[amsat-bb] ARISSat in sunlight

John Heath g7hia at btinternet.com
Sun Sep 25 12:18:54 PDT 2011

Interesting thread regarding  MET and ARISSat-1 switch on.
Someone made the very good point that the transition in or out of sunlight 
(eclipse) is not an on/off event. I remember many MIR visuals, and as she passed 
from sunlight in the west to darkness in the east there was a significant time, 
perhaps a minute or more when she changed colour from bright and silver white to 
orange then disappeared into blackness. I always interpreted that as passing 
through the penumbra, or semi shadow area.
ARRISat-1 is at at around 370km, does anyone know how to find the width of the 
penumbra  at that altitude?
Working out the transit time through that region might be informative.
73 John G7HIA

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