There was a near perfect ISS flyby over Sydney today after sunset. A mag-3.5 overhead at 87 degree according to heavens-above. As always I really enjoyed watching it but I swear I could, at the same time, hear a constant kind of humming sound of low frequency, kind like that of a propeller but a lot smoother. My question is: is it possible to HEAR a ISS flyby? I have watched numerous ISS flyby before and they were all silent.
