The March freebie from the University of Chicago is
How We See the Sky: A Naked-Eye Tour of Day and Night by Thomas Hockey.
How We See the Sky gives us back our knowledge of the sky, offering a fascinating overview of what can be seen there without the aid of a telescope. Thomas Hockey begins by scanning the horizon, explaining how the visible universe rotates through this horizon as night turns to day and season to season. Subsequent chapters explore the sun’s and moon’s respective motions through the celestial globe, as well as the appearance of solstices, eclipses, and planets, and how these are accounted for in different kinds of calendars.