Huh? The Nebulae were beautiful and therefore they exist? I'm confused lol.
You are confusing physical truth with philosophical truth.
Im really not going to go into detail here, in the age of google.
Suffice it to say that fantasy is a human representation of reality, not reality.
It does not hold to the same laws.
The most important law it does hold to is that it needs to be a story.
(reality often isnt a story, thats why people invented journalists, to tell us theres a story there
Cat stuck up tree isnt a story. Fireman heroically saves dear pet IS)
For a good story to be cathing it needs to hold true to certain human addages.
It is Beautiful and therefore true is a very strong one.
By golly gosh I did go all explainy.