Living in a world as vast as Earth, it can be easy to forget that this blue planet is actually a tiny speck within a massive universe filled with planets, moons, stars, asteroids, comets, dark matter...and maybe even alien life. Read about Earth's place in the Milky Way and the larger universe and how humans are learning about the endless frontier of space--and whether we are alone.

1. Earth (Planet) -- Juvenile literature.; 2. Solar system -- Juvenile literature.; 3. Outer space -- Juvenile literature.;