Hang on, a vapour trail? Haven't seen one of those in ages.
I used to despair of ever seeing the sky the way our ancestors saw it- without planes or their detritus- and now emptiness is the norm.
Talking about "unravelling" I see we now know the Neanderthals used string- because a tiny fragment of the stuff has turned up at one of their sites in the Rhone Valley. It's made of the fibrous backside of tree bark. So now we can picture them carrying string bags and wearing string vests and doing up parcels and you name it. This is the sort of news story that makes me happy.