The heaviest thing in the Galaxy has now been imaged by the biggest telescope on Earth. This is Sagittarius A*, the supermassive black hole at the centre of our Galaxy – a gas and star-consuming object, a 4 million times the mass of the Sun. The Event Horizon Telescope is not one device but a consortium of radio telescopes ranging from the South Pole to the Arctic Circle. Their combined data allowed astronomers to focus in on this extreme object for the first time. Astronomer Ziri Younsi from University College London talks to Roland Pease about the orange doughnut image causing all the excitement.Also in the programme…Climatologist Chris Funk talks about the role of La Niña and climate change in the record-breaking two year drought that continues to threaten the lives and livelihoods of millions of people in East Africa.Was a pig virus to blame for the death of the first patient to receive a pig heart transplant? We talk to the surgeon and scientist at the University of Maryland School of Medicine who led the historic animal to human transplant operation this year.How easy will it be to grow plants in lunar soil on future moon bases? Plant biologist Anna Lisa Paul has been testing the question in her lab at the University of Florida, Gainesville, with cress seeds and lunar regolith collected by the Apollo missions. Photo: First image of Sgr A*, the supermassive black hole at the centre of our galaxy Credit: EHT Collaboration, Southern European ObservatoryPresenter: Roland Pease Producer: Andrew Luck-Baker

The Mekong Delta is home to 17 million people and is Vietnam’s most productive agricultural region. An international group of scientists warn this week that almost all of the low lying delta will have sunk beneath the sea within 80 years without international action. Its disappearance is the result of both sea level rise and developments such as dams and sand mining.Also in the programme: using the rumbling of traffic in Mexico City to monitor earthquake hazard, record-breaking quakes on Mars and a record-breaking high jumping robot.Photo: Mekong River in Kampong Cham, Cambodia Credit: Muaz Jaffar/EyeEm/Getty ImagesPresenter: Roland Pease Producer: Andrew Luck-Baker

Deadly heat has been building over the Indian sub-continent for weeks and this week reached crisis levels. India experienced its hottest March on record and temperatures over 40 degrees Celsius (and in some places approaching 50 degrees) are making it almost impossible for 1.4 billion people to work. It’s damaging crops and it’s just what climate scientists have been warning about. Roland Pease talks to Vimal Mishra of the Indian Institute of Technology in Gandhinagar about the impact and causes of the unprecedented heatwave.What could be behind the incidence of hepatitis in young children around the world in recent months? Ordinarily, liver disease in childhood is extremely rare. Could a virus normally associated with colds be responsible or is the Covid virus involved? Roland Pease talks to virologist William Irving of Nottingham University.Also in the programme: how climate change is increasing the likelihood of animal viruses jumping the species barrier to humans with global change modeller Colin Carlson of Georgetown University, and myths about the personalities of dog breeds are exploded with new research by Elinor Karlsson of the University of Massachusetts Medical School.(Photo: Woman cooling herself in India heatwave Credit: Debajyoti Chakraborty/NurPhoto via Getty Images)Presenter: Roland Pease Producer: Andrew Luck-Baker

As a series of UN climate reports have warned recently, drastic reductions in greenhouse gas emissions – a halving over the next decade – are needed if we are to keep global warming down to manageable levels. No sign of that happening. An emergency measure to buy time that’s sometimes discussed is solar geoengineering – creating an atmospheric sunscreen that reduces incoming solar heat. Sulphate compounds in volcanic gases or in industrial fumes attract water vapour to make a fine haze and have that effect. The difference would be starting a deliberate programme of injecting sulphate particles into the stratosphere. There are a host of arguments against it, including a revulsion against adding another pollutant to the atmosphere to offset the one, carbon dioxide, that’s giving us problems in the first place. Another objection, outlined this week, is that it could set back the global fight against malaria - a major killer in its own right. University of Cape Town ecologist Chris Trisos tells Roland Pease what his team’s modelling study revealed.Yale University neurologist Kevin Sheth talks to us about a revolution in medical scanning – small-scale MRI machines that can be wheeled to the patient’s bedside. According to palaeontologist Maria McNamara, an amazingly preserved pterosaur fossil from Brazil proves that some of these flying reptiles did have feathers similar to those of birds (and some dinosaurs), and that the feathers were of different colours, possibly for mating display. Primatologist Adrian Barnett has discovered that spider monkeys in one part of the Brazilian Amazon seek out fruit, full of live maggots to eat. Why?Presenter: Roland Pease Producer: Andrew Luck-Baker(Photo: Illustration of a mosquito biting Credit: SCIEPRO/Science Photo Library/Getty Images)

Brain scanning experiments reveal how psilocybin works to relieve severe depression. Psilocybin is the psychedelic substance in 'magic mushrooms'. The psychoactive chemical is currently in clinical trials in the UK and US as a potential treatment for depression and other mental illnesses. Professor David Nutt of Imperial College London tells Roland about the research Also in the show, worrying findings about the increase in premature deaths because of air pollution in growing cities in tropical Africa and Asia. An international group of climatologists has found that the tropical storms which struck Mozambique, Malawi and Madagascar in early 2022 had been made more intense by human-induced climate change. And astronomer David Jewitt used the Hubble telescope to measure the largest known comet in the solar system - it's huge at about 120 kilometres across.(Image: Mexican Psilocybe Cubensis. An adult mushroom raining spores. Credit: Getty Images)Presenter: Roland Pease Producer: Andrew Luck-Baker

Just over two months ago, the undersea volcano of Hunga Tonga erupted catastrophically, generating huge tsunamis and covering the islands of Tonga in ash. University of Auckland geologist Shane Cronin is now in Tonga, trying to piece together the sequence of violent events. Edinburgh University palaeontologist Ornella Bertrand tells us about her studies of the ancient mammals that inherited the Earth after the dinosaurs were wiped out. To her surprise, in the first 10 million years after the giant meteorite struck, natural selection favoured larger-bodied mammals, not smarter ones.At the University of Bristol, a team of engineers are developing skin for robots, designed to give future bots a fine sense of touch. Roland shakes hands with a prototype.A global satellite survey of the world’s largest coastal cities finds that most of them contain areas that are subsiding faster than the rate that the sea level is rising. Some cities are sinking more than ten times faster, putting many millions of people at an ever-increasing risk of flooding. Oceanographer Steven D’Hondt at the University of Rhode Island explains why this is happening. (Image: An eruption occurs at the underwater volcano Hunga Tonga-Hunga Ha"apai off Tonga, January 14, 2022. Credit: Tonga Geological Services/via Reuters)Presenter: Roland Pease Producer: Andrew Luck-Baker

Russian forces in the forested exclusion zone around the Chernobyl nuclear site may be receiving potentially dangerous levels of radiation. After the nuclear accident trees were felled and radioactive material was buried across the site. As the forest regrew its took up much of that radiation - making it the most radioactive forest in the world according to Tom Scott from Bristol University who studies radiation levels in the region. The troop's activities, from digging trenches to lighting fires as missiles are fired, may be releasing radiation. Its unclear how dangerous this is, but those with the greatest and most immediate exposure risk are the troops themselves.Australia’s iconic Great Barrier Reef has suffered a mass bleaching event – where coral can be killed by rising temperatures. This is the latest in a series of such events which also affect other reefs. Kate Quigley from The Australian Institute of Marine Science is working to breed corals that can be more heat tolerant. However, she says this is not a solution in itself without addressing climate change and continued ocean warming. Understanding the human genome has reached a new milestone, with a new analysis that digs deep into areas previously dismissed as ‘junk DNA’ but which may actually play a key role in diseases such as cancer and a range of developmental conditions. Karen Miga from the University of California, Santa Cruz is one of the leaders of the collaboration behind the new findings.And can fish do maths? Yes according to Vera Schlussel from the University of Bonn. Her group managed to train fish in both addition and subtraction. (Image: Radiation hazard sign in Pripyat, a ghost town in northern Ukraine, evacuated the day after the Chernobyl disaster. Credit: Getty Images)Presenter: Roland Pease Producer: Julian Siddle

Unseasonably high temperatures have been recorded in both polar regions. Glaciologist Ruth Mottram discusses why they might be occurring now and the potential impact on her own work measuring climate change in Greenland.Erica Ollmann Saphire from the La Jolla Institute for Immunology tells us about her work developing new treatments for Ebola, she is looking to develop drugs which work not just on Ebola but also a range of related Viruses. And Eugene Koonin from the United States National Institutes of Health shows us how his computer modelling of the mutations of Sars Cov -2 suggest some good news - that the virus might not be able to mutate into further dangerous forms – at least not with its current set of genetic tools. Eugene is originally from Russia and both he and President Obama’s science advisor John Holdren are keen to keep up ties with scientists in Russia despite the international sanctions now being applied over the war in Ukraine. Both point out that many Russian scientists have opposed the war, and that curtailing scientific collaboration could have a detrimental effect not just on science in Russia but elsewhere as well. Image: Penguins on an ice float, Paradise Harbor, also known as Paradise Bay, behind Lemaire and Bryde Islands in Antarctica. Credit: Leamus via Getty Images)Presenter: Roland Pease Producer: Alex Mansfield

Analysis of wastewater from sewage systems has provided an early warning system for the presence of Covid-19 in communities – showing up in the water samples before people test positive. It’s also possible to identify the variants and even specific genetic mutations. Davida Smyth of Texas A&M University has been using this technique in New York and found intriguing results - forms of the virus not present in humans. The suggestion is that mutated forms may be infecting other animals, possibly those present in the sewers. An analysis of long Covid, symptoms of fatigue, and ‘brain fog’ which occur long after initial infection, show that around a quarter of those infected develop these symptoms. Lucy Cheke of Cambridge University discusses the implications.The war in Ukraine has highlighted the importance of the region in supplying raw materials and energy to other countries, gas, cereal crops, and fertilisers in particular. As crop scientist John Hammond from Reading University explains, the stopping of fertiliser exports from Russia, in particular, could impact food security in many countries. And with unseasonal fires already burning in the Western US Caroline Juang of Columbia University’s Earth Observatory gives us her analysis of the driving factors in the intensification of fires year-on-year.(Image: USA, New York, steam coming out from sewer. Credit: Westend61/Getty Images)Presenter: Roland Pease Producer: Julian Siddle

Hong Kong had been very successful at preventing the spread of Covid-19. Testing and isolation measures were very effective. However, vaccine uptake was low amongst elderly people and that says virologist Malik Peiris has now left them vulnerable to the highly infectious Omicron variant. The bombing of a scientific institute in the Ukrainian city of Kharkiv has echoes of the Stalinist purges says physicist and historical Mikhail Shifman. He tells us how the institute developed as a leading centre for physics in the 1930s, but scientists there fled or were murdered after being targeted by Stalin’s regime.Economic sanctions and other measures designed to isolate Russia are likely to have an impact on Russian participation in international scientific collaborations. Nikolay Voronin from the BBC’s Russian Service gives us his assessment of the immediate impact and, if the conflict continues long term, the potential for Russian science to retreat the kind of isolation last seen during the cold war.Presenter: Roland Pease Producer: Julian Siddle(Photo: Patients wearing face masks rest at a makeshift treatment area outside a hospital, following a Covid-19 outbreak in Hong Kong, 2 March, 2022. Credit: Tyrone Siu/Reuters)