jeremy Clarkson in today's Sunday Times - on the very same day that it announces the discovery of his new 'planet' - that 'the stuff coming out of the back of a Saab turbo's exhaust is actually less harmful than the air that went in at the front. Like a giant vacuum cleaner, in other words'. Anyone know if that's true? Matt Stan 22:13, 14 Mar 2004 (UTC)

That sounds highly implausible. :-) Evercat 22:19, 14 Mar 2004 (UTC)

Drat, looks like someone may have realized that Mike's page on Sedna was getting a lot of hits for something that wasn't supposed to have been announced yet. :) The external link [1] is now giving a 404. Hopefully it will come back online after the press conference, there was a ton of great information there. Bryan 09:04, 15 Mar 2004 (UTC)

Working now MPF 20:51, 15 Mar 2004 (UTC)

[edit] Announcement 15 March

The news briefing is at 2004-03-15t13:00-05:00 http://www.nasa.gov/home/hqnews/2004/mar/HQ_n04040_solar_object.html

I guess I should remove the link to Chad's page, tho it hurts to only have news reports out there when that page (which Mike also had (neither linked to it from their homepages)) has such great info. - Jeandré, 2004-03-15t09:49z

To be pedantic, the Sun would only be blocked this way if your eye's pupil (or camera's aperture) was no larger than the pin head: The sun appears so small from Sedna that it could be completely blocked out with the head of a pin, according to Brown. I guess he means the Sun subtends an angle smaller than that of a pin head held at arm's length. Wikibob 01:50, 2004 Mar 16 (UTC)

[edit] New?

Is this the same as 2004 DW? -- The Anome 13:42, 14 Mar 2004 (UTC)

I don't think so. Still, this hasn't been much reported yet, Google news doesn't turn up much... Evercat 19:07, 14 Mar 2004 (UTC)
I got some information from http://www.theaustralian.news.com.au/common/story_page/0,5744,8968352%255E29098,00.html but don't know how accurate it all is yet. Presumably there will be a flurry of updating on Monday when the press conference is. Bryan 19:17, 14 Mar 2004 (UTC)

[edit] What is it?

Some mention should be made of its highly elliptical orbit... Evercat 01:01, 15 Mar 2004 (UTC)

Or http://www.gps.caltech.edu/~mbrown/sedna/

Sedna is starting to sound a lot like a scattered disk object to me. Bryan 01:04, 15 Mar 2004 (UTC)

The news item actually said that NASA is going to make its announcement tomorrow. Matt Stan 01:11, 15 Mar 2004 (UTC)

Can I suggest (astronomical object) instead of (object)? - the latter is a bit.. amibguous. Ed g2s 02:01, 15 Mar 2004 (UTC)

Or Sedna (planetoid)? Evercat 02:16, 15 Mar 2004 (UTC)
I'd suggest Sedna (plutino).—Eloquence
On second thought, this may be inaccurate given the definition provided at plutino.—Eloquence 04:51, Mar 15, 2004 (UTC)
Yes the Jewitt article cited there requires a very specific orbital diameter to be called a plutino. Joelwest 13:39, 20 Mar 2004 (UTC)

re previous attempts to define "planet" : "[Michael] A'Hearn and others say it's reasonably likely that another object as big or larger than Pluto will be found orbiting the Sun even farther out. What happens then? Start the fight over again."[2]

One definition of a planet is "any body in the solar system that is more massive than the total mass of all of the other bodies in a similar orbit.". Another "made round by its own gravity". Also, "anything as big or bigger than Pluto." - Jeandré, 2004-03-18t09:04z --- Dan Green's page [3] says that the whole "planet" vs. "not a planet" debate is a myth of the popular press that is long discredited in astronomy. The real question is classifying major planet vs. minor planet, and a case can be made that Pluto and Sedna are both minor planets. Joelwest 13:39, 20 Mar 2004 (UTC)

[edit] Planetoid?

FYI some people seem to be calling Pluto also a planetoid. -- Paddu 14:56, 17 Mar 2004 (UTC)
Had Pluto been discovered today, it would most likely not be called a planet. According to the IAU, it is one, though. [4]
That may very well be the case - but the point is - Pluto's classifaction is the subject of debate. It is not agreed whether it is a Planet/Planetoid etc. The point of the words in brackets is for disambiguation, not definition (that can be discussed in the article). Sedna (AO) distinguishes it well enough from any other Sedna without making a decision about its classification. Ed g2s 18:49, 17 Mar 2004 (UTC)

[edit] 12 or 16?

Note discrepancy over official name. Brown's web site says 2003 VB12, but the http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/quickfacts.shtml , bbc, etc say VB16. NealMcB 01:42, 2004 Mar 16 (UTC)

This BBC News article [5] also says VB12. Except for your link I can find no other site which calls it VB16 (where at the BBC?). — Jor (Darkelf) 01:52, 16 Mar 2004 (UTC)
This link [6] said VB16 when it was indexed by Google, but now says VB12. VB16 was probably an error. — Jor (Darkelf) 01:56, 16 Mar 2004 (UTC)

[edit] Call for votes: What shall the name of this article be?

[edit] Voting

Vote for the article name you support most by typing the following beneath it: #~~~~

Poll closes 04:00, March 21, 2004 (UTC)

2003 VB12 (2)

  1. Sedna
  2. Anthony DiPierro

Sedna (astronomical object) (7)

  1. Bryan 05:36, 16 Mar 2004 (UTC)
  2. Minesweeper 10:19, Mar 16, 2004 (UTC)
  3. MPF 14:18, 16 Mar 2004 (UTC) This covers all eventualities
  4. Anthony DiPierro 15:28, 16 Mar 2004 (UTC) Planetoid sounds stupid. Anthony DiPierro 15:28, 16 Mar 2004 (UTC)
  5. Ed g2s 18:01, 16 Mar 2004 (UTC) Planetoids aren't very well defined. The article says they are more like asteroids and are "much smaller than planets". Sedna is similar in size to Pluto. From what I've read, not even the experts in the field can decide on what each definition means - and therefore what Sedna is. Until they (or Wikipedia:WikiProject Astronomical Objects) can come up with some definitions, AO is the only sensible suggestion. Anything with planetoid in it must be ruled out.Talk:Sedna_(astronomical_object)#Planetoid?
  6. ChrisO 14:51, 17 Mar 2004 (UTC) Support, for the reasons given above by Ed g2s.
  7. Michael Warren 15:38, Mar 17, 2004 (UTC).

Sedna (planetoid) (15)

  1. RickK | Talk 03:59, 16 Mar 2004 (UTC)
  2. Davodd 03:58, Mar 16, 2004 (UTC)
  3. Bryan 05:36, 16 Mar 2004 (UTC) Either this or (astronomical object) is quite sufficiently vague, IMO, and fits with our disambiguation standards. But whatever gets chosen, can we please stop moving the article around every few hours? :)
  4. Seth Ilys 06:11, 16 Mar 2004 (UTC). A uniform article naming system for astronomical objects needs to be established, preferably through Wikipedia:WikiProject Astronomical Objects.
  5. Jeandré, 2004-03-16t10:04z.
  6. Minesweeper 10:19, Mar 16, 2004 (UTC)
  7. — Jor (Darkelf) 11:42, 16 Mar 2004 (UTC) Best of the available options for now. Once more Oort objects are discovered move to Sedna, Oort Cloud object (with final name replacing Sedna).
  8. andy 14:54, 16 Mar 2004 (UTC) (until IAU comes up with a naming scheme for such an object, or gives it the final name)
  9. Timwi 15:22, 16 Mar 2004 (UTC) (good idea, better than astronomical object)
  10. Dmn 22:20, 16 Mar 2004 (UTC) Planetoid is an excellent word to use
  11. Paddu 14:56, 17 Mar 2004 (UTC)
  12. Rmhermen 16:27, Mar 17, 2004 (UTC)
  13. Michael Snow 18:13, 17 Mar 2004 (UTC)
  14. Texture 18:19, 17 Mar 2004 (UTC)
  15. Joelwest 13:32, 20 Mar 2004 (UTC) after all, that's what its discoverers use
  16. Ryan_Cable 12:11, 25 Mar 2004 (UTC)
  17. WilliamKF 22:25, 18 September 2006 (UTC)

Sedna (astronomy) (1)

  1. Merovingian ↕ Talk 10:30, Mar 17, 2004 (UTC) - I don't know about you, but I like simplicity.

[edit] Debate

You may want to reconsider this. As of today, there is no sufficient data to classify this object. Although its more appropiate name would be Sedna, Planetoid 2003 VB12. As far as we know, it may be named as Sedna, Inner Oort Cloud object 2003 VB12, Sedna, Oort Cloud object 2003 VB12 or even Sedna, Trans-Neptunian object 2003 VB12. Obviously, Sedna is a planetoid and a Trans-Neptunian object, but it may or it may not be an Oort Cloud object or an Inner Oort Cloud object. --Maio 05:24, Mar 16, 2004 (UTC)

If it's obviously a planetoid, then what's wrong with calling it (planetoid) for now since there aren't any other significant planetoids named Sedna for it to be confused with? We can move the article one last time once its classification becomes better defined, if necessary. Bryan 05:38, 16 Mar 2004 (UTC)
The problem is that the object could be classified as two things at the same time, a planetoid and a TNO. But since it has been called more as a planetoid, I beleive that it is more appropiate to rename it to Sedna, Planetoid 2003 VB12 to make it detailed, precise, and human-readable at the same time. —Michael | Talk 14:23, Mar 16, 2004 (UTC)
Must the 2003 VB12 be in the name? Not only is a numeric string like that imnsho very ugly, but the object is also very unlikely to be ever called both Sedna and 2003 VB12 at the same time. Sedna (planetoid) with a redirect from 2003 VB12 would seem best of both worlds. — Jor (Darkelf) 14:34, 16 Mar 2004 (UTC)
Copy/paste from the same article: By the IAU naming conventions for asteroids, the official name is 2003 VB12, until its orbit can be established well enough. Only then do the discoverers have the right to suggest a name. So, IMHO, at the moment it should include it. Perhaps later, when the name is officially settled down, it could be moved to Planetoid Sedna. —Michael | Talk 14:45, Mar 16, 2004 (UTC)
But by then it will have a asteroid number (at least if the IAU considers it an asteroid as well), and then by the naming standard for asteroids it'd have a name like 90000 Sedna. But till then Sedna (planetoid) should be the best and shortest alternative. andy 14:54, 16 Mar 2004 (UTC)
I think they know enough to call it a planetoid since the size is much bigger than a meteorite and about half the size of the smallest major planet, Pluto. Being both a planetoid and TNO is not a problem: most of the planetoids outside the Asteroid belt are TNO's. And if you don't classify comets as TNO's, all the TNO's we can see so far are planetoids. Joelwest 16:26, 20 Mar 2004 (UTC)

[edit] Other Suggestions

How about moving this to Sedna and moving the goddess page to Sedna (goddess) or whatever? That's basically the situation with Quaoar... Evercat 12:37, 16 Mar 2004 (UTC)

Not sure if that is proper, as Sedna is not yet its name. — Jor (Darkelf) 14:34, 16 Mar 2004 (UTC)

[edit] Farthest from the sun?

"...is farther from the Sun than any previously known object in the solar system."

Not for several months, now. Voyager 1 is now 91.4 AU from the sun, and Sedna is more like 90.3 AU according to Brown's paper. The article wording was "Its discovery was the furthest distance at which any object in the solar system has ever been observed" (which still needs rewording...). So as for the time of discovery and the geocentric viewpoint, the ephemeris shows Sedna at 88.63 AU from earth when discovered (right at opposition) on Nov 14. Voyager 1 was on the far side of the sun from us then so despite moving at 3.625 AU/year, it was further from earth than Sedna then also. So I added the word "natural" to the article. I'm not sure which was further from the sun at the time of discovery - probably Sedna. NealMcB 18:30, 2004 Mar 23 (UTC)

So the current sentence remains correct. "natural" object -not any object and "furthest observed", not furthest object. (Of course, we can't observe Voyager 1) Rmhermen 18:41, Mar 23, 2004 (UTC)
I agree the sentence is correct given the addition of "natural". But Voyager 1 certainly can be observed, at radio wavelengths. It may have recently discovered the heliopause, and we expect to talk to it for another 2 decades when it is, I guess, 150 AU away! NealMcB 16:40, 2004 Mar 24 (UTC)

Hmm, what about comets like Hale-Bopp, for instance? Is that not considered part of the solar system? Is it because of the plane? What about other Oort cloud objects which have a more even plane? Anthony DiPierro 14:04, 16 Mar 2004 (UTC)

It is my understanding that this is the only known Oort cloud object but I can't explain about the comets. Probably it is the furthest distance anything has been detected at, comet being too small to see at that distance with current technology. Rmhermen 15:01, Mar 16, 2004 (UTC)
Hale-Bopp has an aphelion of 372 AU but it will take over 1000 years from now to get there (Sedna's is 850 AU). Maybe no known comet is currently past 90 AU? Rmhermen 15:21, Mar 16, 2004 (UTC)
Probably both farthest detected object, and currently farthest known? Should we note that in the article and hope that someone who's sure fixes it for us? Comet Halley holds the record distance for a comet observation: 28 AU. Comet Hale-Bopp has an aphelion of 457.583 AU. "aphelion, Comet Hyakutake will be about 800 AU's". "The aphelion (most distant point from the Sun) of a long-period comet may be more than 50,000 astronomical units away." - Jeandré, 2004-03-16t15:42z
Hmm, OK. I thought Hale-Bopp got farther than that. All that talk about the Oort cloud being 50,000 to 100,000 AU away and everything. Anthony DiPierro 15:45, 16 Mar 2004 (UTC)
You must have missed the creation of the "new" and much closer Inner Oort cloud yesterday! I would say Sedna has the furthest detection claim for any object and the furthest perihelion. I am not sure that it is the current furthest known object. It is not clear whether Mike Brown's map of solar system objects' positions includes comets. Rmhermen 15:52, Mar 16, 2004 (UTC)
Actually, that's what confused me. If Sedna is only part of the "inner" Oort cloud, how could it be the furthest known object. Either the "outer" Oort cloud is not known, or it's not part of the solar system (apparently it's the former). Anthony DiPierro 16:02, 16 Mar 2004 (UTC)
Yup, no outer Oort cloud objects have been discovered yet. The Oort cloud had only been predicted in theory until Sedna came along and although it looks like the theory may need tweaking, it's still pretty generally accepted. Bryan 17:48, 16 Mar 2004 (UTC)
Acording to Heavens above, C/1999 LINEAR S4 is currently more than 10 AU from the sun, but has an aphelion of 1 892.19 AU. So while Sedna is the farthest detected TNO, and may currently be the farthest of all known TNOs, LINEAR-S4 will eventually be farther than Sedna. I'm sure there are other comets with even greater aphelions, tho none of them may currently be beyond 90 AU. If a comet was calculated to have most of its orbit outside the Edgeworth-Kuiper belt, then Öpik-Oort cloud (which includes both inner (disk roughly on the ecliptic) and outer (the spherical cloud)) objects have been discovered before Sedna, no?. - Jeandré, 2004-03-17t11:09z
Marc W. Buie from Lowell Obs has 2000 OO67 with an aphelion of >1000 AU. Is this the first discovery of a non-comet inner OOCO? - Jeandré, 2004-03-19t09:56z
That objects perihelion is at 20 AU while Sedna is at about 76 AU. I doubt they would be considered in the same class, however stay tuned the definition are still changing. Rmhermen 14:50, Mar 19, 2004 (UTC)

I thought when they said "farthest from the sun," they were refering to average distance, or semi-major axis. However, Sedna's range from 76 to 900 AU [7] will give it a closer average distance than C/1999 LINEAR S4. Another way to check which has farthest average distance is to look at their periods (Kepler's third law P^2\sim a^3); whichever has the longer orbital period is further away on average.
Regarding Oort cloud objects, I thought the comets were all part of it? --zandperl 17:05, 17 Mar 2004 (UTC)

They are theorised to be, but I don't believe any have ever actually been observed 'out there', only in-system. -- Michael Warren 17:09, Mar 17, 2004 (UTC)

Some comets are thought to originate in the Kuiper Belt. Others, with a higher inclination and longer periods, are thought to originate in the Oort cloud. Some, like Halley's comet, which has a high inclination and a short period, could really have originated from either, but was thrown off its original path by later interactions. According to WP, it's came from the Kuiper Belt. Presumably we have observed comets from farther away, but it's hard to give conclusive evidence when the periods are so long. Anthony DiPierro 17:14, 17 Mar 2004 (UTC)

The idea is that the Kuiper Belt is in line with the plane of the planets, but the Oort cloud is a sphere. But now, according to the new theories (not sure how new), there is an inner oort cloud which extends in a plane to the actual Oort cloud. This part I'm still not sure of exactly what the theory is. I never learned it in my astronomy classes a few years ago. Anthony DiPierro 17:20, 17 Mar 2004 (UTC)

I never learned it in my astronomy classes a few weeks ago, so I wouldn't think the professionals are quite sure just yet... :) -- Michael Warren 17:30, Mar 17, 2004 (UTC)

The article says "Its discovery was the farthest distance at which any natural object in the solar system has ever been observed. ... At its discovery, it was about 90 AU from the Sun, approaching perihelion." Is this still true? I believe 2003 UB313 was 96.928 AU when it was discovered on January 8, 2005. See http://neo.jpl.nasa.gov/orbits/2003ub313.html - Mark Mathu July 30, 2005

No it's not, thus the update notice. I haven't bothered to rewrite; perhaps something along the lines of 'was the farthest when discovered' would be appropriate. kwami 06:19, 2005 July 31 (UTC)

[edit] Use of Images

[edit] Reason to restore photographic image

I feel like with all of the artist's renderings (which may or may not be accurate), we should include at least one *real* picture of the object, and so I've restored the photographic image with Sedna as the tiny dot. It's the most meaningful of all the images present to *me*, and I think it will be to other people as well... - Seth Ilys 03:32, 16 Mar 2004 (UTC)

I don't care if the picture is on the article or not, as long as the other 3 are in it. The reason why I removed it is because, to the general public, that image is just a bunch of dots with no particular meaning. Basically, it is something that any artist can produce with Photoshop by using light effects. (regardless if it is an official image) --Maio 03:56, Mar 16, 2004 (UTC)

"...may or may not be accurate" - what nonsense. The painting DOES NOT BELONG: it is pure speculation and wouldn't even qualify as a "best guess". Usually, our speculations fail to encompass the spectacular diversity of our universe.[anon]

[edit] In-progress infobox

Image:Ssc2004-05b medium.jpg
Artist's concept of Sedna by R. Hurt of NASA / JPL-Caltech.
Orbital characteristics
Orbit type Inner Oort cloud
Semimajor axis 480±40 AU
Eccentricity 0.84±0.01
Orbital period ~10,500 years
Inclination 11.927°
Perihelion distance 76±4 AU
Next perihelion 2075-09-22±260d
Distance from sun at discovery ~90 AU
Physical characteristics
Diameter < 1800km
Mass unknown
Density unknown
Rotation period ~960h
Albedo unknown
History
Discoverers C. Trujillo, M. Brown, D. Rabinowitz
Discovery date November 14, 2003

I moved the image outside of the table so that it can be used as a thumbnail and therefore provide an intuitive link to a larger version. —Michael | Talk 14:40, Mar 16, 2004 (UTC)

I would personally prefer the discovery image (the 2003-11-14t06:32z photo rather than the one with the circle, since the circle seems to have 2 objects in its centre) above the table until Hubble can give us something more substantial. What arguments are there for the use of the artistic impression at the most prominent position on the page? - Jeandré, 2004-03-17t10:30z

[edit] Pics included - query

Are the various artists impressions and photos included here and under Quaoar, etc., not copyright? Has permission for their use on a free access site (from where they can, and will, be lifted by other parties and used without acknowledgement) been granted? - MPF 14:18, 16 Mar 2004 (UTC)

NASA images are public domain. But JPL-Caltech images aren't necessarily. Was this image made by NASA or JPL-Caltech? Anthony DiPierro 14:42, 16 Mar 2004 (UTC)
Refer to [8] about the images presented in this article. NASA can't restrict access to the general public, but they can for commercial purposes. —Michael | Talk 14:50, Mar 16, 2004 (UTC)
That link doesn't work. Anthony DiPierro 14:51, 16 Mar 2004 (UTC)
Works for me right now. It was down a few hours ago. —Michael | Talk 15:30, Mar 16, 2004 (UTC)
OK, it's up. I'll look into it. Asking around on IRC, someone said that while images created with US taxpayer money are public domain, the US government can have copyright transferred to it. But I can't find any direct citations which back any of this up. Anthony DiPierro 15:51, 16 Mar 2004 (UTC)
Well, it's quite belated, but here it is: "A 'work of the United States Government' is a work prepared by an officer or employee of the United States Government as part of that person's official duties." "Copyright protection under this title is not available for any work of the United States Government, but the United States Government is not precluded from receiving and holding copyrights transferred to it by assignment, bequest, or otherwise." - Title 17, chapter 1, 101 and 105. anthony (see warning) 01:59, 7 Apr 2004 (UTC)

[edit] Possible moon

This article (BBC) says Sedna might have a moon. WooHoo. --Phil | Talk 16:47, Mar 17, 2004 (UTC)

See Sedna (astronomical object)#Characteristics - it's already in the article. andy 19:55, 17 Mar 2004 (UTC)

[edit] Red planetoid in Oort cloud

I don't see any reference to the red color of the planetoid in this article. I'd add that in myself but I couldn't find a good place for it. Has it been confirmed that Sedna is in the Oort cloud? That seemed to still be in disputed.

- Texture 18:21, 17 Mar 2004 (UTC)

Quote from M. Browns webpage: From observations at the 1.3-m SMARTS telescope in Chile, we do know that Sedna is one of the most red objects in the solar system -- almost as red as Mars. andy 19:57, 17 Mar 2004 (UTC)

It's not even confirmed that there is an Oort cloud. The whole thing is currently just theory. Anthony DiPierro 19:50, 17 Mar 2004 (UTC)

[edit] Article Naming

Should this be moved to 2003 VB16 now, as that's the official name? Sarge Baldy 13:09, Mar 19, 2004 (UTC)

No, official name is 2003 VB 12 - see the discussion above why 16 is wrong. But as the name Sedna has been so much promoted by the media moving it to that name would create more confusion. See also the article naming poll above. andy 13:14, 19 Mar 2004 (UTC)

http://news.bbc.co.uk/2/hi/uk_news/magazine/3515658.stm

[edit] copy & paste move?

Why has this article been moved by copy&paste rather than moving? User:Sedna is not the only contributor to this article. — Jor (Talk) 15:54, 20 Mar 2004 (UTC)

Furthermore, the poll is still ongoing. If it is decided the article must be moved it should be done by a sysop who can keep edit history, not by some over-eager editor destroying edit history. — Jor (Talk) 16:02, 20 Mar 2004 (UTC)

[edit] Jupiter

I removed this from page: Studying theories of the Solar System early formation mechanisms indicates that many objects would have been ejected by Jupiter and the other giant planets very early after the formation of planets, during the early bombardment phase of Earth's history. Sedna is possibly our best candidate for a detection of one of these well travelled objects, as it is in an orbit not easily explained without perturbation; Models produce nearly circular orbits, highly eccentric orbits (and Sedna's orbit is of cometary eccentricity) have to be produced by perturbation or partial ejection.

If you read the original discovery paper (available through the Mike Brown's page link in article, you find that this theory was rejected as the orbit is far too large to have been caused by Jupiter. Of course it may still be open to other interpretations. Perturbation is still the key but they are talking globular cluster interactions. Rmhermen 13:55, Mar 21, 2004 (UTC)

[edit] Moving per vote to Sedna (planetoid)

Per the vote, I am moving this article to Sedna (planetoid) - Texture 16:56, 25 Mar 2004 (UTC)

[edit] Trimmed references

Per the suggestion from Jeandre', I removed some of the references to the less technical news articles. If people find this excessively deletionist, feel free to revert --- I won't be offended. --- hike395 22:20, 7 Apr 2004 (UTC)

[edit] True or false??

True or false?? Sedna is the tenth planet from the sun. 66.245.104.154 02:18, 10 Apr 2004 (UTC)

True, but only for certain definitions of planet. - Fennec 02:25, 10 Apr 2004 (UTC)
False, for other definitions of planet. :) Bryan 04:22, 10 Apr 2004 (UTC)
Almost certainly false for any definition. Rmhermen 12:31, Apr 10, 2004 (UTC)
Absolutely False! J P 21:54, 16 January 2006 (UTC)
My opinion...I think it should be a planet...
False. By any and every conceivable definition. Pluto/Charon and the large plutinos, as well as Quaoar, and Eris are all in line in front of it anyhow. Sedna is much more comet-like at least orbitally. Even 1 Ceres has a better reputation, so let's put this to rest now. 69.136.238.165 02:55, 14 September 2006 (UTC)

[edit] Pinhead comment

This parenthetical was just added by an anonymous user:

According to Brown, the Sun appears so small from Sedna that it could be completely blocked out with the head of a pin held an arm-length away (while it's certainly true that the sun's apparent size as seen from Sedna is smaller than the apparent size of the pin hed at arm-length, a human would still see the sun because both the human pupil and the sun are larger than a pin head).

Uh, what? The Sun's actual size is irrelevant, Brown was merely talking about its apparent size. The size of the pupil is indeed relevant, but it merely puts additional constraints on how small the Sun would have to appear to be blocked out by a pin head, it doesn't make it impossible as far as I can tell. But since I haven't done the math on this, I'm hesitant to just revert - it could well be that Brown is wrong and this parenthetical is just poorly worded. Anyone have input, or a source on Brown's comment? Bryan 00:51, 14 May 2004 (UTC)

The Sun's size is relevant, but not sufficient to determine whether it's blocked out. If we consider the Sun's distance to be infinity compared to the pinhead's distance, then as long as the pinhead is smaller than your pupil, the Sun will always be visible, even if it is tiny. It's difficult to word the conditions without drawing pictures though. If your pupil is infinitessimally tiny, then Brown's comment is correct, otherwise your pupil's diameter, the pinhead's diameter and distance, the Sun's diameter and its distance are all relevant. What one would see (with a proper solar filter to save your sight) is either a blurred image of the pinhead with the Sun in focus around it, or a blurred image of the Sun with the pinhead blurred inside it. Maybe a better, but not 100% comprehensive, rephrase could be "... a human would still see the sun because the human pupil is larger than a normal pin head." -Wikibob | Talk 10:29, 2004 May 14 (UTC)
The solution is to sidestep the issue by simply noting that the Sun looks smaller than the pinhead, without mentioning blocking. -- Curps 14:04, 14 May 2004 (UTC)
I removed the sentence completely; we don't need some arbitrary comparisons in some arbitrary asteroid articles just because the discoverer made some comment (which was wrong! - at least in the way it was quoted) in an interview. 193.171.121.30 00:54, 6 Dec 2004 (UTC)

[edit] Sedna's naming

Sedna has indeed officially received its name in the latest batch of new names (MPEC 2004-S75) despite some controversy on the announcement proceedings. Asteroid lists on the Minor Planet Center site weren't updated. Jyril 15:45, 28 Sep 2004 (UTC)

[edit] Inconsistencies and inaccuracies in this article

The orbital period is given as 4108714.108 d which equals 11249.28639.. years while elsewhere it states 11487 years. Figures should not be given with vast numbers of digits precision when they are so uncertain, and consistent figures should be used. The diameter is given as 1180-1800 km and then translated as 730-1470 miles. In fact 1800 km = 1120 miles so something is badly wrong. Under orbital characterists the distance is given as 76.1 to 942 AU (elliptical) and elsewhere in the table as 76.032 to 928.048 AU. Again, consistency would help with precision kept to a realistic value. User:RayTomes 7 May 2005.

[edit] Sedna good target for mission

If Sedna spends a great deal of time beyond the heliopause, would it not record brushes with supernova within some hundreds of LY, and keep a record if such effects in a kind of geological layering of cosmic rays and radiation impacts like the earth bound ice sheets record information on dust, temperature and such. Perhaps a more interesting place to go than Pluto which may have been remade with a significant impact to create Charon as I've seen suggested?

You've made a good point, and perhaps in a few years the article can add information about a speculative mission to Sedna. The extreme redness of Sedna could indicate some very unusual things, too countless to speculate, but some include ejection from the inner solar system; ejection from a different system into ours, etc. But more likely than not, there's something still more massive than Enlil (2003 UB313) lurking around that is responsible for Sedna having been scattered to this unusual orbit. In any event, getting out there and landing something on Sedna in a future generation could be very informative. --Sturmde 01:07, 22 August 2005 (UTC)

Enlil? I found no match for this name. 2003 UB313 is now officially known as 136199 Eris; is that what you meant? At any rate, even detailed spectroscopy of Sedna's surface could yield some insights. Small and distant target for a landing mission though, most likely a flyby. 69.136.238.165 02:55, 14 September 2006 (UTC)

[edit] damocloid asteroid?

Should 90377 Sedna be classified as a "damocloid asteroid"? --Hello World! 04:30, 2 August 2005 (UTC)

No, damocloids visit the inner Solar System, and have orbits typical to long-period comets. It very likely that they are dormant comets that have lost most of their volatile material and because of that appear asteroid-like.--Jyril 08:39, August 2, 2005 (UTC)

[edit] 11th planet?

no.

See above, not even close. 69.136.238.165 02:55, 14 September 2006 (UTC)

[edit] Moon? Planet a not?

People say that Sedna is not considered a planet just because it does not have a moon... I think because of this, Brown say that Pluto should not be a planet...

However the truth is...all planets with solid surface has no moon (except for our Earth)

Mercury, Venus -> no moon...

Earth -> don't know where the moon came from...

Mars -> captured asteroid objects

Pluto -> captured kuiper object —The preceding unsigned comment was added by Ragnaroknike (talk • contribs) 09:39, 20 July 2006 (UTC)

Earth's moon's creation theory: Giant_impact_hypothesis. Sedna's and other's status as planets will be decided when IAU defines it in September, although I don't think anyone thinks Sedna is a planet (more of a large comet IMO). Also, please remember to sign your comments. DanPMK 10:24, 23 July 2006 (UTC)

I'm not clear why Sedna is considered less certain to qualify as a pluton than Xena. Is it because we don't know how round it is? HenryFlower 21:03, 18 August 2006 (UTC)

Well, it's not a plutino or a KBO since it's so far out. Eris (2003 UB313 "Xena") is in a resonance with Neptune (17:5) but Sedna is so distant it is unlikely to be even influenced by planetary orbits. So classing it with Pluto-prototypes would not be proper. 69.136.238.165 02:55, 14 September 2006 (UTC)

[edit] Is it now a candidate PLANET (not just a dwarf planet)?

The definition now adopted says that something is a planet if it has cleared the neighbourhood around its orbit. Sedna looks to be outside the Kupier Belt even at its closest approach. A few small object would not count - Jupiter has its 'Trojans' etc.

Of course Sedna is suspected of being the first of a large class of such objects. But if their orbits did not overlap, that would still count.

(Of course no one has yet proved that it is spheroid, though it seems too big to be anything else.) --GwydionM 18:48, 24 August 2006 (UTC)

Thank you for noticing this. You seem to be the only person except me who's done so. Its orbit is indeed cleared, and it's almost certainly round, and this makes it a planet by the new definition.
I'm sure the people who created that definition didn't *want* Sedna to be a planet, though, and won't bother considering it as one. Perhaps they'll say something like 'Sedna doesn't count because although Sedna's orbit is cleared, Sedna didn't do the clearing'.
Unfortunately putting this in the article is OR. Ken Arromdee 14:49, 26 August 2006 (UTC)
Yes, that would obviously be original research, and very substantial research at that. There is simply not enough information yet about whether other Sedna-type objects exist on similar orbital paths yet. It will take some time to discover anything else that might be out in that range. When writing articles on celestial bodies with 10,000+ year orbits, patience is called for. Regarding "Sedna looks to be outside the Kupier Belt even at its closest approach": that is a matter of some dispute in the scientific community; we don't really know the extent of the Kuiper Belt or the Oort Cloud yet. Regarding "Its orbit is indeed cleared", there is simply no evidence one way or the other about that.Derek Balsam 15:00, 26 August 2006 (UTC)
It would be exceedingly unlikely that Sedna is only such body. What comes to its Oort cloud membership, it probably is far too close to Sun even at aphelion. I'm quite convinced that it represents a yet-to-be-found population of intermediate objects between the Kuiper belt and the Oort cloud.--JyriL talk 15:11, 26 August 2006 (UTC)

.

[edit] Refs

Some of the "external sites" are the actual references to be quoted in the article; some are now obsolete news to be removed. Cleanup required, I believe. Current refs (scientific papers) were missing; I added a few but the article need to be refreshed IMHO. Eurocommuter 13:17, 16 September 2006 (UTC)

The objective of [citation needed] is precisely that, find a new ref. For example the paper it comes from, not necessarily the old article from Planetary Society. Eurocommuter 14:14, 16 September 2006 (UTC)

I didn't look, but I'm assuming the statement supported by the old news article? If so, it's a fair temporary ref until a better ref is found. {{fact}} is for statements that have no reference at all. Also, when the Planetary Society 404 ref was deleted, a sentence of content and a second (live, not 404) ref to NewScientist were also deleted. The fact tag was then added to the phrase that the NewScientist ref had supported. Gimmetrow 15:01, 16 September 2006 (UTC)

My apologies; indeed, unintentionally I deleted more than I wanted. My intention was to find and replace 404 with the original scientific paper(s) for the same statement. Regards Eurocommuter 15:19, 16 September 2006 (UTC)

[edit] Replace image with HST image

I think a better more representative image of Sedna would be the cropped HST image1 in the article2. Should someone replace Image:Sedna-NASA.JPG? -- Kheider 18:44, 1 November 2006 (UTC)

[edit] Albedo

If 90377 Sedna has a much redder color index plot (1.24,0.78) than 20000 Varuna (0.93,0.64), and Varuna has an albedo of 0.04, why does Sedna have its albedo listed as ">0.2?"? -- Kheider 08:32, 8 November 2006 (UTC)

Because there has been no detection of Sedna in the thermal IR. That sets an upper bound on its size and a lower bound on the albedo. Color doesn't enter into it: a redder surface doesn't necessarily have a lower broad-band albedo. In an extreme case, my red shirt has an albedo of say ~0.4 and is redder than either Sedna or Varuna. Michaelbusch 18:05, 8 November 2006 (UTC)

[edit] History of Sedna's Orbital Period

10,500 01:37, 15 March 2004
11,487 00:17, 6 April 2004 64.228.80.85
11,249 23:51, 27 January 2005 Urhixidur
12,050 00:43, 17 January 2006 24.201.139.114
12,059 12:40, 13 August 2007 JamesFox Lowell DES

Which is considered better Lowell DES or Horizons? DES gives the current 12,059 and Horizons shows 10666.77±119.3. -- Kheider (talk) 04:39, 19 November 2007 (UTC)

[edit] Planet

At best Sedna is likely less than 42% the mass of Eris. Sedna could have a radius of only 590km with a density similiar to Tethys (moon) at 0.97 g/cm^3. This would yield a mass of only 8.3×1020 kg. The IAU will not give planetary status to any small object with a poorly known diameter. Either way, it is not massive enough to be have cleared its orbit of other objects comparable in size to itself. -- Kheider (talk) 21:38, 16 February 2008 (UTC)

I've added a note about Sedna's Stern-Levison parameter (which described how gravitationally dominant it is in its orbit). (I don't believe that this classifies as Original Research, since it is simply plugging some numbers into an equation.) Bluap (talk) 23:11, 16 February 2008 (UTC)

[edit] Sedna claimed to reach Perehelion by 2075. Please don't delete this

I notice that the source for this is source 5 but it doesn't say anywhere that it will reach Perihelion in 2075. It does say that Sedna will beat Eris in 2114 as the farthest object from the sun but the Perhelion date of 2075-2076 is not listed in source 5, which is the source it is supposed to come from. -Thank You.Maldek (talk) 07:19, 16 May 2008 (UTC)

Hello Maldek. I am the person that actually put that content in the article.

  • Ref 1 from the Lowell DES website shows, "Time of Perihelion: 2479283.2278". (Ref 6 shows how to convert the number to 2075-12-11.)
  • Ref 5 is generated by JPL's Horizon program and shows a perihelion date of 2076-Jul-13. The reason the programs come up with slightly different dates is because they use slightly different numbers to do the calculations. Keep in mind that Sedna is very far away and has only moved a little bit over the 17 years (see precovery) that they have photos of it. They still do not know the orbit well enough to know if it takes 10 thousand or 12 thousand years to go around the Sun.

I just re-ran the numbers with Horizons (using Soln.date: 2007-Nov-26 / 64 obs / last obs: 2007-11-08) and it now comes up with a perihelion date of 2076-Jul-18 instead of the older value (from 2007-11-19) of 2076-Jul-13. But that is still only a rough estimate until the orbit is better determined. I cite both years because they come from two different sources. -- Kheider (talk) 08:13, 16 May 2008 (UTC)

[edit] Missing context.

This sentence seems doesn't seem to follow on from the previous sentence an makes little sense as it exists: "A number of explanations have been put forward since, including a passing star and a distant, planet-sized object."

Can someone fix it? Duggy 1138 (talk) 03:18, 7 June 2008 (UTC)