Slika:Galilean moon Laplace resonance animation.gif

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Galilean_moon_Laplace_resonance_animation.gif ‎(365 × 245 točk, velikost datoteke: 351 KB, MIME-vrsta: image/gif, ponavljajoče, 288 sličic, 5,8 s)

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Povzetek

Opis	English: Animation of the 1:2:4 Laplace resonance between Io, Europa, and Ganymede. The labels indicate the ratios of orbital periods: Europa's is twice Io's, and Ganymede's is four times Io's. Warning: do not downsize the image below its original size of 365 × 245 when used in a Wikipedia article, as the animation won't move then (at least not for all users).
Datum	16. februarja 2011 ob 18:10 (UTC)
Vir	based on earlier version of this file, avail. below
Avtor	User:Matma Rex
Dovoljenje (Nadaljnja uporaba datoteke)	Public Domain
Druge različice	Deutsch Latin English .SVG Français .SVG Edited version with conjunctions highlighted by color changes

Licenca

Jaz, imetnik avtorskih pravic na tem delu, izročam to delo v javno domeno. To velja po vsem svetu.
V nekaterih državah to pravno morda ni mogoče. Če je tako,
Vsakomur dajem (v okviru zakonskih omejitev) brezpogojno pravico, da gradivo uporablja v kateri koli namen.

Generation

This image has been generated by the following Ruby code and optimized in GIMP.

# author: Matma Rex
# code licensed under CC-BY-SA license

require 'rubygems'
require 'RMagick'
include Magick



step=5 # degrees by which Io will move in every frame


# Io, Europa, Ganymede
distances=[46, 72, 112]
speeds=[1, 0.5, 0.25]
shifts=[-90, 90, -90]

centerx=122
centery=122



list=ImageList.new

base=Image.new 365,245
base.ticks_per_second=1000
base.delay=5*step


gc=Draw.new

# lines
gc.stroke 'lightgrey'
gc.stroke_width 1.5
distances.each{|d| gc.line centerx, centery-d, 360, centery-d}
gc.line centerx, centery, 360, centery

# orbits
gc.stroke 'grey'
gc.fill 'none'
gc.stroke_width 2
distances.each{|d| gc.circle centerx, centery, centerx, centery+d}

# Jupiter
gc.stroke 'black'
gc.fill 'black'
gc.stroke_width 2
gc.circle  centerx, centery, centerx, centery+9

# labels
# gc.stroke_width 0
# gc.gravity EastGravity
# gc.font_family 'arial'
# gc.font_size 18
# gc.font_weight LighterWeight
# gc.text_align RightAlign
# gc.text_undercolor 'white'

# gc.text 360, centery-distances[0]+7, '"  Io 1:1"'.upcase
# gc.text 360, centery-distances[1]+7, '"  Europa 2:1"'.upcase
# gc.text 360, centery-distances[2]+7, '"  Ganymede 4:1"'.upcase

# gc.font_weight BoldWeight
# gc.text 360, centery+7, '"  Jupiter"'.upcase


gc.draw base

# ImageMagick sucks at text - load a predefined text img instead
base=base.composite Image.read('text.png')[0].transparent('cyan'), 0, 0, OverCompositeOp



(0..(4*360-1)).step(step) do |deg|
  img=base.clone
  gc=Draw.new

  0.upto(2) do |i|
    rad=(deg*speeds[i] + shifts[i]) * Math::PI / 180.0
  
    x=distances[i] * -Math.cos(rad)
    y=distances[i] * Math.sin(rad)

    gc.circle centerx+x, centery+y,  centerx+x, centery+y+4.5
  end

  gc.draw img
  
  list << img
end

list.write 'magick.gif'

Zgodovina datoteke

Kliknite datum in čas za ogled datoteke, ki je bila takrat naložena.

	Datum in čas	Velikost	Uporabnik	Komentar
trenutno	20:08, 16. februar 2011	365 × 245 (351 KB)	Matma Rex	a much nicer version, even if somewhat larger
	20:33, 23. december 2010	365 × 245 (21 KB)	Bark~commonswiki	Changed direction from clockwise to counter-clockwise to better represent the Jovian system with the view from above the north pole, the typical convention. The previous version accidentally implied retrograde motion in the system, which is not the case.
	10:17, 3. november 2006	365 × 245 (32 KB)	Splarka	{{Information \|Description=Animation of the 4:2:1 Laplace resonance between Ganymede, Europa, and Io \|Source=created for Wikimedia \|Date=~~~~~ \|Author=User:Splarka \|Permission=Public Domain \|other_versions=This is the first }}