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Steven Weinberg's "The First Three Minutes" might be the best SECOND book to read on Cosmology. Because "The First Three Minutes" concentrates on the very early development of the Universe and does not provide much historical development to what lead up to the great discoveries of the Twentieth Century, a reader with little or no knowledge of Cosmology might find it heavy going.
For instance Weinberg starts off his description of "black body radiation" with "By the 1890s it had become known that the properties of radiation in a state of thermal equilibrium with matter depend only on the temperature. To be more specific, the amount of energy per unit volume in such radiation within any given range of wavelengths is given by a universal formula, involving only the wavelength and the temperature". All of that is absolutely correct of course, but it is a bit much to work through. It seems that a brilliant educator such as Richard Feynman would have thought up a description equally accurate but more intuitive.