Thursdays are drinking days, a number of us gathering at Cunneen's Tavern regularly. The Thursday before last a science-inclined friend came by and I mentioned that I'd just read Asimov's book on comets. This led to a discussion wherein he mentioned that all of Earth's water may have come from the hypothetical Oort Cloud. I expressed some doubt at this proposition but decided to pursue the idea by checking out what the famous panspermian, Fred Hoyle, had to say in this book that's been laying about for years.
Indeed, Hoyle makes a case for my friend's claim, may in fact have been a source of it. Further, Hoyle suggests that life may have been kick started off-planet, complex organic molecules becoming increasingly evident elsewhere.
The thrust of Hoyle's book is that the sources of life are to be looked for from a cosmic, not a terrestrial, perspective. There is strong evidence that the conditions for life exist throughout the universe, the creation of such conditions being common in the evolution of stars.
I'm not much of a physical science person and this book is written on the level of a Scientific American article on the subject. I found parts difficult, but a decent high school student should have no problem. Note, however, that the author is English and uses Kelvin and decimal scales of measurement.