Neptune Book Mistake

My daughters picked out a kid's book on Neptune the other day from the library.  One evening before bed I sat down to read it to them and ran across a mistake.  It was most likely a typo.  Let's see if you can find it.

Find it?  Look closely!  On the left page it says that Voyager 2 launched in 1977.  This is correct.  However, on the right page it says that Voyager 2 launched in 1989.  This is incorrect.  Voyager 2 flew by Neptune in 1989!  It's still a good book, but the Ph.D. in astrophysics leaves me picky when it comes to typos such as this.  :-)