Rada and Jonny have always lived on a little world far out in space where their father works on spaceships. They are the only children on the little world; they know about wearing space suits, about the black sky, and about needing air to breathe.

Spaceships come to the little world where the men who work there make sure everything is right before the ships travel to Earth or to other planets. When the space travelers see Rada and Jonny, they say, “Think of that! Children live here.” One of the space travelers tells the children how Earth is different from their little world.

On the little world, Rada and Jonny live underground with their parents. Since their world is so small, there is only a little gravity, so the children can bounce and milk can float in bubbles. Their parents tell the children more about what it is like on Earth.

When Rada and Jonny learn they are going to Earth, they have to exercise to get their muscles strong for Earth’s stronger gravity. Soon the ship that would take them to Earth came to the little world.

When the children reach Earth, they make many discoveries. And they get to try something they have never done before. What is the best new thing?

This fact-based picture book story, Isaac Asimov’s first science fiction book for very young readers, introduces science concepts of space and gravity. Young readers discover the difference between living on Earth and living on a little world out in space. Rada and Jonny help them learn about spacesuits and the pull of gravity, about what it might be like to travel on a spaceship.

The colorful illustrations accompanying the narrative are charming and instructive. Parents and young readers will enjoy sharing this delightful story and discovering what Rada and Jonny proclaim to be the best new thing.

Highly recommended. ( )