Alice and her friend Zack look out on the world from her tree house and notice that the sun is setting earlier. Over the course of a year, they see all kinds of changes in their backyards: falling leaves and migrating birds in autumn; drifts of snow and animal tracks in winter; sprouting crocuses and peeping frogs in spring; and hot days and flashing fireflies in summer. 

But what really fascinates Alice and Zack are the reasons for the seasons. They learn that the earth's orbit around the sun, combined with the tilt of the earth's axis, creates all the changes they observe. The earth is like a giant spaceship, carrying us through the seasons.

Kathleen Weidner Zoehfeld packs her story with sensory details, funny observations, and solid science. And Priscilla Lamont's charming illustrations and clever charts make a complicated concept completely clear for budding scientists. Together they answer that all-important question: Why?

From the dust jacket