Fil:Galilean moon Laplace resonance animation.gif

Det finns ingen version med högre upplösning.

Galilean_moon_Laplace_resonance_animation.gif ‎(365 × 245 pixlar, filstorlek: 351 kbyte, MIME-typ: image/gif, upprepad, 288 bildrutor, 5,8 s)

Denna fil tillhandahålls av Wikimedia Commons. Informationen nedan är kopierad från dess filbeskrivningssida.

Sammanfattning

Beskrivning	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)
Källa	based on earlier version of this file, avail. below
Skapare	User:Matma Rex
Tillstånd (Återanvändning av denna fil)	Public Domain
Andra versioner	Deutsch Latin English .SVG Français .SVG Edited version with conjunctions highlighted by color changes

Licensiering

Jag, upphovsrättsinnehavaren till detta verk, släpper detta verk i public domain. Detta gäller globalt.
I vissa länder kan detta inte vara juridiskt möjligt; i så fall:
Jag ger härmed envar rätten att använda detta verk för alla ändamål, utan några villkor, förutom villkor som lagen ställer.

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'

Filhistorik

Klicka på ett datum/klockslag för att se filen som den såg ut då.

	Datum/Tid	Dimensioner	Användare	Kommentar
nuvarande	16 februari 2011 kl. 20.08	365 × 245 (351 kbyte)	Matma Rex	a much nicer version, even if somewhat larger
	23 december 2010 kl. 20.33	365 × 245 (21 kbyte)	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 november 2006 kl. 10.17	365 × 245 (32 kbyte)	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 }}