xtcg123

What's the smallest object you could clearly see/read on the ground from typical SR-71 altitude?

Is it true the SR-71 could navigate by using stars, even during the day? How does that work?

Is there anything like that in other airplanes? How could it 'see' the stars in the daytime? Wouldn't it have to be a visual system, where clouds, etc could get in the way at the lower altitudes?