<P>Once we thought the universe was filled with shining stars, dust, planets, and galaxies. We now know that more than 98 percent of all matter in the universe is dark. It emits absolutely nothing yet bends space and time; keeps stars speeding around galaxies; and determines the fate of the universe. </P><P>But dark matter is only part of the story. Scientists have recently discovered that the expansion of the universe is speeding up, driven by a mysterious commodity called dark energy. Depending on what dark matter and energy happen to be, our seemingly quiet universe could end its days in a Big Rip, tearing itself apart, or a Big Crunch, collapsing down to a universe the size of nothing, ready to be reincarnated in a Big Bang once again.</P><P>For the general reader and armchair astronomer alike, Iain Nicolson's fascinating account shows how our ideas about the nature and the content of the universe have developed. He highlights key discoveries, explains underlying concepts, and examines current thinking on dark matter and dark energy. He describes techniques that astronomers use to explore the remote recesses of the cosmos in their quest to understand its composition, evolution, and ultimate fate.</P>