Are There Other Galaxies?

"Are there other galaxies out there? How do we know that they exist? Can we expect an alien invasion? In this fascinating book, readers will learn about black holes, gigantic telescopes, and space exploration. Brilliant photographs are paired with diagrams to allow readers to visualize the information, as clear and fact-filled text helps explain concepts in an age-appropriate way. Sidebars enhance each topic with useful facts and information, and fun science projects allow readers to learn through hands-on experiments"--Provided by the publisher.