Robert D. Anderson 2005
"Star trails" of Orion (red trail is M42 nebula)
"star trail" image to show stars have different colours. Camera lens slightly defocussed to increase thickness of star-trails.
Link to send via email/instant messenger:
http://public.fotki.com/ROBERT1010/scitech/oriontrailse.html
Code for a Fotki Journal:
[photo id=gwsrksbsftrtgdxttwrrbwsqktf type=vi style=1 align=no link=photo]
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http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html#photmcolhuman