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Toutatis
2004-Mar-16, 05:39 AM
A seemingly overlooked/under-discussed characteristic Re: Sedna (on these fora) is the enormous eccentricity of said body's orbit --- Actually it is now near perihelion (70-odd AUs) aphelion approaches 1,000 AUs!!!

For a qualitative 'take' on this, please have a look at the applet (linked below) Ron Baalke kindly 'kluged' JPL's orbit viewer such that users might view Sedna's Entire orbit :-)

http://neo.jpl.nasa.gov/cgi-bin/db_shm?des=2003+VB12&view=Far

Please note: ‘2003 VB12’ is the official designation for ‘Sedna’ (a provisional name)

Very best regards
Dan Sarandon

milli360
2004-Mar-16, 11:55 AM
For a qualitative 'take' on this, please have a look at the applet (linked below) Ron Baalke kindly 'kluged' JPL's orbit viewer such that users might view Sedna's Entire orbit
LOL! I cranked away at that for years, and they hardly moved. :)

If perihelion is 75 AU, and aphelion is 800 AU, then the semimajor axis is 437 AU, right? That makes the semiminor axis 245 AU, if my math works out. We finally have an object whose orbit actually looks like an ellipse!

Archer17
2004-Mar-16, 03:33 PM
Cool link Toutatis!

JohnOwens
2004-Mar-16, 07:15 PM
If perihelion is 75 AU, and aphelion is 800 AU, then the semimajor axis is 437 AU, right? That makes the semiminor axis 245 AU, if my math works out. We finally have an object whose orbit actually looks like an ellipse!

What, you've never heard of "comets"? :wink:

tofu
2004-Mar-16, 07:27 PM
We finally have an object whose orbit actually looks like an ellipse!

uh, all orbits are ellipses.

daver
2004-Mar-16, 07:33 PM
We finally have an object whose orbit actually looks like an ellipse!

uh, all orbits are ellipses.
Yeah, but most of them, if plotted, look like circles, possibly slightly offset from the origin.

JohnOwens
2004-Mar-16, 07:37 PM
We finally have an object whose orbit actually looks like an ellipse!

uh, all orbits are ellipses.

Oh, come on, even I was willing to let that one slide. After all, he said "looks like an ellipse" (emphasis added), which is rather different than being an ellipse. :P

milli360
2004-Mar-16, 07:42 PM
Did I say object? I meant planet. :)

Lorcan Faol
2004-Mar-16, 08:03 PM
Awesome, this is one of the few threads where I understand everything that has been said so far... but I'm sure if I give it a few more hours, there will be something way over my head.

Ripper 2.0
2004-Mar-16, 08:19 PM
I think we need to face up to the fact that Sedna is not the smallest planet, it is just a really big comet.

Madcat
2004-Mar-16, 08:33 PM
Now we need to get a convenient star and knock it out of the Oort cloud... 8)

Eroica
2004-Mar-16, 08:37 PM
We finally have an object whose orbit actually looks like an ellipse!

uh, all orbits are ellipses.
Yeah, but most of them, if plotted, look like circles, possibly slightly offset from the origin.
Whence it follows logically that circles look like ellipses! 8)

StarStuff
2004-Mar-16, 08:43 PM
Awesome, this is one of the few threads where I understand everything that has been said so far... but I'm sure if I give it a few more hours, there will be something way over my head.

:lol: I know the feeling.... I'm hoping that if I hang around here for long enough, I'll be able to absorb some of the brilliance from other posters, just through osmosis.

Don't get me wrong - I really do love it here! :)

JohnOwens
2004-Mar-16, 10:55 PM
Did I say object? I meant planet. :)

You do know you're just digging yourself in deeper with that, right? :wink:

milli360
2004-Mar-17, 12:02 AM
You do know you're just digging yourself in deeper with that, right?
<suspicious>no, why?</suspicious>

bearcub
2004-Mar-17, 12:17 AM
I beleive that John's referring to the fact that Sedna's being called a planetoid, and doesn't qualify as a planet.