Cameras on phones just aren't designed for the narrow field of view that much of astrophotography uses. The thing to look up is "wide field astrophotography" -

Cameras on phones just aren't designed for the narrow field of view that much of astrophotography uses. The thing to look up is "wide field astrophotography" - but even then, you get into issues. While it's a little dated (digital has come a long way), if you are interested in it with a "real" camera... hunt up a copy of Heavenly Bodies: The Photographer's Guide to Astrophotography by Bert P Krages.