A new video, above, breaks down all the things you can expect from the DLC, which will cost $9.99. They include boosting the number of anomalies in the game by 50%, lots of new systems to explore, and three new leviathans. Two of those leviathans will function similarly to the space dragons from previous expansions, but the third will be "quite different".
The biggest addition is a new cluster of stars called the L-Cluster, which is separated from the rest of the galaxy. Paradox isn't saying much about it, other than you have to find and fix malfunctioning L-Gates in order to reach it.
Paradox will also release the game's free 2.1 Niven update alongside Distant Stars. Niven, which I wrote about here, overhauls anomalies and the way you travel between stars and systems.