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Welcome, Sedna

Continuing with my space-themed weekend, I want to give a warm WorldChanging welcome to Sedna, our solar system's 10th planet. Probably. We'll know more tomorrow, when NASA has a press conference about it.

Discovered last November using Caltech's Palomar telescope on Earth, and just confirmed by the Spitzer Space Telescope, Sedna is a Kuiper Belt Object (KBO) -- one of the ice and rock bodies out past Neptune. Several large KBOs have been discovered over the past few years, but none have been as large as Pluto, also a KBO but also generally considered a planet, too. Sedna appears to be roughly as big as Pluto, or possibly even a bit bigger, and is in a normal orbit. If Pluto's a planet, then Sedna is, too.

Sedna is the Inuit goddess of the ocean -- perfect for the deep black sea of space.

Here is a press release from CalTech with a bunch more information, and here is NASA's information page, which includes the first pictures taken of Sedna:

"Sedna" will become closer and brighter over the next 72 years before it begins its 10,500-year trip to the far reaches of the solar system and back again. "The last time "Sedna" was this close to the Sun, Earth was just coming out of the last ice age; the next time it comes back, the world might again be a completely different place," said Brown.

Makes you wonder what else there is out there in the deepest reatches of the solar system.


Comments (26)

Stefan Jones:

Awww . . .

I was hoping for Yuggoth.



Wow. That's a large body not to have been discovered until now, if it is in a normal orbit. At 10 billion km out, it looks to be about 20% farther from the sun as Pluto at its farthest. Assuming similar albedo to pluto/charon it should be about 16th-18th magnitude, much brighter than other objects resolvable even by earthbound telescopes. Terrestial telescopes can resolve down to about magnitude 25 (10,000 times fainter than Pluto). So if this new object is in the plane of the ecliptic in a normal orbit I'm surprised it hasn't been recognized before.

More details:

(found at: http://www.sanluisobispo.com/mld/sanluisobispo/news/local/8190209.htm )

• Actually discovered on Nov 14, 2003, using the Palomar telescope in California.
• May possibly have a moon -- which appears redder than any object in the solar system except Mars.
• Its year is 10,500 years long, and its elliptical orbit takes it out to as far as 84 billion miles away from the sun.


84 gigamiles? Or kilometers?

Either way, if the previous article is correct and it is currently at 10 Gkm, that is one very elliptical orbit indeed.


Heh. The updated original article has it at both 13 and 17 GKm right now, and the orbital range is stated as Heh. The updated original article has it at both 13 and 17 GKm right now, and the orbital range is stated as

I think that no one has submitted precise real numbers yet, at least to that source.

Sue Carberry:

Does anybody know what time Sedna was discovered? If anyone has this info can you please email me with it. thanks Sue xx sue@wirrarocha.com

Dave Sturm:

Sedna's technically a "scattered disk object", not a KBO. It's not gravitationally in Neptune's zone of influence.

For Sue, "when it was discovered"? Why would that matter? But for what it's worth, look it up at the MPC. It's been listed as 2003 VB12 for some time, and a recent MPEC of 3/15/2004 lists all the observations including the discovery observation to the nearest millisecond.

For those who have no clue... just do a Google on IAU Minor Planet Center. Seek and ye shall find.

de Lauzun:

THat's wonderful.
I would like to know where it is now.
I mean how many degrees in the ecliptic from the equinox position ?
Does anybody know ?



now... hold on a minute... why r u welcoming it NOW?!!! They havn't yet decided if its a planet or not!!!

Christopher Low:

Sedna is NOT a planet.....and neither is Pluto. It is probably the first object to be detected that belongs to the Inner Oort Cloud. It has a very elliptical orbit (like a comet), but it orbits well outside the current known boundaries of the Kuiper Belt.

Capt.Teodor Candrlic:

I would appreciate to hear Mr.Zecharia Sitchin commentary on this regard! Thanks


i always knew there was another planet and i always wished it was named shkimpy or fluckit but sedna sounds kool anough i guess o well one day i will find a planet and i will name it one of those names so ya that is what i no

Well, according to an article in today's paper Sedna is 12.8 billion km away and at it's furthest point is 134 billion km away. It said this is probably the closest it will ever be to Earth, so get a good look now.


Sedna is currently in the constellation Cetus at:

RA: 3h15m10s Dec: +5d38m15s

(Vernal Equinox is, of course, 0h RA 0d Dec, on the 19th at about 11pm here in California)

Not sure why people are interested in the exact time discovered or how close it is to the equinox. It's just over an eigth of the sky away from where the sun will be on the equinox.

Pierre Mottard:

Hi, i,m very excited about the discovery of the new planet Sedna. Also i think, we are going to find a bigger planet in the future, to explain the neptune orbital. I think that, if we consider Pluto as a planet, we have to consider Sedna too, as a planet.
Do someone know if the Hubble telescope is gonna try to get more information about Sedna in the near future?
Thank you.

Russ Ter Beek:

My understanding of what constitutes a planet is that a planet is a body that is large enough to be a sphere due to its own gravitation and that it orbits a star. If it orbits another planet it's a moon. If it's too small to be spherical, it's a planetessimal or planetoid. If it's so large it shines due to internal fusion, even dimly, it's a star. Given these criteria, Sedna would clearly be a planet.


I think cedna and the other large object quaroar should be counted as planets,
the thing about size seems irrelevant as both are not comets, or asteroids, and circle the sun in a huge orbit.
There are dozens of countrys on earth less than 1000km across or even 200km across but we dont call them a non country, or say theyre not part of earth because of there size, so why a different approach to our solar system?, theres probably more small or large planets out there yet to be discovered and still part of our solar system,

just for a bit of fun,these new planets will sure cause a stir for those who follow astrology :), of which i dont

hola me llamo sedna el nuevo planeta ahora conformamos los diez ,bueno mi opinion como planeta es que no es justo que me tomen fotografias porque me duelen mis ojitos


has anyone any idea why the planet is red and shiny? It is like a blushing teenager skulking in the shadows....


It's red because it is actually a giant space battle station sent by the blood god to destroy us. Don't worry though, our organization is dealing with it.


Thank god for the NRA!


u people are weird


Sedna's one of the most fascinating solar system discoveries in the last 10 years. I'm not convinced it's a planet and neither are astronomers, but if we took the definition of being a spherical object orbiting the sun, then we would have to add about a dozen of the largest asteroids as well. I can't wait till they find more. I also can't wait till they find an object that's actually larger than Pluto. Are Pluto and Sedna planets? Stay tuned.


pluto has been recognised as a planet but i think that a 10,500 year orbit is way too much for anyone.

Dear Sirs:
What degree in Taurus is the newly discovered planet Sedna located?


I'm not afraid to state here that I'm a budding astrologer. As such, I'm very excited about Sedna. But why "Sedna?" I always thought the new planet would be named "Vulcan?" Oh, well, we'll just see how everything plays out.
Anywho, there's at least one more planet waiting to be noticed...
I can't wait to hear told all Sedna's properties as they're discovered.
Any astrologers out there conferring on which of the two signs of the zodiac given double-duty wardship by Venus and Mercury this planet rightfully belongs to?


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