Long ago, from the fires of our Sun's birth, twin planets emerged: Venus and Earth. Nature draped one world in the greens and blues of life, while enveloping the other in acid clouds, high heat, and volcanic flows. Why did Venus take such a disastrous turn and Earth developed a vibrant biosphere?

Massive solar eruptions take aim at our high-tech society. 93 million miles away... an angry sun vents its rage. Dark regions, called sunspots, appeared unexpectedly on its surface... a sign of rising tension within. It had been three and a half years since the sun last erupted in fury...at the peak of an 11-year cycle of solar flare-ups.

Did Mars long ago develop far enough for life to arise? If so, does anything still live somewhere underground? The search for answers has revealed the forces that long ago doomed the Red Planet.

From the Cassini spacecraft comes one of the greatest photographic collections. Scientists are using it to uncover a trail of clues pointing to the energy sources and complex chemistry needed to spawn life.

Join a small team of rocket designers as they open a window into the future of space travel.

The two Voyager spacecraft are part of an ancient quest to push beyond our boundaries... to see what lies beyond the horizon. Now tens of billions of kilometers from Earth, two spacecraft are streaking out into the void. What will we learn about the Galaxy, the Universe, and ourselves from Voyager's epic Journey to the stars?