2 books · Ages 4–9 · Poetry, Chapter Books
Meet the Universe is a 2-book series for ages 4–9 by Eve M. Vavagiakis. Each book stands alone — start anywhere.
Start anywhere — each book stands alone.
That said, I'm a Black Hole and I'm a Neutrino: Tiny Particles in a Big Universe are great first picks.
No particular order needed — browse and pick what catches your eye.