Re: ISS observation

From: Jeff Umbarger (
Date: Thu May 29 2008 - 03:24:27 UTC

  • Next message: Ted Molczan: "TJM obs of 2008 May 29 UTC"

    Maybe if the part of the earth directly below the
    setting (or rising) Sun from the ISS point of view was
    ocean,  you might get a strong secondary light source
    (the reflected image of the Sun). But if it were land
    I would think the it would be a much weaker light
    source then the Sun. Interesting spherical geometry
    problem - if you assume the earth a mirrored sphere
    and the Sun a "few" degrees above the limb of the
    earth from the spacecraft position, where would the
    "reflected" image of the Sun appear on the earth's
    mirrored surface from the perspective of the
    spacecraft? And at some Sun elevation, that point is
    in darkness as seen from the spacecraft. Where do you
    live Dale? If it's the West Coast (Pacific), Florida
    (Gulf of Mexico), it might explain something for an
    evening pass.
              Jeff Umbarger
              Plano, TX USA
    --- Gerhard HOLTKAMP <> wrote:
    > On Tuesday 27 May 2008 05:13, Dale Ireland wrote:
    > > I was amazed last evening at how bright the ISS
    > appeared in a pass with the
    > > Sun only 2.5 degrees below the horizon,
    > practically daylight. I will have to
    > > try it on a pass with the Sun still just above the
    > horizon. It had to be -5
    > > or better.
    > > 
    > On a number of occasions I had the impression that
    > the ISS and in years past 
    > the Mir were particularly bright just after sunset.
    > Maybe is has to do with 
    > extra reflections from the still illuminated part of
    > the Earth surface. (Is 
    > there any satellite tracking software which models
    > this effect?)
    > Gerhard HOLTKAMP
    > Darmstadt, Germany
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