On the coast, two worlds collide. Coasts are the most dynamic and challenging habitats in the ocean - that brings great rewards but also great danger. The extraordinary animals that live here must find ingenious ways to cope with two very different worlds. This episode is a rollercoaster ride of heart-stopping action and epic drama, peopled with characters from the beautiful to the bizarre. We meet fish that live on dry land and puffins that must travel 60 miles or more for a single meal, and witness a life-and-death struggle in a technicolour rock pool. In a secluded cove in the Galapagos, sea lions feast on 60kg tuna. It should be impossible - tuna are usually far too fast for sea lions to catch. But here the sea lions club together to herd their prey inshore. Once trapped in the shallows, these huge fish are easy pickings. As the tide recedes in Brazil, lightfoot crabs leap from rock to rock, desperately avoiding the water - their lives depend on it. Moray eels launch themselves from rock pools, jaw gaping. Then octopuses, too. Both crawl across dry rock to set their ambush. Elsewhere, the ever-changing tides create rock pools. But these temporary worlds are a battleground. Predatory starfish turn a magical garden into the stuff of nightmares.

Professor Brian Cox fulfils a childhood dream by going behind the scenes at Nasa’s Jet Propulsion Laboratory (JPL), mission control for Mars 2020 – one of the most ambitious missions ever launched that may finally reveal if life ever existed on the red planet.
In 1980, a young Brian Cox wrote to JPL asking for photos from some of their missions to the planets. The pictures they sent him from Voyager and the Viking mission to Mars were a source of inspiration that set him on the path to becoming a physicist.
Now, over 40 years later, he has been granted privileged access to JPL, including key mission areas that are usually off-limits to film crews. Brian spends a week following the team who guide the Perseverance rover and the Ingenuity helicopter - the first powered aircraft ever sent to another planet - across the surface of Mars during a critical stage of the mission.
Perseverance’s goal is to search for signs of long extinct life on the surface of Mars in an area called Jezero Crater, which, 3.8 billion years ago, was filled by a vast lake. If it finds evidence of that life, it could change everything we know about life in the universe - and even transform our understanding of our own origins.

The planets of our solar system have experienced epic catastrophes throughout their long history, both raining down from outside and bubbling up from within. We'll voyage back in time to investigate the violent events that profoundly shaped the planets, including earth itself. We'll witness stunning revelations about what transformed Mars into a barren, hostile desert... The disaster that changed Venus from temperate to hellish... The impact that blew away Mercury's mantle, turning it into a planetary core... A colossal disturbance that rearranged the orbits of the gas giants... Titanic impacts on Jupiter... And how a lost moon may finally explain Saturn's rings.

The Cave of Swallows in Mexico is a 400m vertical shaft, deep enough to engulf the Empire State Building. The Lechuguilla cave system in the USA is 193km long and 500m deep with astonishing crystal formations hanging from its chambers. Although often overlooked, caves are remarkable habitats with equally bizarre wildlife. Cave angel fish cling to the walls behind cave waterfalls with microscopic hooks on their flattened fins. Cave swiftlets navigate by echo-location and build nests out of saliva. The Texas cave salamander has neither eyes nor pigment. Unique access to a hidden world of stalactites, stalagmites, snotites and troglodytes brings a wealth of surprises.

Coral reefs are the nursery for all life in the oceans, a remarkable ecosystem that sustains us. Yet with carbon emissions warming the seas, a phenomenon called 'coral bleaching' -a sign of mass coral death- has been accelerating around the world, and the public has no idea of the scale or implication of the catastrophe silently raging underwater.
Chasing Coral taps into the collective will and wisdom of an ad man, a self-proclaimed coral nerd, top-notch camera designers, and renowned marine biologists as they invent the first time-lapse camera to record bleaching events as they happen. Unfortunately, the effort is anything but simple, and the team doggedly battles technical malfunctions and the force of nature in pursuit of their golden fleece: documenting the indisputable and tragic transformation below the waves. With its breathtaking photography, nail-biting suspense, and startling emotion, Chasing Coral is a dramatic revelation that won't have audiences sitting idle for long.

In part two, Professor Al-Khalili looks at the 19th century chemists who struggled to impose an order on the apparently random world of the elements. From working out how many there were to discovering their unique relationships with each other, the early scientists' bid to decode the hidden order of the elements was driven by false starts and bitter disputes. But ultimately the quest would lead to one of chemistry's most beautiful intellectual creations - the periodic table.