Celestia Forums

Posted: **13.08.2006, 10:47**

Is it possible to simulate the Lunar Libration
similar to this animation:

http://en.wikipedia.org/wiki/Image:Luna ... phase2.gif

perhaps using some script ??
Maybe someone has done this already .

Ren?©

Posted: **13.08.2006, 12:12**

rra wrote:Is it possible to simulate the Lunar Libration similar to this animation:
http://en.wikipedia.org/wiki/Image:Luna ... phase2.gif
perhaps using some script ?? Maybe someone has done this already .
Ren?©

Ren??, in my "Moon Tour" cel script I show it in this way:

Code: Select all

select { object "Sol/Earth/Moon" } 
time { jd 2453794.5 } 
timerate {rate 0.0}
gotolonglat {time 3.0 distance 28 longitude 0.0 latitude 0.0}
synchronous {} 
wait {duration 3.0}
print {text "We show you a full\nlunation with 1 day intervals" row -5 column 1 duration 8.0}
wait {duration 8.0}
time { jd 2453794.305 }
wait {duration 0.8}
print {text "New Moon" origin "center" row 10 column -4 duration 2.0}
wait {duration 2.0}
time { jd 2453795.75 } 
wait {duration 0.8}
time { jd 2453796.75 } 
wait {duration 0.8}
time { jd 2453797.75 } 
wait {duration 0.8}
time { jd 2453798.75 } 
wait {duration 0.8}
time { jd 2453799.75 } 
wait {duration 0.8}
time { jd 2453800.75 } 
wait {duration 0.8}
time { jd 2453801.75 } 
wait {duration 0.8}
print {text "First Quarter " origin "center" row 10 column -5 duration 2.0}
wait {duration 2.0}
time { jd 2453802.75 } 
wait {duration 0.8}
time { jd 2453803.75 } 
wait {duration 0.8}
time { jd 2453804.75 } 
wait {duration 0.8}
time { jd 2453805.75 } 
wait {duration 0.8}
time { jd 2453806.75 } 
wait {duration 0.8}
time { jd 2453807.75 } 
wait {duration 0.8}
time { jd 2453808.75 } 
wait {duration 0.8}
print {text "Full Moon" origin "center" row 10 column -4 duration 2.0}
wait {duration 2.0}
time { jd 2453809.75 } 
wait {duration 0.8}
time { jd 2453810.75 } 
wait {duration 0.8}
time { jd 2453811.75 } 
wait {duration 0.8}
time { jd 2453812.75 } 
wait {duration 0.8}
time { jd 2453813.75 } 
wait {duration 0.8}
time { jd 2453814.75 } 
wait {duration 0.8}
time { jd 2453815.75 } 
wait {duration 0.8}
time { jd 2453816.75 } 
wait {duration 0.8}
print {text "Third Quarter " origin "center" row 10 column -5 duration 2.0}
wait {duration 2.0}
time { jd 2453817.75 } 
wait {duration 0.8}
time { jd 2453818.75 } 
wait {duration 0.8}
time { jd 2453819.75 } 
wait {duration 0.8}
time { jd 2453820.75 } 
wait {duration 0.8}
time { jd 2453821.75 } 
wait {duration 0.8}
time { jd 2453822.75 } 
wait {duration 0.8}
time { jd 2453824.0 } 
wait {duration 0.8}
time { jd 2453826.65 }    
wait {duration 0.8}
print {text "New Moon" origin "center" row 10 column -4 duration 2.0}
wait {duration 2.0}

Enjoy.

ADDED LATER: :oops:

Sorry for misunderstanding, I missed you was searching for the libration effect. :oops:

Here is my libration cel script, that needs Vincent's patch and the images (that I took from the same address you gave):

Code: Select all

print {text "Two lunar phenomena due to Moon\nmovements: dimensional variation and libration" row -4 column 1 duration 6.0}
wait {duration 6.0}
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 08).jpg" }
wait { duration 0.6 }
overlay { duration 0.6 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 09).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 10).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 11).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 12).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 13).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 14).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 15).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 16).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 17).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 18).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 19).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 20).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 21).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 22).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 24).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 26).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 28).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 30).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 32).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 34).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 36).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 38).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 40).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 42).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 44).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 46).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 48).jpg" }
wait { duration 0.6 }
overlay { duration 1.0 xoffset 0 yoffset 0.50 alpha 1.0 filename "Lunar_libration_with_phase2(Frame 50).jpg" }
wait { duration 1.5 }

Hope this solves the problem. :wink:

Bye

Andrea

Posted: **13.08.2006, 14:57**

Andrea,
thanks for your help,
but I was really looking (hoping) for something smoother,
and (high-res) images generated from within Celestia,
something like your first tour, but then with smaller steps.
I guess I can construct my own CEL script starting from yours.
But then again, the libration effect won't be visible.
Any other ideas, or links to moon-scripts ?

By the way:
how/where did you extract the libration-images from Wikipedia ?

Ren?©

Posted: **13.08.2006, 15:48**

rra,

I'm not sure why you say the libration effect won't be visible. You should certainly be able to see it by using Andrea's script to view 28 daily images of the Moon and taking screenshots of them if you want. If you position your viewpoint at the center of the Earth,Track the Moon and turn up the simulation time rate, you could get an even smoother display. Celestia shows the Moon's orbit and rotation correctly.

The English Wikipedia page is at
http://en.wikipedia.org/wiki/Libration

Posted: **13.08.2006, 16:53**

selden wrote:If you position your viewpoint at the center of the Earth,Track the Moon and turn up the simulation time rate, you could get an even smoother display. Celestia shows the Moon's orbit and rotation correctly.

Here's what Selden's taking about: Click here

I get about 40fps, that should be smooth enough. :wink:

Watch out for transits of the Sun.

Posted: **13.08.2006, 17:19**

rra wrote:Andrea, thanks for your help, but I was really looking (hoping) for something smoother, and (high-res) images generated from within Celestia.

Ren??. Selden and Chuft-Captain gave you the right answer. :wink:

rra wrote:By the way: how/where did you extract the libration-images from Wikipedia ?
Ren?©

I don't remember exactly, it was time ago, but I think I took the movie from another site, and extracted the needed images with Selteco Bannershop GIF Animator.

Hope this helps.
Bye

Andrea

Posted: **13.08.2006, 17:59**

Chuft-Captain wrote:Here's what Selden's taking about: Click here

I get about 40fps, that should be smooth enough.
Watch out for transits of the Sun.

Well, I get about 15 fps (><; ), but it's still pretty neat to watch. It looks almost exactly like that .gif. neato

Posted: **13.08.2006, 18:56**

Something rather interesting happens after the year 4000 ----> See if you can spot it<--- click this

Posted: **13.08.2006, 19:10**

Posted: **14.08.2006, 20:02**

trying to do this same trick on other moons ,
I still have difficulties in "going to the center" of the object (planet).
How can I, generally speaking, go to the center of a planet ?

Ren?©

Posted: **19.08.2006, 11:32**

Ren?©,

I'm sorry for the delay in getting back to you.

What I do to get inside an object is to define a second invisible one with a much smaller radius but with the same orbital parameters and then GoTo that new object.

e.g.

Code: Select all

"centerEarth" "Sol" {
        Class "invisible"
   Radius 0.01
   
   CustomOrbit "vsop87-earth"
   
   RotationPeriod    23.9344694 
   Obliquity           -23.45
   RotationOffset   280.5 

   Albedo            0.001
}

Posted: **19.08.2006, 19:25**

Selden,
when I apply your previous suggstion

if you position your viewpoint at the center of the Earth,Track the Moon and turn up the simulation time rate, you could get an even smoother display.

I see the lunar Libration effect but frequently the view to the moon is
disturbed by the earth itself I think.
I don't know why the cel:url link of Chuft-Captain doesn't have this effect.
If I add your code, I guess the view won't be disturbed.
I'll experiment a bit the coming days.
Thanks ,

Ren?©

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