SEEING A DISHWASHER - 300KM AWAY
Here are my thoughts, anonjedi - on the top of my head. However 'unscientific' the following little discourse may be, I hope it may be considered as a fair / reasonable / no-nonsense reality-check of the optical implications of :
"Seeing with our bare eyes a dishwasher-sized object at a distance of about 300km".
To be sure, we are told that most satellites are roughly dishwasher-sized, and that the closest ones fly at a minimum altitude of 300km:
So now, as the keen sky-gazer that I am, let me share with you my own / personal observations of how commercial airliners appear (to my eyes) in my skyline. I live nearby two busy airports and have a panoramic, hillside view of airliners descending towards them. Of course, none of the airliners I can readily spot with my eyes are flying at their standard cruising altitudes (about 10km) - they are much lower than that, since they are approaching the airports and are about to land.
As it is, over the years I have come to the conclusion that those that DO fly over my garden at cruise altitudes (on totally clear, cloudless days, that is) are invisible to my bare eye. Only today in fact, (and as I have experienced on countless occasions), I again heard a faint jet sound overhead as I strolled in my garden. I looked up and scoured the pristine, absolutely cloudless blue sky - but could not for the life of me
spot that airliner flying above me (I have excellent eyesight, btw). But let me now get on with my thought exercise.
Here's a dishwasher (about the size of most of NASA's / ESA's alleged man-made satellites):
Here is a stock image (not mine) of an airliner - most likely captured in its descending phase (Yes, I know - I don't know at what exact altitude it was flying as this picture was taken - so please bear with my approximating ways - for the sake of this optical thought exercise). Note that I have 'attached' (in Photoshop) the yellow dishwasher underneath the plane's cockpit (to see it, you can enlarge this image by holding ctrl+ on most keyboards). Note also that I've been quite generous with the size / proportions of the yellow dishwasher:
Now, let me postulate that with a really big-ass / professional telephoto lens (such as this Canon 1000mm
one could possibly take this sort of picture of an airliner cruising at 10km of altitude. Again, I am being 'generous' here - as to the lens-view size of the plane flying at such a height:
Here, I have shrunk that airplane image by a factor of 10, so this is roughly what the airliner would look like (in the big telephoto lens) if it were cruising at 100km of altitude:
Here, I have shrunk the above airplane to 1/3 of the above image - so this is roughly what the airliner would look like (in the big telephoto lens) if it were cruising at 300km of altitude (the minimum altitude we are told man-made satellites fly at):
Now, take away the big telephoto lens and imagine being able to see the yellow dishwasher with your bare eyes.