If you were to give a boy a book about space travel and a trip to the moon, I'm guessing that a novel written in 1865 wouldn't be the first one you'd come up with.  From the Earth to the Moon by Jules Verne is the book you may have forgotten, about a gun club trying to build the biggest gun ever, one big enough to shoot the moon!

Seriously.  As in, they are actually trying to get a projectile to the moon.  With a giant gun.

Shortly after the American Civil War, a gun club decides that it would be interesting to see if a cannon could be built that would shoot a projectile to the moon.  Barbicane, the president of the gun club, makes a series of bets with his nemesis that make the construction of the cannon a matter of pride. things get tense, and with money and honour on the line, the consider a radical idea: riding in the projectile and going to the moon themselves.

Mr. Verne goes to great lengths to describe the process of building such a ridiculous thing, from picking the best location and materials to the feasibility of a human traveling in the projectile and surviving, but the book is fairly light, even with all the engineering talk.  The characters are broadly drawn and the situations are reasonably amusing.  Despite all that, the moon landing that seems like a distant memory now (or, my generation and younger, outside of our lifetimes entirely) was over a hundred years away when this book was written, but the proposals and predictions on how to get there are remarkable accurate.  Verne guessed the location, the cost and even the approximate weight of the venture, and even though his solutions to getting to the moon aren't exactly feasible, a lot of it turned out true.

Many of Jules Verne's books are still quite readable, even after 150 years, but it really all depends on the translation (newsflash! He was French).  These are good for all ages, but I think younger teen boys might appreciate these most.  I might have been 12 when I first read it.