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Cosmic "Analemma" (Read 2977 times)
frankuitaalst
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Cosmic "Analemma"
12/02/07 at 11:36:24
 
A special kind of depicting an orbit of a celestial body is to represent it on the celestial globe in terms of it's latitude and altitude to the zero point of Aries .  
The zero point of Aries is used as the reference in the JPL ephermeris.  
Suppose you are an observer on Earth ( more exactly at the center of earth ) , and always look towards  the zero point of Aries .
What movement would planets show ?  
Herunder is a picture of what one might see if he depicts the orbit of Saturn .  
Longitude (-180° to 180° ) is represented from left to right .  
Altitude (90° to -90°) is represented from top to bottom .  
( in order to improve the representation the altitude is exagerated by a factor of 10) .  
In this view one can see the "retrograde" motion of Saturn along the sky .  
This is due to the motion of Earth around the sun.  
Simulation was run for 30 years.  
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Saturnanalemma.gif
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Tony
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Re: Cosmic "Analemma"
Reply #1 - 12/03/07 at 15:49:59
 
It took me a little while to figure this one out, but this is facinating, especially the retrograde motion.  Thanks, Frank. Cool
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frankuitaalst
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Re: Cosmic "Analemma"
Reply #2 - 12/04/07 at 11:25:52
 
Herunder is a simulation from the same vieuwpoint showing the orbit of Jupiter . Interval between each frame is 1 year.
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JupiterAnalemma.gif
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frankuitaalst
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Re: Cosmic "Analemma"
Reply #3 - 12/04/07 at 11:46:32
 
The planets Mars and Venus show an analog retrograde motion along the sky.  
Pictured hereunder is the motion of both planets for the next 50 years .  
Remarkable is that both planets exhibit 2 saddle regions in their orbit .  
No of the planets however will cross the zero point vieuwed from Earth in the next 50 years .
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MarsVenusAnalemma.gif
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frankuitaalst
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Re: Cosmic "Analemma"
Reply #4 - 12/08/07 at 01:37:04
 
Herunder is a simulation of the orbit of Apophis 2004MN4 asteroid in the same frame as above  
looking from Earth to the zero point of Aries .( Left to right : 360° longitude ; Top to bottom : 36° altitude ).  
As is mostly the case Apophis has two saddle regions , but also has a retrograde movement , "shooting" out of this saddles.
Retrograde movements correspond with the time in which the asteroid is close to earth.
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ApophisAna.gif
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frankuitaalst
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Celestial Path
Reply #5 - 12/29/07 at 03:09:39
 
Heres an animation of the path of "Earths second Moon" Cruithne, in te same coordinate system as above .  
The Y-axis was elongated .  
BTW : Is there some way to change the title : the pictures are not "Analemma" , "celestial path" should be a better name.
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« Last Edit: 12/29/07 at 16:09:52 by frankuitaalst »  

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Tony
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Re: Cosmic "Analemma"
Reply #6 - 12/29/07 at 13:02:49
 
Quote from frankuitaalst on 12/29/07 at 03:09:39:
...
BTW : Is there some way to change the title : the pictures are not "Analemma" , "celestial path" should be a better name.

You should be able to use the "Modify" button on your original post.
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