Essentially this vast 1:1 scale simulation of our galaxy is based on real scientific principles, and current scientific data and theories. It includes around 400 billion star systems, modelled on actual galactic charts.
To date, E:D players have traversed 201 million of these 400 billion star systems, which equates to around 0.05%
Constellation Check: When you get to Sol, open the galaxy map and search for and target Mintaka. When you exit the galaxy map take a good look at the shape around the star you just selected, and you should see Orion. Then do the same with Alioth, and you should see the big dipper.
Further, for intrepid explorers the ‘First Footfall’ achievement will soon be available in the upcoming Odyssey expansion that will unlock “billions” of traversable worlds on 19 May 2021. Meanwhile, see some screens above and linked from the ‘Odyssey update’s new tenuous atmospheric planets.’