Forty years ago, world-renowned University of Iowa space physicist Louis A. Frank found evidence that would lead to a startling discovery: Every minute several huge “snowballs” break up as they approach the Earth and deposit a large cloud of water vapor in our upper atmosphere. His conclusion, based on data from the Dynamic Explorer 1 spacecraft acquired at the limits of detection, created a storm of controversy among scientists. This is the story that was told in the first edition of this book, The Big Splash, published in 1990. But the story does not end there. Less than a decade later, Frank’s discovery of these previously undetected small comets was confirmed when images were received from cameras aboard a different spacecraft named Polar. The news of this “vindication” of Frank’s provocative theory in 1997 made the front pages of several large metropolitan newspapers, including The New York Times, The Philadelphia Inquirer, and The Washington Post. Cosmic Rain: The Controversial Discovery of Small Comets—a large format, full color, greatly expanded edition of The Big Splash—tells this never-before-told follow-up, in Frank’s own words, of the confirmation of the existence of small comets and the harsh criticism he faced from colleagues for upsetting so many scientific applecarts in the process.