In less than a century, the accepted picture of the universe transformed from a stagnant place, composed entirely of our own Milky Way galaxy, to a realm inhabited by billions of individual galaxies, hurtling away from one another. We must thank, in part, Edwin P. Hubble, one of the greatest observational astronomers of the 20th century. In 1936, Hubble described his principal observations and conclusions in The Realm of the Nebulae, which quickly became a classic work. Two new introductory pieces, by Robert P. Kirshner and Sean M. Carroll, explain advances since Hubble’s time and his work’s foundational importance.

"Meaningful, historically accurate, and thoroughly delightful reading."—Gail O. Clark, Astronomy

"This enduring work is the closest we can get to Edwin Hubble’s personal thoughts as he broke open the boundaries of the universe in the early twentieth century. In this compelling summary of his historic observations of myriad galaxies swiftly moving outward in space-time, we see both his awe—and his doubts—over the new and surprising cosmos he had revealed. A true classic of scientific literature."—Marcia Bartusiak, MIT, author of The Day We Found the Universe

-- Marcia Bartusiak

Edwin Hubble spent most of his illustrious career at the Mount Wilson Observatory, in Pasadena, California. Robert P. Kirshner is Clowes Professor of Science at Harvard University. Sean M. Carroll is Senior Research Associate at the California Institute of Technology.