I'm a fully-grown adult and learned a lot of new things from this children's book. Every child learns about the planets in our solar system and the characteristics of each. But this is something that's most likely new to them. Or, if they've learned it, they don't remember it with the same voracity of the facts about Mars or Venus.
Exoplanets. New ones are being discovered every day. This is ongoing science, not something discovered many years ago. And the information is presented in a gorgeous package. The imagery is incredible.
Final Verdict: A beautiful and well-done way to get children interested in this area of science.