Re: ISS to be visible in daylit skies (?)

From: FrankReedCT@aol.com
Date: Sun Jul 16 2006 - 18:03:43 EDT

  • Next message: Marco Langbroek: "Obs ML (4353), 16 Jul 2006: USA 161, Lacrosse 3, IGS 1B"

    I think it's a bit of a p.r. exaggeration. Total  cross-sectional area will 
    roughly double when the remaining large components are  added to the ISS. That 
    corresponds to a brightess change of about one magnitude.  Not really a big 
    deal. So can you see it in daylight? Sure. And you can now,  too, but you need 
    excellent eyes, exact knowledge of its position in the sky for  every moment of 
    time, and crystal-clear skies.
    
    There's another way to  analyze this. As far as its visual properties are 
    concerned, the ISS is directly  analogous to an aircraft in sunlight --but one 
    without a contrail behind it. How  large an aircraft does it correspond to? The 
    ISS is about 250 feet across (very  roughly) at a height of about 250 miles. 
    So for a comparable aircraft, consider  one that is 2.5 feet across at at an 
    altitude of 13,000 feet (2.5 miles). That  will have the same angular size as 
    the ISS. Do you think you can see a model  airplane, or a seagull, flying above 
    you at an altitude of 13,000 feet in  daylight? Sure you can... with excellent 
    eyes, exact knowledge of its position,  and crystal-clear skies. The odds are 
    against it.
    
    -FER
    42.0N 87.7W, or  41.4N 72.1W.
    www.HistoricalAtlas.com/lunars  
    
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