The Invisible Leader

How the Earth Works takes you on an astonishing journey through time and space. In 48 half-hour lectures, you will look at what went into making our planet—from the big bang, to the formation of the solar system, to the subsequent evolution of Earth. You will travel to the center of our planet and out again, charting the geologic forces that churn beneath our feet to push the continents and seafloor around like so much froth on the surface of a pot of soup.

The fourth season of the American science fiction television series The X-Files commenced airing on the Fox network in the United States on October 4, 1996, concluding on the same channel on May 18, 1997, and contained 24 episodes. Following the filming and airing of the season, production began on The X-Files feature film, which was released in 1998 following the show's fifth season.

The fourth season of the series focused heavily on FBI federal agents Fox Mulder's (David Duchovny) and his partner Dana Scully's (Gillian Anderson) investigation of an alien conspiracy, which is protected by the mysterious Syndicate. Midway through the season, Scully is diagnosed with terminal cancer, a result of her previous abduction, and Mulder begins to lose his faith in the idea of extraterrestrials. The season ends on a cliffhanger, with the purported suicide of Mulder.