At the beginning of this cosmic journey across space and time, Dr. Carl Sagan takes us to the edge of the universe aboard a spaceship of the imagination. Through beautiful special effects, we witness quasars, exploding galaxies, star clusters, supernovas and pulsars.

Dr. Sagan's cosmic calendar makes the history of the universe understandable and frames the origin of the Earth and the evolution of life. We see the evolutionary process unfold, from microbes to humans.

This episode is a historical re-creation of the life of Johannes Kepler, the last scientific astrologer, the first modern astronomer and the author of the first science fiction novel.

A descent through the hellish atmosphere of Venus to explore its broiling surface serves as a warning to our world about the possible consequences of the increasing greenhouse effect.

Is there life on Mars? Dr. Sagan takes viewers on a tour of the red planet first through the eyes of science fiction authors, and then through the unblinking eyes of two Viking spacecrafts that have sent thousands of pictures of the stunning Martian landscape back to Earth since 1976. Though based on older Mars missions, Sagan's analysis still holds true.

Dr. Sagan compares the exhilaration of 17th-century Dutch explorers who ventured in sailing ships halfway around our planet in their quest for wealth and knowledge to an inside view of the excitement around Voyager's expeditions to Jupiter and Saturn.

Humans once thought the stars were campfires in the sky and the Milky Way "the backbone of night."

A voyage to see how star patterns change over millions of years is followed by a journey to the planets of other stars, and a look at the possibility of time travel.

Using computer animation and amazing astronomical art, Dr. Sagan shows how stars are born, live, die and sometimes collapse to form neutron stars or black holes.

Dr. Sagan leads us on some awesome trips — to a time when galaxies were beginning to form, to India to explore the infinite cycles of Hindu cosmology, and to show how humans of this century discovered the expanding universe and its origin in the big bang.

The brain is the focus of this fascinating portion of our journey as Dr. Sagan examines another of the intelligent creatures with whom we share the planet Earth — whales.

Are there alien intelligences? How could we communicate with them? What about UFOs? The answers to these questions take us to Egypt to decode ancient hieroglyphics, to the largest radio telescope on Earth and, in the Spaceship of the Imagination, to visit other civilizations in space.

Through the use of special effects we retrace the 15-billion-year journey from the big bang to the present. We also hear the tragic story of the martyrdom of Hypatia, the woman scientist of ancient Alexandria.