I spent a lot of time watching the sky when I was a kid. Because I was only a few miles from an airport, planes were often in view during my sky gazing. The planes always looked so white, looking up into the light as I did, that I called them “ghost planes”. Leave it to a kid to bring imagination into an everyday happening. Leave it to a kid to also be observant.
One thing I can tell you about the planes is that not all of the planes left trails. The ones that did, left a trail that disappeared about a hand-width back. Hand-width, being the size of a ten-year old girl’s hand placed arm-distance from the eyes towards the sky.
This girl still does sky gazing, but has noticed quite a change in recent years. And this is just from this morning.
What do you observe when you look around? Be aware of your environment and the changes you see. Look with the eyes of a kid.