With the DVD release (on five discs) of this, the complete second season of The Universe, the History Channel has now devoted a combined total of more than 25 hours, not including bonus material, to its documentary study of that combination of time, space, and matter that we call our universe. That痴 a lot. But then you consider the mind-boggling age and size of the universe itself: 13.7 billion years old, and big beyond our comprehension; infinite, in fact, and expanding rapidly. By those measures, it痴 apparent that this fascinating series could probably air for longer than The Simpsons and Gunsmoke (the two longest running shows in TV history) put together and still not run out of things to talk about.

The 18 episodes from Season Two cover an appropriately wide range of topics, from "Cosmic Holes" to "Cosmic Collisions," from supernovas to gravity. There are episodes about the weather in space, the largest objects in space (hint: they池e really, really big, like the so-called "cosmic web" of galaxies, which is a hundred million billion times bigger than Earth), and traveling to and colonizing space. The amount of information and data provided is enormous. Jargon abounds, including terms like "lunar transient phenomena," "pulsar planets," "hot Jupiters," "dark matter" and "dark energy," "collisional families," the "heavy bombardment period," and many, many more. And the numbers are mind-boggling: for instance, it痴 estimated that the impact of the asteroid that landed on the Yucatan Peninsula some 65 million years ago, wiping out the dinosaurs, was equal to that of dropping a Hiroshima-sized atomic bomb every second for 140 years! Still, some may find the episodes that involve informed speculation more interesting than those that deal in facts. We know that the Moon affects ocean tides, but does it also have an effect on human behavior? If the Big Bang was the beginning of the universe, what came before it? Instead of using rockets to go to space, can scientists actually build a "space elevator" that will reach from an orbiting satellite some 60 thousand miles down to Earth? All of this is delivered by way of very convincing computer-generated imagery and other effects, along with dozens of interviews with astronomers and other experts, photos, film footage, and so on. Best of all, while it can get a bit dense, technically speaking, by and large The Universe will be readily accessible to most viewers. --Sam Graham