The universe has sprung many remarkable surprises on us in the past few years. Scores of planets have been detected around other stars. Vast amounts of ice and evidence for recent liquid water have been found on Mars. Brown dwarfs, medium- sized black holes, giant Centaurs, ultra-luminous clusters, microquasars, and magnetars have been added to an already extraordinary cosmic menagerie. Dark energy has joined dark matter as a likely chief ingredient of the universe, which, against all expectations, seems to be gathering pace in its headlong outward rush. We have seen the surface of the Sun, the center of our galaxy, and the environs of dying stars in unprecedented, awe-inspiring detail. We have begun to make out the great filaments of galaxy clusters and the gaping voids that are the largest of cosmic structures.

We are lucky to find ourselves in a world of such wonders at a time when they are being revealed by powerful new instruments—the enhanced Hubble Space Telescope, the Very Large Telescope, the Chandra X-ray Observatory, and others. Yet the breakthroughs are coming so thick and fast that it is hard, even for professional astronomers let alone the interested layperson, to keep track of them. By including the latest results and conjectures alongside well-established theory and facts, and by extensive cross-referencing, this website offers a way for everyone, from the nonspecialist to the seasoned researcher, to gain a better grasp of the modern universe. And grasp it we should because we are all part of this astonishing creation—our very bodies fashioned of atoms that were made in- side giant stars long ago. Bring only your imagination and the courage needed to gaze up and out across 15 billion light-years!