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Date: 22 Sep 2006 21:25:57
From: Algomeysa2
Subject: Eris (the dwarf planet formerly known as Xena) in Starry Night
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In a bit of true armchair astronomy, I was trying to find Eris in my Starry
Night software. I'm still running "Backyard" (Version 3. I think), but
I've got the asteroids/comets/planets files updated.
Now, there's nothing under the name Eris in there, but i did find:
2003 UB313
Which is supposed to be its designation.
But Starry Night identifies that as only 10 AU right now, whereas the real
Eris ranges from 37.8 AU to 97.56 AU
Any tips? I could try to manually add it from the info on Wikipedia, but
I'm dubious that I'd do it all correctly.
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Date: 23 Sep 2006 00:17:11
From: Algomeysa2
Subject: Re: Eris (the dwarf planet formerly known as Xena) in Starry Night
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"Algomeysa2" <Algomeysa2NOSPAM@mindspring.comNOPESPAM > wrote in message
news:FxYQg.11047$v%4.7958@newsread1.news.pas.earthlink.net...
> In a bit of true armchair astronomy, I was trying to find Eris in my
> Starry Night software. I'm still running "Backyard" (Version 3. I
> think), but I've got the asteroids/comets/planets files updated.
>
> Now, there's nothing under the name Eris in there, but i did find:
> 2003 UB313
> Which is supposed to be its designation.
>
> But Starry Night identifies that as only 10 AU right now, whereas the real
> Eris ranges from 37.8 AU to 97.56 AU
>
> Any tips? I could try to manually add it from the info on Wikipedia,
> but I'm dubious that I'd do it all correctly.
Continued from before:
I'm running Starry Night Backyard (version 3).
Using wikipedia, I attempted to plug in the data for Eris/Xena/2003 UB 313
Here's what I put in Starry Night as a new planetoid:
Style: Near Circular
Reference Plane: Eliptic 2000
Mean Distance: 67.6681000 AU
Eccentricity: 0.4417700
Inclination: 44.1870000
Ascending Node: 35.8696000
Arg of pericenter: 115.5609000
Mean anomaly: 197.6342700
Epoch: 2453800.5000 JD
This seemed to result in approximately:
aphelion - February 25, 1979 AD - 98.33 AU
perihelion - February 22, 2254 AD - 37.09 AU
(Wikipedia lists aphelion at 97.56 AU and perihelion at 37.8 AU, so at least
it's in the ballpark)
Anyone know, are these dates within a horseshoes and handgrenades throw of
being correct?
(Say, a decade or so).
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Date: 23 Sep 2006 07:13:07
From: Paul Schlyter
Subject: Re: Eris (the dwarf planet formerly known as Xena) in Starry Night
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In article <b2%Qg.11083$v%4.5438@newsread1.news.pas.earthlink.net >,
Algomeysa2 <Algomeysa2NOSPAM@mindspring.comNOPESPAM > wrote:
> Using wikipedia, I attempted to plug in the data for Eris/Xena/2003 UB 313
>
> Here's what I put in Starry Night as a new planetoid:
>
> Style: Near Circular
> Reference Plane: Eliptic 2000
> Mean Distance: 67.6681000 AU
> Eccentricity: 0.4417700
> Inclination: 44.1870000
> Ascending Node: 35.8696000
> Arg of pericenter: 115.5609000
> Mean anomaly: 197.6342700
> Epoch: 2453800.5000 JD
>
> This seemed to result in approximately:
>
> aphelion - February 25, 1979 AD - 98.33 AU
> perihelion - February 22, 2254 AD - 37.09 AU
>
> (Wikipedia lists aphelion at 97.56 AU and perihelion at 37.8 AU, so at least
> it's in the ballpark)
>
> Anyone know, are these dates within a horseshoes and handgrenades throw of
> being correct?
No way !!!!
How far can you throw a horseshoe or handgrenade? 50 yards? That's
as little as some 0.0000000003 AU - the mean distance above is given
only to a precision of 0.0001 AU. Which means the inaccuracy of the
computed position of Eris is many millions of horseshoe/handgrenade
throws.....
--
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Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/
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