I have something of an interest in astronomy. I also have a 5" reflector telescope, plus of course binoculars. With the recent coronavirus emergency, a large number of commercial aircraft were grounded. It seemed to me that the skies were much clearer as a result. Now the planes are flying again, and the opposite seems to be true. Is this just my imagination, or pot luck? Do commercial aircraft have an effect on the clarity of the night-time sky?