Mastodawn

I'm writing a series of novels tied to a tabletop RPG (#SublightUniverse).

It is set in space, but the world doesn't allow for any effect to be faster than light. Most of civilization has shifted to living on space stations scattered around the Solar System.

So I've come up with a calendar system that people in space would use. The trick is to just live with a 364 day year, and have 13 months of 28 days.