Image: Da Capo Press

Hollow Earth: The Long and Curious History of Imagining Strange Lands, Fantastical Creatures, Advanced Civilizations, and Marvelous Machines Below the Earth’s Surface

By David Standish

De Capo Press, US $25, ISBN 978-0-306-81737-3

A fascinating history of an idea that just refused to die, Hollow Earth, describes how, for hundreds of years, people believed that an inhabited subterranean world existed beneath our feet. In the concept’s most extreme form, this world was not just a series of caverns, but had it’s own light, air, oceans, and continents teeming with strange creatures, all located on the inside of the thin shell of the Earth’s crust. But what’s really surprising about Standish’s book is how seriously the idea of a hollow Earth was taken at one time, and how it wasn’t such a crackpot idea when first mooted.

The first serious hollow Earth theory was proposed by no less than Sir Edmund Halley (best known for predicting the motion of the comet now named after him). Noting that Earth’s magnetic poles move around, and figuring that some internal motion was responsible, he postulated that the Earth wasn’t a single solid sphere, but contained a number of nested hollow spheres. In fact, this wasn’t a bad guess, and our current understanding of the Earth’s structure is not a million miles away from Halley’s idea—the wandering motion of the Earth’s magnetic field is due to its origin in circulating electric currents in the molten outer core which separates the inner core from the planet’s rocky mantle.

However, things started to get a bit crazy in the 19th century, with people raising money for expeditions to the hollow Earth, which they believed could be reached through vast holes where the Earth’s poles should be. But when more and more polar explorers failed to report any evidence of giant holes, the Hollow Earth idea slid into the realm of fantasy and science fiction—almost. As late as 1961, a small colony of so-called Koreshans lived in Estero, Fla., who believed that not only was the Earth hollow, but that we are actually living on the inside, with the sun and stars residing on the surface of another globe rotating above us. As a well-told story about a bizarre idea that still lurks on the edges of popular imagination, and the people who believed in it, Hollow Earth is a great read.

Kids' Corner

Kids to Space: A Space Traveler’s Guide

By Lonnie Jones Schorer

Apogee Books, US $30, ISBN 978-1894959-42-1

Image: Apogee Books

Aimed at younger readers, Kids to Space should also be very useful to educators and parents looking to interest kids in astronomy and space travel. The book is filled with answers to questions that children and teenagers often ask about space travel, including things like “What are the chances of getting marooned on a planet?,” “What is inside a black hole?” and “How big is an airlock?” An accompanying CD contains slideshows of space-related art by children.

The book is the result of a project sponsored by Global Space Travelers, an organization founded by Apollo 11 moonwalker, Buzz Aldrin. 6000 students ranging from 3 to 19 in schools around the U.S. asked questions of 90 experts, which included former astronauts, leading space scientists, and even space entrepreneurs like Richard Branson. Although the book is very U.S. centric—many of the questions concern the space shuttle—the quality of the answers is high, written in a way that should be understandable to most children without being either boring or patronizing. If you have budding astronauts in the house, this might just be the book for them.