Sommaire pour September 2025 de BBC Science Focus Magazine

BALI, INDONESIA In the foreground of this picture is what should be a lush, verdant mangrove forest, made up of trees and shrubs that thrive in the soil and slow-moving waters found on tropical coastlines. This one’s near Pesanggaran in southern Bali and, as you can see, it’s struggling. In the background, you can see the reason why: the towering cliff face of trash looming over it from the neighbouring landfill site. Indonesia produces 3.2 million tonnes of unmanaged waste a year, much of which directly pollutes the nation’s coastlines. Mangrove forests are one of nature’s most efficient carbon sinks. They sequester CO2 four times faster than forests on land and it’s estimated that mangrove forests worldwide hold over 21 gigatonnes of CO2 (equivalent to over three years of emissions…

“There’s not really a way to tell whether another one is more likely in the coming days and weeks versus thousands of years from now” A hidden tectonic fault in Canada’s Yukon could be gearing up to unleash a major earthquake of at least magnitude 7.5, according to a new study. The Tintina fault, which runs from northeastern British Columbia through to central Alaska, has been quietly accumulating strain for at least 12,000 years. Previously thought to be relatively benign, new analysis suggests it’s still very much active. Worryingly, scientists can’t say when the next major quake will strike – only that it almost certainly will. LARGER RUPTURES “Our findings indicate that the fault is active and continues to accumulate strain,” Dr Theron Finley, lead author of the study published…

Porn in the UK just entered a new era. Thanks to the large-scale Online Safety Act interventions, gone are the days of simply ticking a box to say you’re over 18. Instead, since the end of July, anyone wanting to view such content must now pass stricter age checks by entering their credit card details, uploading photo ID or even using artificial intelligence-based facial scans. The aim of all this, according to the UK’s Department of Culture, Media and Sport (DCMS), is to keep children away from content that “would previously have been considered extreme” but has “become part of mainstream online pornography”. “When young people access this material,” the DCMS adds, “it risks normalising behaviour that might be harmful to their future emotional and psychological development.” But the impact…

Business is good for VPN providers – the companies that provide virtual private networks, encrypted tunnels through which internet data travels, that are used to spoof users’ locations. Previously, VPNs were a niche interest. They’re now used by those for whom the age verification checks on many websites imposed by the terms of the Online Safety Act are too much hassle. In the weeks after the act came into force on 25 July, VPNs shot to the top of UK app stores as people sought to protect their ID. It’s understandable that users who feel they’re being asked to hand over ever more personal information would look to VPNs. But they’re far from the only way to stay safe when you’re using the web. Go incognito? Users’ first port of…

Can’t sleep? You’re likely to be one of the 852 million people around the world who struggle to drop off, with more than 414 million of them suffering severe insomnia. Around a third of adults in Western countries experience sleep problems at least once a week and a meta-analysis from 2023 found that a quarter of adults are tired all the time. You might not expect the world’s leading sleep researchers to have trouble reaching the land of nod, but they too have nights when getting some shut-eye seems impossible. The difference is, they know more about what’s likely to be preventing them from nodding off and what to do about it. Here’s what the sleep experts say you should try if you find yourself awake in the wee small…

Astronomers love a challenge. They place their observatories on the highest mountains, in the driest deserts, on the coldest ice shelves, beneath the deepest oceans, in orbit around Earth and the Sun, and at the farthest-flung outposts of the Solar System. But now, they’re planning to build telescopes on the far side of the Moon. These instruments will probe one of the last unexplored windows on the Universe. Here, astronomers hope to get a glimpse of the elusive Cosmic Dawn, the moment when the Universe emerged from darkness, and stars and galaxies started to form (see ‘Chasing the Cosmic Dawn’, opposite). But why take on the huge technical challenges and costs of building an observatory on the Moon? The reason is that, when it comes to detecting the Cosmic Dawn,…

STOCKHOLM, SWEDEN Think back to the cell diagrams in your biology textbooks at school and you might recognise this. Except this cell isn’t one tiny part of a larger organism, it’s an organism in its own right – an amoeba. More specifically, it’s an arcella, a genus of amoeba that’s typically found in ponds, streams and marshes. As you‘ll remember from your school days, this is not how amoebas normally appear. At anywhere between 10–600 micrometres in diameter, they’re normally too small to see with the naked eye (for context, there are 1,000 micrometres in a single millimetre). This one has been magnified 60 times under the microscope of photographer Dr Håkan Kvarnström and looks fascinating as a result (even if it does resemble a particularly unappetising fried egg). Speaking…

There’s a reason some pooches tend towards plumpness, according to a recent study. Researchers at Texas A&M University, in the US, measured ‘food motivation’ by surveying more than 15,000 dog owners on their pets’ eating behaviours, as well as analysing veterinary records of each dog’s weight. A high food motivation score indicated that a dog liked to eat food (a lot) and was judged to be overweight by a vet. The study found that the sporting breeds they looked at – mainly labradors and golden retrievers – were 10 per cent more likely to have high scores compared to mixed breed dogs. Hound breeds came in second, with a 5.3 per cent increased risk of high food motivation, versus mixed breeds. This group included greyhounds and beagles. In contrast, non-sporting…

Archaeologists have discovered two strange structures lurking beneath the ground next to the world-famous pyramids of Giza in Egypt. Using radar technologies, a team of Japanese and Egyptian scientists have mapped a mysterious 10m-long (33ft) L-shaped structure, approximately 2m (6.6ft) beneath the surface – as well as a larger, deeper structure sitting about 5–10m (16–33ft) underground. It’s currently unclear exactly what the structures are, but the researchers have suggested the shallower L-shape structure could indicate an entrance to the deeper object, possibly a tomb. These discoveries were made on a large empty stretch of ground in the middle of Giza’s 4,500-year-old western cemetery. This sandy area has previously been overlooked during excavations as there are no structures visible from the surface. In contrast, the surrounding cemetery above ground is covered…

The fossilised skull shown here looks harmless now, but 70 million years ago, it belonged to an enormous animal that hunted dinosaurs. At a length of 3.35m (11.5ft) and weighing 250kg (551lb), Kostensuchus atrox was a ‘hypercarnivore’, with meat forming over 70 per cent of its diet. The beast lived just before dinosaurs went extinct, but isn’t a dinosaur itself. K. atrox is a peirosaurid crocodyliform – an extinct group of reptiles related to modern crocodiles and alligators. Researchers from Argentina’s Museo Argentino de Ciencias Naturales discovered the specimen in Southern Patagonia. During K. atrox’s reign, this area was warm and humid, and filled with freshwater floodplains where creatures like frogs, turtles and dinosaurs thrived. K. atrox is the second-largest predator ever found in this region. It’s an incredibly well-preserved…

On 21 August, in the dead of night, a mysterious spacecraft launched from NASA’s Kennedy Space Center in Florida. The craft in question was the eerily named X-37B – an experimental and highly secretive US government project that has been quietly unfolding for more than a decade. The launch marks its eighth mission in space, after racking up 4,208 days in orbit on its previous flights. Details about the X-37B and its mission remain scarce. Over the years, only a trickle of information has emerged, allowing us to piece together fragments of what’s happening above our heads. While the race to return to the Moon plays out in full view – driven by private corporations and national space agencies – another, more shadowy contest is unfolding behind the scenes: the…

Astonishingly, earthquakes shake the US state of California almost 9,000 times a year, on average – that’s about once every hour. California’s official nickname is the Golden State, harking back to the mid-19th-century gold rush that saw its population explode in just four years, from 14,000 to a quarter of a million. But if you’ve ever been lucky enough to visit and felt the ground move beneath your feet, you’ll probably agree that ‘the Earthquake State’ is a far better fit. None of this should be a surprise given that it hosts the San Andreas Fault, where two of the world’s great tectonic plates – the North American plate to the east and the Pacific plate to the west – meet. California has attracted the world’s attention in recent years,…

The Universe was born hot and dense. Eventually, about 380,000 years after the Big Bang, it had cooled enough for protons and electrons to combine and form neutral atoms of mainly hydrogen and helium. This early epoch is known as the cosmic ‘Dark Ages’ because neutral hydrogen absorbed photons, making the Universe opaque. But as the first stars and galaxies began to coalesce, roughly 100 million years later, that hydrogen gas gradually became ionised (stripped of electrons) by ultraviolet radiation. Marking the beginning of the ‘epoch of reionisation’, this Cosmic Dawn is when the Universe first became transparent to light. Precisely when the Cosmic Dawn occurred is a matter of debate, but the process appears to have ended about 1.1 billion years after the Big Bang.…

It was Pablo Picasso who said – with some painterly flamboyance I – that, “Art washes away from the soul the dust of everyday life.” It’s good for you – is what I think he was getting at. Some 50 years after Picasso’s death, it’s beginning to look like he was right. Researchers are learning that the health benefits of creating or consuming art are anything but abstract. It can have genuine physiological and psychosomatic effects. Just looking at art can lower a person’s heart rate, blood pressure and cortisol levels, sometimes in real time. Some artsy activities can even reduce markers of inflammation in the body or improve neuroplasticity in the brain. There are targeted creative therapies, too. In 2020, the English National Opera and Imperial College London rolled…

Cats who develop dementialike symptoms in old age have similar changes in their brains to humans with Alzheimer’s, a new study has found. The findings could open the door to new research, possibly helping us discover therapies for the notoriously difficult-to-treat disease. “Compared to other diseases, our progress in treating Alzheimer’s has been fairly poor,” Dr Robert McGeachan, lead author of the study, told BBC Science Focus. “Cats could be a better, more relevant model for the disease because we’re seeing similar things happening in the brain. By studying Alzheimer’s in cats, we can perhaps develop treatments that are more likely to be successful in humans.” Alzheimer’s is the most common form of dementia, a collection of neurodegenerative diseases affecting people’s memory, problem-solving, language and behaviour. Roughly 1 in 9…

The nature of time is one of the most profound and longstanding problems in physics - one that no one can agree on. From our perspective, time seems to steadily progress forward with each tick of the clock. But the closer we look, the more bizarre time becomes - from equations that state time should flow as freely backwards as it does forwards, to the strange quantum realm where cause and effect can flip on their heads. Could it even be that time itself is an illusion? What makes time so confounding is that we have three very different ways of defining it, which don’t easily fit together. The first definition comes from the equations that describe how things change over time. We have many such equations describing everything from…

The idea that humans might communicate through chemical signals called pheromones has captivated scientists and the public for decades, inspiring countless studies in search of proof. In animals, pheromones are well understood. Ants follow chemical trails to navigate and communicate, dogs mark their territory with scent signals, and moths release airborne pheromones to attract mates. But whether humans do the same is trickier question. Could someone really trigger a physical or emotional reaction in another person without them even realising? Could it tip the scales of attraction? After more than 60 years of searching, the answer remains elusive – though new findings suggest we may finally be closing in on it. FIRST WHIFFS In 1959, Adolf Butenandt and his team discovered the first pheromone, bombykol, a chemical released by female…

When European scientists first set eyes on the platypus, in the form of a pelt and a sketch shipped over from Australia in 1798, they couldn’t believe it. The specimen was so bizarre that English zoologist George Shaw said it was impossible not to question its authenticity. Had a prankster sewn the beak of a duck onto the body of a beaver? To make sure, he examined the specimen thoroughly to check for any stitches. With no seam in sight, Shaw became the first to formally describe the animal. He dubbed it Platypus anatinus, aka ‘duck-like flat-foot,’ but in time this was refined to Ornithorhynchus anatinus, aka ‘duck-like bird-snout.’ The platypus looks as though someone took one of those children’s books where hinged sections depict the head, middle and bottom…

On 21 September, Saturn will be in a position known as opposition – opposite the Sun in the sky. Imagine a straight line from Saturn, passing through Earth and towards the Sun. This alignment is rarely perfectly straight, Saturn typically being a little above or below Earth’s orbital plane, but it’s close enough. When this happens, the distance between Earth and Saturn is minimised, and the planet appears at its brightest and largest when looked at through a telescope. Astronomers look forward to the weeks surrounding opposition, knowing that this is when they’ll get the best views. You can locate Saturn using our chart (Diphda and Fomalhaut are the brightest stars below Saturn) and once found, there are several other things to look out for. First is Neptune, which currently…