An hourly guide that tracks twenty-four stars, stellar clusters, and constellations across the sky to reveal their luminous lives and lore.

Over the course of a day, the constellations slowly shift, rising in the east and setting in the west, all due to the Earth’s rotation. A full turn of the celestial sphere, that bowl above us where the stars seemingly appear fixed to the surface, is completed once every twenty-four hours. In fact, the stars first defined the twenty-four-hour day, and one star, our sun, rules the circadian rhythms of all life on our planet. This short book sweeps through the celestial sphere hour by hour, introducing a remarkable cast of stellar characters with each chapter. Celebrated science writer Marcia Bartusiak and mathematician Stephen Lowe blend practical astronomy with fascinating history to share unique cosmological stories.  

This husband and wife team explain that observers have long split the sky into twenty-four hours of “right ascension”—a celestial equivalent of longitude and a universal scheme for locating cosmological objects. Each chapter of Star Day presents a single right ascension hour, from the stellar death of Supernova 1885A (0th Hour)—an explosion that helped reveal the size of the universe—to Scheat (23rd Hour), an aging red giant. Twice the mass of the Sun and some 1,500 times as bright, Scheat sometimes guides amateur astronomers to distant galaxies. In between, we learn about humans’ pole star, Polaris (2nd hour), and meet the supermassive black hole at the center of our Milky Way galaxy (17th hour). By the end of our star day, we will appreciate both our own stellar origins and the fragile and deep connections between human civilizations and the ever-changing heavens. Star Day reminds us that wonder and discovery are easily available, all for the simple price of looking up.

For each chapter, artist Matthew Green has depicted these stellar scenes with entrancing pen-and-ink drawings. Working together to narrate and illustrate these stars, Bartusiak, Lowe, and Green have created an engaging read that is a perfect way to spend an hour or two—and a true gift to both seasoned skywatchers and curious beginners.