Professor Brian Cox continues his epic exploration of the cosmos by looking at the faint band of light that sweeps across the night sky - our own galaxy, the Milky Way. The Sun is just one of almost 400 billion stars that form this vast, majestic disk of light, our own home in the universe. Thanks to a cutting-edge space we’re finally able to reveal the Milky Way’s dramatic history and predict its cataclysmic future.
Our galaxy started out a fraction of the size it is today, and Gaia telescope has revealed how it grew over the eons. Beautifully rendered VFX based on the very latest Gaia data has uncovered the remarkable story of our galaxy’s evolution. As our young galaxy encountered rival galaxies, it experienced a series of violent growth spurts and intense periods of cataclysmic change while battling to survive. Each time our galaxy feeds, a new era of star formation begins, fuelled by incoming torrents of fresh gas and energy. And there is another collision to come. Another, larger galaxy is coming our way. Andromeda is heading straight for us at a quarter of a million miles per hour. The Milky Way’s long-term fate is in the balance.

The meteoric rise of renewable energy has consequences for our electricity supply. While coal and gas fired power stations can generate electricity whenever you need it, renewables are intermittent by nature. So we need a backup plan for when the wind stops or the sun goes down.
All over the world, engineers and scientists are racing to solve one key problem; how to safely and efficiently store electricity at a huge scale but at a low cost. The quest is producing some truly remarkable ideas and this episode details three of them.

Even as the science grew more certain, the oil industry continued to block action to tackle climate change in the new millennium. In a revelatory interview, Christine Todd Whitman, George W. Bush's former environment chief, tells the story of how the industry successfully lobbied President Bush to reverse course on his campaign promise to regulate carbon emissions.
Tensions grew between two of the world's biggest oil companies, ExxonMobil and BP, after the latter publicly called for action to tackle climate change. The election of Barack Obama provided hope for supporters of climate action, but the billionaire Koch brothers made an effort to block the new president's attempts to pass climate change legislation, and climate denialism became the mainstream position of the Republican Party. A lawyer who worked for Koch brothers through this period speaks on camera for the first time.

The last chapter explains how the 2010s became another lost decade in the fight against climate change – as the move to natural gas delayed a transition to more renewable sources of energy.
Engineer Tony Ingraffea, in the 1980s, helped develop a new technique for extracting gas and oil from shale rock, which ultimately became known as 'Fracking'. It was to unleash vast new reserves of fossil fuels and was promoted as a cleaner energy source. But Ingraffea explains how he later came to regret his work when he realized that gas could be even worse for climate change than coal and oil.
Dar-Lon Chang, a former ExxonMobil engineer, speaks for the first time on camera alleging that as the company increased its natural gas operations, it was not sufficiently monitoring methane leaks that were contributing to climate change. Now, after a year of unprecedented wildfires, drought and other climate-related disasters, multiple lawsuits are being brought in US courts in efforts to hold Big Oil legally accountable for the climate crisis.

All of our pets survived for thousands of years in the wild without any help from us, and this has led them to develop astonishing athletic abilities which we sometimes take for granted. As greyster dogs and endurance champ tortoises.
Dog scootering uses one or more dogs to pull a human riding an unmotorized scooter. Greysters are a naturally-athletic breed that can run at 20 miles per hour for five miles while handling these carriages. No other animal can run at this speed, exerting this power, and expending this energy for so long. So, what's their secret? Greysters' stride length can be a staggering 16 feet and they are super efficient at absorbing and using oxygen. Greyster dogs have nearly twice mitochondria inside their cells than humans.

Experts explore the elusive endeavor of determining the age of the cosmos. Understanding the age of the universe is fundamental to understanding the universe at all. It's at the heart of everything. We want to know how much mass is in it, how much energy is in it, how it behaves. We have to have this number nailed down. The age of the universe enables us to not only understand where we came from, but potentially, the fate of the universe, what will happen millions and billions of years from now.
The idea that the universe grew from a ball smaller than a pinhead is hard to understand, but figuring out when it happened sounds like it should be more straightforward. But it turns out, getting the age of the universe is pretty tricky.