Tyson begins the episode by explaining the nature of the speed of light and how much of what is seen of the observable universe is from light emanated from billions of years in the past. Tyson further explains how modern astronomy has used such analyzes via deep time to identify the Big Bang event and the age of the universe. Tyson proceeds to describe how the work of Isaac Newton, William Herschel, and James Clerk Maxwell contributed to understanding the nature of electromagnetic waves and gravitational force, and how this work led towards Albert Einstein's Theory of Relativity, that the speed of light is a fundamental constant of the universe and gravity can be seen as distortion of the fabric of space-time. Tyson describes the concept of dark stars as postulated by John Michell which are not visible but detectable by tracking other stars trapped within their gravity wells, an idea Herschel used to discover binary stars. Tyson then describes the nature of black holes, their enormous gravitational forces that can even capture light, and their discovery via X-ray sources such as Cygnus X-1. Tyson uses the Ship of Imagination to provide a postulate of the warping of spacetime and time dilation as one enters the event horizon of the black hole, and the possibility that these may lead to other points within our universe or others, or even time travel. Tyson ends on noting that Herschel's son, John would be inspired by his father to continue to document the known stars as well as contributions towards photography that play on the same nature of deep time used by astronomers.

The centre of our galaxy is home to an invisible monster of unimaginable power – a supermassive black hole named Sagittarius A star, with four million times the mass of the Sun. Recent astronomical breakthroughs have confirmed not only that black holes like Sagittarius A star exist, but that these bizarre invisible objects may be the ultimate galactic protagonists.
Stunning CGI takes us back to witness the fiery origins of our galaxy’s black hole 13.6 billion years ago, when the early universe was home to colossal blue stars, and when they ran out of fuel, they collapsed under their own enormous mass, crushing down into an object so small and so dense it punched a hole in the fabric of the universe. Over billions of years, Sagittarius A star feasted on nearby gas, stars, and through cataclysmic mergers with other black holes. A breakthrough discovery by Nasa’s Fermi gamma-ray telescope has shown that our black hole had the power to sculpt the entire galaxy, creating vast bubbles of gas above and below our galaxy and even protecting stars systems as ours.
In a mind-bending conclusion, Brian Cox reveals how our modern understanding of black holes is challenging our concepts of reality to the breaking point. In trying to understand the fate of objects that fall into Sagittarius A star, scientists have come to a stunning conclusion: space and time, concepts so foundational to how we experience the world around us, are not as fundamental as we once thought.

Spy in the Huddle use innovative techniques to reveal the incredible secrets of your pets' behaviour in ways never seen before. As astonishing photography explores the wild side of our playful pets, find out why hamsters love to run in a wheel, how dogs pick up the rules of the pack and how kittens learn to be solitary hunters. Featuring incredible views of plunge-diving dogs, babysitting cats, acrobatic hamsters and a playful cat outwitted by his prey" - you'll never look at your favourite companions in quite the same way again. The latest science also reveals why budgies talk, how a cat scales a vertical wall with the help of a special claw, why hamsters stuff their faces with more food than they can eat and the real meaning behind a rabbit's hop. Our pets are also given a chance to explore their wild side as we join the free-roaming pet dogs of Cusco Peru, pet rabbits living in a natural warren and the wild-living inhabitants of Cat Island, Japan. A range of innovative techniques such as moving X-rays, thermal imagery, minicam-carrying dogs and revelatory slow-motion photography shows why our pets play and how their true wild nature is just a whisker away.

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.

Within the earth, right beneath our feet, are strange and sometimes deadly secrets. Earthquakes, tsunamis, and volcanic eruptions are just some of the phenomena that are driven by hidden forces deep inside our planet. With the latest sensors and surface scans, a virtual X-Ray of the earth can be generated for study.
In the first episode, we will explore how a vast fault 80 miles off the Pacific Northwest coast. With pressure building for over 300 years, a slip would result in a megaquake and tsunami that will devastate the region threatening 15 million people.

The human eye is a remarkable piece of precision engineering, but it is also extremely limited. Beyond the narrow range of light that makes up the familiar colours of the rainbow is a vast spectrum of light, entirely unseen. Richard Hammond does just that, using ground-breaking new imaging technologies to take the viewer on a breath-taking journey of discovery beyond the visible spectrum, seeing the world, quite literally, in a whole new light. From death-defying aerial repairmen in the United States using ultraviolet cameras to seek out an invisible force that lurks unseen on power lines, to German scientists unlocking the secrets of animal locomotion with the world's most powerful moving x-ray camera, to infrared cameras that can finally reveal the secrets within a humble beehive, he shows how new technologies are letting us see our world anew.