(4) K-3 Illustrated by Diane Kidd. The history of Pluto, from discovery to inclusion as a planet to eventual reclassification as a dwarf planet (the titular secret), is described in a back-and-forth between scientists and an anthropomorphized Pluto. The fanciful premise, cartoonlike illustrations, and goofy dialogue, though amusing, may distract from the sound information; extensive back matter reinforces the science. Reading list. Bib., glos., ind.

Reviewer: Devon Johnson