Astronomy (Ponderables)Here is the essential guide to astronomy, an authoritative reference book and timeline that traces how, over many centuries, great minds have figured out where we and our planet fit in the great expanse of the Universe. Since time immemorial, people have looked out into the night sky and brought back knowledge on how the Universe works. Gradually, astronomers have learned how it all beganin a Big Bangand are now faced with a variety of possible