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A diagram of how arms form in spiral galaxies. I made it with the following Metapost program:
Linethickness = 3pt;
scale = 4in;
beginfig(1);
pickup pencircle scaled Linethickness;
for i = 0 upto 11 :
draw fullcircle scaled ((1 - i/12) * scale)
xscaled 1.6 rotated (-110/11 * i);
endfor;
currentpicture := currentpicture shifted (2*scale, scale);
endfig;
end;
Compile with mpost, open in Gimp, resolution 800, "try bounding box", gray, weak anti-aliasing. Crop, save as PNG.
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Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.
http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment |
| current | 04:41, 27 October 2005 |  | 4,373 × 2,744 (1.14 MB) | Dbenbenn | thumbnail, since MediaWiki won't thumbnail PNGs that are more than 12.5 megapixels |
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