Here is a vector of rainbow galaxy background, include a eps file.
Name: Free Rainbow Galaxy Vector Background
Homepage: Gwebstock
License: Creative Commons Attribution-Share Alike 3.0 Unported
File Type: EPS
This image is a scalable vector illustration and can be scaled to any size without loss of resolution. This image will download as a .eps or ai file. You will need a vector editor to use this file (such as Adobe Illustrator or CorelDRAW).