From Starbounder - Starbound Wiki
Version 1.0 was Starbound's feature complete release, which was deployed on July 22nd, 2016. It ended the public beta and early access for the game, having assembled the game's core features and progression.
It was announced and changes were detailed on the developer blog shortly after release.
For a full breakdown of changes specific to this update see the changelog for Cheerful Giraffe.