So now I'm gonna tell you guys how you do this yourself.
Things you'll need:
2) light blue nailpolish
3) dark blue nailpolish
4) little piece of a sponge
First, you apply the dark blue nailpolish on your whole nails.
After it's dried, take a little piece of a sponge (cut it off), and apply the light blue nailpolish on it. Now, carefully apply it on the nails. You should get a galaxy-ish effect. Don't apply too much light blue polish!
When it's completely dried, use an invisible nailpolish and apply it on you nails. Now you're done! :)