This was interesting, because the overall tone of the book is to tip readers away from believing in UFOs, while attempting to acknowledge the validity of the question. This is unusual, because I think the approach tends to tip the other way--toward wanting readers to believe. (I can see a new Fox Mulder poster mixed with an Uncle Sam poster: I want you to want to believe!) And it is done with some interesting information, in a very compact book for readers in grades 2-4.
Most of all, I appreciated the fact that Portman was taking a historical approach to why the perennial topics are there and where they came from (how we started saying "flying saucer" or why the "weather balloon" explanation became a thing). The selected photos and art all felt consistent with the approach to the topic as a historical overview. There is no credited media researcher, so I wonder whether Portman was in charge of this himself, or if it was Kate Reynolds (designer) or Therese Shea (editor), or whether they just don't credit other staff at Gareth Stevens the way I'm seeing in books from other publishers.
The last page was really funny! It's a bar graph showing almost 8500 reports of UFOs in the past 4 years out of California. Over twice the number as the next states (New York, Florida, and Texas each have fewer than 4000 in the same time period.) Something about California!