Link:
http://ssd.jpl.nasa.gov/?horizons
Using this tool I am able to retrieve information to model the planets'
orbits. But what about the rotation of the planets? It gives information
about rotational speed as well as obliquity WRT the xy plane, but AFAIK
doesn't give the necessary information the direction of the obliquity,
or the side of the planet that is facing the "front" at the given epoch.
Did I miss something? Where can I dig up this info?
--
http://isometricland.com
From: Invisible
Subject: Re: JPL's HORIZONS system
Date: 30 Jun 2010 04:00:54
Message: <4c2af9b6$1@news.povray.org>
SharkD wrote:
> Using this tool I am able to retrieve information to model the planets' > orbits. But what about the rotation of the planets?> > Did I miss something? Where can I dig up this info?
You could try prodding Wolfram Alpha just for giggles. It might
conceivably have the data you want. (Assuming you can guess what the
correct query string is...)
From: SharkD
Subject: Re: JPL's HORIZONS system
Date: 30 Jun 2010 22:03:31
Message: <4c2bf773$1@news.povray.org>
On 6/30/2010 4:00 AM, Invisible wrote:
> SharkD wrote:>>> Using this tool I am able to retrieve information to model the>> planets' orbits. But what about the rotation of the planets?>>>> Did I miss something? Where can I dig up this info?>> You could try prodding Wolfram Alpha just for giggles. It might> conceivably have the data you want. (Assuming you can guess what the> correct query string is...)
As for the starting rotation amounts, I've come up with the following
scheme:
1. I already have a set of stored dates for when each planet was last at
perihelion which I can reuse.
2. On HORIZONS I look up what the local sidereal time was at the
planet's meridian on that same date.
3. I rotate the planet to match the local sidereal time.
4. I calculate the difference between the stored perihelion date and
today's date.
5. I rotate the planet even more to match today's date.
Hopefully, I am understanding the parameters and how they should be used
correctly.
--
http://isometricland.com
On 6/30/2010 4:00 AM, Invisible wrote:
> SharkD wrote:>>> Using this tool I am able to retrieve information to model the>> planets' orbits. But what about the rotation of the planets?>>>> Did I miss something? Where can I dig up this info?>> You could try prodding Wolfram Alpha just for giggles. It might> conceivably have the data you want. (Assuming you can guess what the> correct query string is...)
No luck on Wolfram either.
--
http://isometricland.com
From: Orchid XP v8
Subject: Re: JPL's HORIZONS system
Date: 2 Jul 2010 16:41:18
Message: <4c2e4eee$1@news.povray.org>
>> You could try prodding Wolfram Alpha just for giggles. It might>> conceivably have the data you want. (Assuming you can guess what the>> correct query string is...)> > No luck on Wolfram either.
Oh well - it was worth a shot...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
