A big part of pixel art is trying to keep a colour count as low as possible without affecting the quality of the art. This piece would probably look the same with around 12 colours. It isn't necessarily important, but it's good practice to keep a palette for both the making of the art and if the art is being used in a game etc.
But anyway - this piece is great, I really like it.
So, i think that the reason of number of colors is colour noise which became the source of small multi coloured stars. But even so, 537 is too many. Is it so important?
Brace yourselves... the Color Count posts are coming!!!
I did that 'image spec' tool on this and it says 537 colors... surely that can't be right?
This is gorgeous! :Q__ /loves space pics