Now go outside and look at the sky.
History of Science
I'm currently reading Bill Bryson's new book "A Short History of Nearly Everything", and as the title suggests, it is an all-encompassing tour de force across all the major sciences, their history and personalities.
I'm thoroughly enjoying this book, it is not just a great (but light) refresher in the natural sciences, it offers many wonderful and funny biographies of all the most eclectic and productive scientists of the 18th and 19th century.
Unputdownable, as they say...