"The planets were swirling around the sun, as usual," writes Underwood, when Neptune, peering through binoculars, spots another planet "circling another star, far, far, away!" The planets dispatch a "welcome to the galaxy" letter, but when they blithely address the recipient as "Exoplanet"--a planet outside the solar system--civility fails to launch. The planet insists that since it's circling "MY sun," the solar system planets are the real exoplanets; the squabble escalates, playground-style. Lacera's digital cartoons render planets as vivid characters: Jupiter, the blowhard leader, turns beet-red with rage, egged on by minion moons. A passing comet finally points out that who's "in" or "out" depends where one stands--or, as the planets sum up, "To us, you are an exoplanet. But to you, WE are the exoplanets. But no matter what anyone calls us, we are all round objects that travel around a star," delivering a contemporarily incisive message with a light touch. Ages 4--8. (Nov.)

Underwood and Lacera offer a light introduction to the concept of exoplanets in this jovial picture book starring our solar systems' eight planets and Pluto. Neptune (a teal orb perched in a pink pool tube) spots the faraway space objects first, and they decide to write a letter of introduction, explaining that they're calling the objects "exoplanets." The exoplanets are none too pleased, however; since our solar system's planets are so far away, they are the exoplanets, the reply explains. A snippy back-and-forth ensues until a comet helps the planets gain some perspective on point of view. The animated artwork nicely communicates tone (particularly from bossy Jupiter), and the dark color palette matches the space setting. Many kids in the target audience will recognize the comically escalating argument between the planets and exoplanets, and the comet's advice--though a touch didactic--might help little ones think about conflict. With a tidy combination of STEM content (back matter offers more information on exoplanets) and social-emotional learning, this approachable picture book can do double duty.

What's the difference between a planet and an exoplanet? Depends on your point of view. Lacera kits Mercury out with a winged helmet, Neptune with a pool toy, and the other major planets (plus Pluto, for, the author admits, sentimental reasons) with like regalia, plus faces, adding jocular notes to this planetary parable on proper perspective. The action begins when the planets spot a new one orbiting another sun and send it a welcoming letter. Alas, hardly has this developed into a regular correspondence than a sharp difference of opinion arises--both sides insisting that no, they're not the exoplanets, or, as Mars puts it: "Exoplanet SCHMECKSOPLANET! We're planets!" A passing comet breaks the stalemate by pointing out that Earth looks like a big planet to Mercury but a small one to Jupiter and that Mars is hot compared to Uranus but cold next to Venus, causing the planets to realize that "It all depends on how you look at things." One apologetic letter later, interstellar amity is restored. Underwood doesn't make the underlying point about the value of tolerating differences here on Earth explicit, but even younger audiences should get the memo…when they are not giggling at the sight of the planets playing poker while they wait or Jupiter's many smiling moons--or, more soberly, taking in the prodigious amount of space trash floating about. (This book was reviewed digitally.) A rollicking reminder to reserve judgment before traveling in another's orbit. (Picture book. 6-8) Copyright (c) Kirkus Reviews, used with permission.

PreS-Gr 2--Planets from our solar system send letters of love and friendship to an exoplanet, learning that different perspectives provide opportunities to grow. Bright digital art depicts anthropomorphized planets with fashion statements and personalities to match. Saturn's large eyeglasses mirror its rings, while Uranus wears a knitted cap as it's colder than other planets since it's farther from the sun. Jupiter, larger than all the others, dictates letters like a CEO. Underwood weaves in the definition of an exoplanet clearly, and the pun of signing XO as missives fly back and forth in "space express" rockets creates great read-aloud moments. The crux of the story, whether our solar system's planets are the exoplanets or the other planet is the exoplanet, causes disruption. A comet resolves it by pointing out how this is based on point-of-view. Comparisons of which planets are big or small, hot or cold, are discussed in relation to the sun, and this provides a teachable moment in differences and conflict resolution. A scientific note is included. VERDICT A delightful purchase that creates accessible paths to learning more.--Rachel Zuffa, Case H.S., Racine, WI