- Add-on releases on Celestia Forums
In this forum, you will find many add-ons created by the Celestia community.
- Celestia Motherlode
The Celestia Motherlode was the central repository for Celestia add-ons.
- Selden's Catalogs of Objects for Celestia
- Introduction to Creating Celestia Add-Ons
Selden Ball has created a very helpful introduction to creating add-ons for Celestia. If some of your favorite astronomical objects are missing from Celestia, or if you want to create an entirely ficitious planetary system, then you'll be interested in reading this add-on introduction.