Aurora is a marvelous phenomenon caused by the interaction between strong solar wind and magnetosphere around the earth.
Image source: https://science.nasa.gov/flag-shaped-aurora-over-sweden
We're given an image of an aurora:
A simple command reveals our flag:
$ strings Aurora.jpg | grep flag
flag{6e4ut1fuL_Aur0r4}
There it is, localized entirely within this CTF: flag{6e4ut1fuL_Aur0r4}.