Imagine the biggest thing you can think of--now imagine something bigger that hasn't even stopped growing. That is the universe. Our own galaxy, the Milky Way, though enormous, is a tiny speck among the 100 billion galaxies containing nebulas, planets, "space pods," billions of stars, and black holes that fill the cosmos. New stars, planets, and galaxies continue to form as the universe expands. Award-winning science writer Seymour Simon...