The Sun is larger than a satellite and, more importantly, it has a larger visible size. That is, if a satellite (even ISS) passed right before the Sun, it would look like a tiny speck on its disk, since satellites fly at altitudes over 100 km. So a satellite simply cannot block the Sun completely, meaning no shadow. Or, more precisely, the satellite’s shadow only goes for a few kilometers below it, down to a point from which it becomes small enough to not be able to block the Sun completely.
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