Bestand:Galilean moon Laplace resonance animation.gif

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Galilean_moon_Laplace_resonance_animation.gif ‎(365 × 245 pixels, bestandsgrootte: 351 kB, MIME-type: image/gif, herhalend, 288 frames, 5,8 s)

Dit is een bestand van Wikimedia Commons.
Onderstaande beschrijving komt van de beschrijving van het bestand daar.

Beschrijving

Beschrijving	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 februari 2011, 18:10 (UTC)
Bron	based on earlier version of this file, avail. below
Auteur	User:Matma Rex
Toestemming (Hergebruik van dit bestand)	Public Domain
Andere versies	Deutsch Latin English .SVG Français .SVG Edited version with conjunctions highlighted by color changes

Licentie

Ik, de auteursrechthebbende van dit werk, geef dit werk vrij in het publieke domein. Dit is wereldwijd van toepassing.
In sommige landen is dit wettelijk niet mogelijk; in die gevallen geldt:
Ik sta iedereen toe dit werk voor eender welk doel te gebruiken, zonder enige voorwaarden, tenzij zulke voorwaarden door de wet worden voorgeschreven.

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'

Bestandsgeschiedenis

Klik op een datum/tijd om het bestand te zien zoals het destijds was.

	Datum/tijd	Afmetingen	Gebruiker	Opmerking
huidige versie	16 feb 2011 20:08	365 × 245 (351 kB)	Matma Rex	a much nicer version, even if somewhat larger
	23 dec 2010 20:33	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.
	3 nov 2006 10:17	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 }}