Forged from the same primordial dust, the terrestrial planets – Mercury, Venus, Earth, and Mars – share a common origin, yet their histories diverge dramatically. What powerful forces have sculpted such disparate destinies?

Professor Brian Cox, in his ongoing exploration of our solar system, reveals a startling history: evidence suggests that the system once harbored not a single, but two planets bathed in blue light.

Brian Cox turns his attention to the solar system's largest member, Jupiter. The planet’s immense scale grants it a formidable influence, one it has wielded to shape the movements of its celestial neighbors.

Professor Brian Cox recounts the story of Saturn's formation. Initially a peculiar world composed of rock and ice, Saturn gradually evolved into a gas giant, initially devoid of rings and bearing a resemblance to its neighbor, Jupiter.

The concluding episode finds Professor Brian Cox venturing to the solar system's farthest reaches, a realm inhabited by the enigmatic planets themselves.