>> Has anyone tried to view the ISS in shadow through a guided telescope? > Up to ~40 seconds after shadow entry on passes directly over > Phoenix, AZ. Assumed reflected city lighting. It's hard to say (without writing a computer program to calculate it) precisely what "after shadow" means, because of the earth's atmosphere. It's fairly well known (among amateur astronomer types) that at sea-level, etc., a "horizontal" light ray has been refracted by about 35 minutes of arc, so that the setting sun/moon (having a diameter of about 30 minutes of arc) is in fact entirely below the physical (i.e., unrefracted) horizon when it first begins to "set." So the atmosphere acts somewhat as a lens (or prism), bending the light from the sun into what would otherwise be "shadow." Another important consideration is the fact that the sun is "pretty big" (i.e., it isn't like a laser beam, or a "point source of light"), so that- even without atmospheric lensing- the earth's "shadow" would not be sharp. ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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