When are you in the sky? There are the obvious times: in an...

When are you in the sky? There are the obvious times: in an
airplane; a hot air balloon; a rocket; the moment of peak height after
being launched from a diving board. But if you are in a room on the
second floor and lean out the window and trees outside your window are
taller than the roof, are you in the sky? What distance must one travel up to meet it? Is there a
scientific measure with numbers and variables and exponents riding the
shoulders of the regular-size numbers? Does an equation exist? Sky =
11.19 squared over weather to the third times Time times light times
height of person measuring minus birds? Does an invisible band like the
Tropic of Capricorn trace a line above, an invisible eggshell of
guarantee that delineates: this is sky, this is not sky?

For the Paris Review Daily, I’m writing a six-part series about the sky. The first one asks where does the sky start?