Saturn held the title of outermost known planet for centuries, until better telescopes pushed the boundary of the solar system further out. This episode of the Cosmic Vistas series tracks that expansion, from William Herschel's discovery of Uranus by chance in 1781 to Neptune's arrival on the map after mathematicians predicted its position from gravitational wobbles before anyone actually saw it. The film leans on HD animation and archival telescope imagery to render both ice giants, their tilted magnetic fields, ring systems, and moons like Triton, and it revisits the Voyager 2 flybys that remain humanity's only close-up look at either world. Narration walks through what made these planets so hard to find and what the spacecraft data eventually revealed about their composition and weather. It is a straightforward planetary primer rather than a deep investigation, built for viewers who want a clear visual account of how the outer solar system was mapped.