Kathryn D. Sullivan, dubbed “the most vertical woman in the world” by coauthor Michael J. Rosen, has spanned the greatest vertical distance that any earthling has traveled, from the deepest ocean to the altitudes of three space shuttle missions. Among the first women in the US space program and the first American woman to conduct a spacewalk, she is also an oceanographer, global explorer, and pilot, as well as the author of Handprints on Hubble and the host of the podcast Kathy Sullivan Explores. For several years, she served as under secretary of commerce for the National Oceanic and Atmospheric Administration (NOAA). She lives in Ohio with a pair of Havanese pooches.

Michael J. Rosen is the author of some 150 books for readers of all ages, including A Ben of All Trades: The Most Inventive Boyhood of Benjamin Franklin, illustrated by Matt Tavares; The Tale of Rescue, illustrated by Stan Fellows; and four volumes of haiku. Although his imagination has soared in many directions and genres, one he’s never considered is up: a step stool is his maximum height, and a sheet of black construction paper on the floor makes him dizzy. Michael J. Rosen lives in the Appalachian foothills of Ohio, where he also works as a painter, sculptor, and printmaker and as the companion animal to a cattle dog named Chant.