As I worked through the shelves, I developed these cutoff dates for planet-specific books. Books older than these should be closely investigated to see if they still hold up. This list of dates would be different (more recent) for middle- and high-school level books, which should cover the topics in more detail so would need to be more up-to-date, particularly for Mars, asteroids, and Saturn. This list only applies to the planetary books in the Science section (Dewey 520s), not the space exploration books in the Engineering section (Dewey 629.4), which I have not gotten to yet.

Mercury: 2008 (before the first MESSENGER flyby)

Venus: 1993 (sigh. There's not been a lot since Magellan that you'd put into a young child's book)

Moon: Depends on the focus of the book.

Mars: 2005 (after Mars Exploration Rovers landed, but 2008 would capture Phoenix ice and amazing Mars Reconnaissance Orbiter images)

Asteroids: 2000 (which gets you Ida, Gaspra, and Eros, as well as the Shoemaker-Levy 9 impact)

Jupiter: 2001 (which gets you most of the Galileo mission as well as better global Cassini images)

Saturn: 2005 (to capture the initial results from Cassini)

Uranus: 1987 (sigh. Books published after 2005 have the chance to include the news that Uranus is not as boring as it was when Voyager passed by, as witnessed by Earth-based telescopes.)

Neptune: 1990 (again, sigh. Books published after 2005 would hopefully include changes observed since Voyager, including the fact that the "dark spot" is not permanent.)

Comets: Depends on the focus of the book. Of the five comet books that were on the shelf, only one showed a photo taken by a spacecraft, and that was a Giotto image of Halley. All other pictures were Earth-based photos of pretty comet comas and tails. Books published after 2006 could have featured Stardust and Deep Impact images of comet nuclei, but the two on this particular library shelf didn't.

General solar system: Books for this age group after 2000 are usually okay; after 2006 is better because they should have a more detailed picture of the diversity of small bodies in the solar system.

Pluto presented an interesting challenge, because New Horizons will change everything, but those changes haven't propagated to books yet, of course. In the end, I eliminated none of the Pluto books on the shelf; I deferred that for a year. I also didn't eliminate any books just because they called Pluto a planet, because I don't think there's any harm at all in letting kids notice that its status changed over time. It was interesting to see how books published in different years handled Pluto's planetary status. Some from the early 2000s had sidebars talking about differing opinions on its status. More recent ones that included Pluto generally also included Ceres and Eris in solar system diagrams. I think it would be a fun library project for a strong elementary-school reader to take a stack of solar system books off the shelf, learn how to look at the publication date, sort them by date, and then read what each says about Pluto.

When I was done, I had eliminated nearly all of the library's books specifically about Mercury and Mars, and I wasn't particularly happy with the comets section for its lack of spacecraft images. So here is a list of books that I will recommend that the school librarian investigate for purchase, based on my past book reviews. Many of them are actually series of books that cover the entire solar system, so if your library is missing a different subset of planets, you can probably find replacements here.

General solar system books:

Book series:

I have just gone through Amazon to find new nonfiction space series and have sent out a pile of emails requesting review copies of brand-new space books. I usually post my reviews in November; stay tuned!