Beginning with the origins of the universe in the Big Bang, Sagan describes the formation of different types of galaxies and anomalies such as galactic collisions and quasars. The episodes moves further into ideas about the structure of the Universe, such as different dimensions (in the imaginary Flatland and four-dimensional hypercubes), an infinite vs. a finite universe, and the idea of an oscillating Universe (similar to that in Hindu cosmology). The search into other ideas such as dark matter and the multiverse is shown, using tools such as the Very Large Array in New Mexico. Cosmos Update shows new information about the odd, irregular surfaces of galaxies and the Milky Way perhaps being a barred spiral galaxy

Questions are raised about the search for intelligent life beyond the Earth, with UFOs and other close encounters refuted in favor of communications through SETI and radio telescope such as the Arecibo Observatory. The probability of technically advanced civilizations existing elsewhere in the Milky Way is interpreted using the Drake equation and a future hypothetical Encyclopedia Galactica is discussed as a repository of information about other worlds in the galaxy. The Cosmos Update notes that there have been fewer sightings of UFOs and more stories of abductions, while mentioning the META scanning the skies for signals.

We can't compare anything on earth to the biggest things known in space. The Cosmic Web may connect objects in the universe with threads of Dark Matter. The Lyman-alpha blob is a bubble like structure containing countless galaxies--perhaps the biggest object in the entire universe. Regions of radio-emitting gas called "radio lobes" could be even bigger. Then there are super galaxy clusters which are hundreds of galaxies merged together due to cosmic collisions. Discover which is the largest planet, star, star cluster, constellation, black hole, volcano, galaxy, explosions, moon, storm, impact crater and "void" in space.

The universe began with a massive expansion, billions and billions of years ago, and it continues to expand with every passing second. The idea that the universe, and man's very existence, began with a "Big Bang" is no longer a topic of debate among most scientists--it is essentially taken as fact.

From stars, galaxies and moons to subatomic particles, black holes and invisible phenomena, discover the most bizarre, mysterious and exotic things in our universe

Some of the world's leading physicists believe they have found startling new evidence showing the existence of universes other than our own. One possibility is that the universe is so vast that an exact replica of our solar system, our planet and ourselves exists many times over. These Doppelganger Universes exist within our own Universe; in what scientist now call "The Multiverse." If proof is found it will change our lives, our minds, our planet, our science and our universe.