Nebula
A nebula is a distinct part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. The word also refers to a galaxy other than the Milky Way. (taken from MiriamWebster.com)
Used in a sentence - We were eventually able to see the nebula through the telescope. The closest known nebula to Earth, is the Helix-Nebula.
In English, the word “nebulous” has evolved to describe things that aren’t clear or well-defined, like how a cloud can sometimes obscure our visibility. It’s also used to describe abstract concepts and ideas.
I think “Helix Nebula” would be a great name for a cat, actually.