The title of Ava DuVernay's extraordinary and galvanizing documentary refers to the 13th Amendment to the Constitution, which reads 'Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States.' The progression from that second qualifying clause to the horrors of mass criminalization and the sprawling American prison industry is laid out by DuVernay with bracing lucidity. With a potent mixture of archival footage and testimony from a dazzling array of activists, politicians, historians, and formerly incarcerated women and men, DuVernay creates a work of grand historical synthesis.

From a 2,400-year-old corpse in remarkable condition to how shrunken heads are made, these 15 ancient secrets will have you completely riveted. The Vesuvius eruption may have been a gradual process. It took a storm to lift the cover on this ancient Roman city. The people of Pompeii often resorted to vigilante justice. How the wealthy of Pompeii protected their valuables? Was this pre-Viking gathering a prelude to a massacre? The valuable commodity behind King Solomon's wealth. This valuable Viking grave is missing something important. Is this where humanity decided to settle down? This mysterious stone structure is older than Stonehenge. This 2,400 year old corpse is in remarkable condition. Here's exactly how shrunken heads are made. DNA analysis reveals troubling news about shrunken heads. This mass grave discovery could alter Roman history. Gladiator teeth reveal signs of infant malnourishment. Evidence suggests Stonehenge was an elite cemetery.

Helen Czerski ventures beyond the visible spectrum in the final (and best) episode in this vibrant series, showing how electromagnetic radiation is so much broader than the narrow slice of reality we see with our eyes. Before delving into the details of UV, infrared and x-rays, Dr Czerski explores colour subjectivity by trying on a dress that recently divided the internet — to some it appeared blue and black, to others white and gold. It's a perfect fit. It's also a neat analogy of how people can have opposing views but both swear blind that their perspective is correct. The series ends with some amazing imaging techniques that show our bodies in a whole new light.

A documentary by Werner Herzog, who gained exclusive access to film inside the Chauvet caves of Southern France and captures the oldest known pictorial creations of humanity. Some of them were crafted as much as 32,000 years ago. The film consists of images from inside the cave as well as of interviews with various scientists and historians. Also includes footage of the nearby Pont d'Arc natural bridge.

A variety of cosmic events have both helpful and harmful effects on life on Earth. From the beauty of the Aurora Borealis and rainbows to the dangers of UV radiation and cosmic rays, from the miracle of photosynthesis to the thrill of a meteor shower, this episode explores how the effects generated by the sun and other extra-solar sources can literally get under our skin, scramble our technology, make life possible and threaten our existence all at the same time

Almost everything we know today about the beautiful giant ringed planet comes from Cassini, the NASA mission that launched in 1997 and arrived at Saturn in 2004. Since then, the space probe has been beaming home miraculous images and scientific data, revealing countless wonders about the planet, its rings and 62 moons - including some that could harbor life. When the mission approached its final days, it attempted one last set of daring maneuvers - diving between the innermost ring and the top of Saturn's atmosphere.
Aiming to skim less than 2000 miles above the cloud tops, no spacecraft has ever gone so close to Saturn, and hopes were high for incredible observations that could solve major mysteries about the planet's core. But such a daring maneuver comes with many risks and is no slam dunk. In fact, slamming into rocks in the rings is a real possibility. Join NASA engineers for the tense and triumphant moments as they find out if their bold re-programming has worked, and discover the wonders that Cassini has revealed over the years.