Re: Flares from Nadir normal surfaces

Bjoern Gimle (
Sun, 8 Mar 1998 16:15:28 +0100

>Russell stated that for a satellite with a nadir-pointing surface to give 
>a reflection, the Sun will be the same elevation below the horizon that
>the satellite is above it (and in the same azimuth). 
>These comments aren't quite correct, but are an approximation for low
>satellites close to the observer (a flat Earth assumption).  I discussed
>the geometry of Sun-pointing and nadir-pointing surfaces in "Reflections
>on the flat surfaces of satellites" in Space 16/82 (30 Apr 1982); the
I haven't checked the references, nor the reasoning in the mails that
followed Russell's, but to me it seems it wouldn't flare:

Looking from the satellite, the Sun would have to have a zenith angle
greater than 90, but still above the true horizon.

The reflection from the nadir-normal surface will proceed in the same
azimuth, with the same zenith angle, i.e. it will pass above the
horizon, as did the incoming sun rays, and not hit Earth.

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