NOVA: The Planets

The rocky planets were born of similar material around the same time. Yet only one of them supports life. Were Earth's neighbors always so extreme and is there somewhere else in the solar system life might flourish?

Mars was once a blue water-world with active volcanoes. But when its magnetic field and protective atmosphere faded, it became the frozen desert planet we know today. With so many necessary elements in place, did life ever form on Mars?

Jupiter's gravitational force made it a wrecking ball when it barreled through the early solar system. But it also shaped life on Earth, delivering comets laden with water-and perhaps even the fateful asteroid that wiped out the dinosaurs.

NASA's Cassini explores Saturn for 13 years, looping through its icy rings and its moons. The probe captures stunning ring-moon interactions, but when it finds the ingredients for life on the moon Enceladus, a bittersweet decision is made.

In the far reaches of the solar system, Uranus and Neptune dazzle with unexpected rings, supersonic winds, and dozens of moons. And NASA's New Horizons gets a stunning up-close view of Pluto before venturing deep into the Kuiper Belt.