Bringing out features in an astronomy photo

[rich2005]

Since you are using a Mac, probably confined to standard Gimp tools (although it looks like the partha version has gmic plugin which has a few more options).

Either way, not getting far with that photograph, nowhere near the wiki photo.

Maybe.
Colours -> Auto -> Stretch Contrast HSV then Colours -> Curves pull the colour up to try and bring out the clouds.
example: https://i.imgur.com/KMvqssl.jpg

There will be other/better ways