Kathryn D. Sullivan, also known as “The Most Vertical Person in the World”, has spanned the greatest distance that any Earthling has travelled, from the deepest ocean to the altitudes of three space-shuttle missions.

Among the first women in the US space programme – and the first American woman to “walk in space” — she is also an oceanographer, global explorer, pilot, 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, USA, 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; A Tale of Rescue, illustrated by Stan Fellows; and four volumes of haiku.

Although his imagination has soared in many directions and genres, the 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 Appalachia foothills of Ohio, USA, where he also works as a painter, sculptor, printmaker, and companion animal to a cattle dog named Chant.