What does it take to make a nuclear weapon?

In an interview last weekend, Iran’s ambassador to the UN said his country’s nuclear enrichment ‘will never stop’ because it is permitted for ‘peaceful energy’ purposes. It is the latest development in an escalation of tensions over Iran’s nuclear programme, which erupted when Israel targeted the country’s nuclear facilities in June. To understand why enrichment is so important, Madeleine Finlay talks to Robin Grimes, professor of materials physics at Imperial College London. He explains what goes into creating a nuclear weapon, and why getting to the stage of weaponisation is so difficult. Help support our independent journalism at theguardian.com/sciencepod

It has been 25 years since Bill Clinton announced one of humanity’s most important scientific achievements: the first draft of the human genome. At the time, there was a great deal of excitement about the benefits that this new knowledge would bring, with predictions about curing genetic diseases and even cancer. To find out which of them came to pass, and what could be in store over the next two-and-a-half decades, Madeleine Finlay is joined by science editor Ian Sample, and hears from Prof Matthew Hurles, director of the Wellcome Sanger Institute. Help support our independent journalism at theguardian.com/sciencepod

Ever since Pluto was demoted from planet to dwarf planet in 2006, astronomers have been wondering whether Neptune really is the most distant planet from the sun. Now, a new telescope could uncover what lies in the farthest reaches of the solar system. The Vera C Rubin Observatory released its first images this week, and soon the world’s most powerful digital camera will be pointing across the whole of the night sky. Scientists are hopeful that if planet nine exists, the telescope will find it within its first year of operation. Ian Sample is joined by Dr Scott Sheppard, an astronomer at the Carnegie Institution for Science, to find out how Pluto lost its planetary status, why scientists think there could be another super-Earth, and why planet nine has been so hard to find. Help support our independent journalism at theguardian.com/sciencepod

More of us are turning to products containing mushroom extracts, with the medicinal fungi market now worth billions of pounds. Promises of benefits to mental and physical health have seen its popularity spill over from wellness influencers to the shelves of Marks & Spencer – but is there any scientific evidence behind these claims? Ian Sample chats to Madeleine Finlay about the appeal of mushroom drinks and supplements, and hears from the mycologist Prof Nik Money on what we really know about how fungi can affect our minds and bodies. Help support our independent journalism at theguardian.com/sciencepod

The chancellor, Rachel Reeves, has promised £14bn of investment to build the Sizewell C nuclear power plant, kicking off what the energy secretary, Ed Miliband, says will be a ‘golden age for clean energy abundance’. But for critics, the technology’s high costs and lengthy construction times have always eclipsed the benefits of abundant low-carbon electricity. Ian Sample is joined by the Guardian energy correspondent Jillian Ambrose to find out why the UK government is backing nuclear and whether it will help Britain hit its target of net zero by 2050. Help support our independent journalism at theguardian.com/sciencepod

As a companion to the Guardian’s Missing in the Amazon podcast, global environment editor Jon Watts goes in search of answers to the question Dom Phillips was investigating when he was murdered: how can we save the Amazon? In the final episode of a three-part series, Jon encounters a radical new view of the Amazon’s history being uncovered by archaeologists. Far from an uninhabited wilderness, the rainforest has been shaped by indigenous peoples for thousands of years. Jon finds out how their expert knowledge could be harnessed to secure the Amazon’s future. Help support our independent journalism at theguardian.com/sciencepod

As a companion to the Guardian’s Missing in the Amazon, Jon Watts, global environment editor, goes in search of answers to the question Dom Phillips was investigating when he was murdered: how can we save the Amazon? In episode two, Jon meets the people trying to make sure the rainforest is worth more standing than cut down – from a government minister attempting to establish Brazil’s ‘bioeconomy’ to a startup founder creating superfood supplements and a scientist organising night-time tours hunting for bioluminescent fungi. Jon explores new ways of finding value in the forest and asks whether they will be enough to secure its future survival. Help support our independent journalism at theguardian.com/sciencepod

As a companion to the Guardian’s Missing in the Amazon, the global environment editor Jon Watts goes in search of answers to the question Dom Phillips was investigating when he was murdered: how can we save the Amazon? In episode one of a three-part series, Watts explores what’s at stake if we fail to act in time. He hears about the crucial role of the rainforest for South America and the global climate, and looks back at how cattle ranching came to dominate and destroy huge swathes of the forest – pushing it to a dangerous tipping point today. Help support our independent journalism at theguardian.com/sciencepod

The British journalist Dom Phillips and the Brazilian indigenous defender Bruno Pereira vanished three years ago while on a reporting trip near Brazil’s remote Javari valley. The Guardian’s Latin America correspondent, Tom Phillips, investigates what happened to them in a six-part podcast series. Find episode 2 and all future episodes by searching for Missing in the Amazon. Help support our independent journalism at theguardian.com/sciencepod

Vast areas of the ocean are getting darker, according to research based on satellite imaging. Marine ecosystems are governed by faint light changes – from mass nightly migrations to coral spawning cycles – so what happens when that light begins to fade? Ian Sample talks to Prof Tim Smyth from the Plymouth Marine Laboratory about why this darkening is happening and how life in the ‘photic zone’ – the sunlit upper layer that is home to 90% of marine organisms – could be profoundly affected Planet’s darkening oceans pose threat to marine life, scientists say. Help support our independent journalism at theguardian.com/sciencepod