Condensation trails or 'con trails'.
The sky
A formation
A radar tracks aircraft in the sky
Gas comes out of airplanes, which causes air pollution, and sometimes changes the sky color.
a radar
Sky magazine is published by delta airlines as a service to their customers. I have found no connection between sky online and sky magazine.
The engines create smoke .
Some people have drawn things in the sky with airplanes, some gas or smoke but its only temporary.
-- stars -- meteors -- airplanes.
??Why is your name your name and why are you alive?? Exactly that's just a name they made!!
exhaust
Aerial photography