This episode tells the story of how the Emperor Constantine brought Christianity to the western world. In AD 312, Rome was in crisis. The empire had been divided into four parts, each with its own emperor who fought one another. Constantine intervened and united Rome, using military might and a new religion - Christianity.

It's a golden age for planet hunters: recently, they've discovered more than 750 planets orbiting stars beyond our sun. Some of them, like a planet called Kepler-22b, might even be able to harbor life. What would that life look like? Combining startling animation with input from expert astrobiologists, Alien Planets Revealed takes viewers on a journey of the imagination as we 'build' aliens from the ground up. What chemical building blocks will make up their genetic code? How will life get started and how will the exotic environment on a planet like Kepler-22b drive evolution? Bringing the creative power of veteran animators together with the latest discoveries in astrobiology, Alien Planets Revealed provides a glimpse of the creatures we might one day encounter beyond our solar system.

Playing with Nuclear Fire' - In March 2011, the Tohoku earthquake in Japan created a tsunami that killed some 16,000 people and crippled the Fukushima Daiichi nuclear power plant. In the aftermath, the government and TEPCO, the plant's operator, withheld information about the extent of the damage. Three years later, citizens and the international community are left wondering if Japan really does have the situation under control, as the government is insisting, or if the danger is far greater than anyone is willing to admit. 'No Man Left Behind' - It's estimated that over a quarter million vets from recent wars have sought treatment for PTSD. Despite these statistics, veterans often face an uphill battle to get treatment, receiving inadequate attention and, most dangerously, overprescribed narcotics and other pharmaceuticals. Ryan Duffy meets veterans struggling with mental illness and addiction.

The plant eaters take on the largely indigestible, spiny and poisonous defences of plants with some spectacular physical adaptations to diet. Plant Predators demonstrates the particular (and often peculiar) adaptations of herbivores

Fathom is a visual and aural wonder of a documentary that follows researchers working to finally decode the communication of humpback whales. Dr. Ellen Garland and Dr. Michelle Fournet embark on parallel journeys on opposite sides of the world, as they seek to better understand whale culture and communication. The film uniquely reveals a deep commitment and reverence to the scientific process and the universal human need to seek answers about the world around us.
From hypothesis to groundbreaking experiences in the field, 'Fathom' showcases the passion, curiosity, collaboration, perseverance and work it takes for leading scientists to make scientific discoveries.

NASA’s Space Launch System (SLS) is the most powerful rocket ever built. This is the story of the incredible engineering that went into building it, told first-hand by NASA’s best rocket engineers. Building the rocket that will take us back to the Moon is no easy task, but the payoff will be phenomenal.