Subject: Re: Why is ISS still visible in Earth's shadow? > I've been thinking about this for some time. Just how bright is a city as > seen from LEO? It's not an easy question since we're dealing with a light > source that has a very large angular size. Then again, cities at night are > popular photography targets for the ISS astronauts while photos of stars > and constellations are almost non-existent. So maybe there are clues there Actually, the lack of true astrophotos taken from the space station is more a reflection on the fact that most astronauts are not amateur astronomers and are not interested in astrophotography. And the challenges of photographing the stars from an unstable (as compared to Hubble) platform in Earth orbit with off-the-shelf equipment available on the station are quite large. One astronaut who is an amateur astronomer and did quite a bit of astrophotgraphy, as well as the pioneering work on high-resolution city at night photography, was Don Pettit on Expedition 6. A 10 minute video Don produced himself of his cities at night work can be seen on YouTube at http://www.youtube.com/watch?v=U7WuSP663uU His work started an extensive database for measuring and characterizing urban brightness. I have no doubt that the night time glare of a major metropolis can sufficiently illuminate the ISS to make it telescopically detectable within Earth's shadow, but don't have the math to calculate the expected magnitude. I suspect it would be 8th or 9th...a challenge without automated scope tracking. I am looking forward to his flight back to the station in November when he will again continue his photography with better cameras than the clunky Kodak digital they had in 2002. Robert Reeves San Antonio, Texas Planet 26591 www.robertreeves.com reeves10@satx.rr.com _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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