Books in the Twinkle Twinkle Little Star series

When a young stargazer sees a star, he and the star form an unlikely friendship where the two exchange letters about their different worlds. While Thomas tells the star about the modern world of Astronomy, his star friend, Sax, tells him about how important the stars and planets use to be to the world. Sax describes himself much like a clock in the sky, foretelling of rivers rising and falling, and even when to expect the next king. Sax, all his family, and his friends were once employed, full time, helping the people of earth prepare for planting, harvesting, and even giving inspiration for building new technology.