2026-08-11の世界

Astronomers have captured the sharpest visible-light picture of the Sun ever taken, and it shows something scientists had only guessed at before. The image comes from the Inouye Solar Telescope in Hawaii, the world's most powerful solar telescope. It reveals swirling, wave-like patterns rippling across the Sun's surface, similar to shapes that clouds sometimes make in Earth's sky. These patterns form through a process called the Kelvin-Helmholtz instability, which happens when two streams of material flow past each other at different speeds. Scientists had long suspected this process shapes the Sun's boiling surface, but nobody had proven it with a clear picture until now. The area shown in the new image spans roughly the width of Earth, yet each individual swirl is only about the size of a city. Researchers say studying these small structures could help explain how energy and heat move through the Sun's outer atmosphere, the corona, which is mysteriously hotter than the surface below it.

For centuries, the dodo has been remembered as a slow, clumsy, and not very smart bird that deserved to disappear. New research suggests that reputation is unfair. Scientists used CT scanners to study the skulls of three dodos, their closest relative the Rodrigues solitaire, and various living pigeons kept in museums around the world. The results showed that the dodo's forebrain, the part of the brain linked to thinking and memory, was about the same size as in other pigeons. According to researcher Andrew Iwaniuk, there is no evidence that the dodo was any less intelligent than its relatives. The scans also revealed some surprises. The dodo had small optic lobes but slightly larger eyes, which may have given it blurrier vision but better sensitivity in low light. It also had an unusually large brain region linked to smell, unlike most of its pigeon relatives. Together, these features suggest the dodo may have been active around dawn and dusk, relying on smell as much as sight to find food on its home island of Mauritius.

A tiny amount of ancient DNA has given scientists a rare, detailed look at the people who lived in Japan thousands of years ago. Researchers led by Koji Ishiya at Kanazawa University reconstructed the genome of a woman known as IY1, who lived during the Initial Jomon period about 8300 years ago, with each part of her DNA sequenced roughly 67 times over. This kind of discovery is unusually difficult in Japan, because the country's warm, humid climate and acidic soil normally destroy ancient DNA before it can be studied. The team also sequenced the genome of a man called DO, who lived roughly 2300 years later during the Yayoi period, a time when rice farming was spreading across Japan. Comparing the two genomes showed that IY1 belonged to an early branch of the Jomon population, one that later contributed genes to people living in Japan today. The scientists also examined a gene connected to digesting starch. Both ancient individuals carried several copies of this gene, showing that genetic differences in starch digestion already existed in the region long before large-scale farming began. The findings were published in the Proceedings of the National Academy of Sciences.

Dinosaurs ranged from giants weighing more than 80 tons to hunters no bigger than a large dog, yet one thing never happened: no non-bird dinosaur ever became truly tiny. A new study by researchers at the American Museum of Natural History and Princeton University set out to explain this pattern. The team compared body sizes across mammals, birds, turtles and dinosaurs over more than 170 million years. In most animal groups, some species eventually evolved into extremely small forms. The smallest known non-bird dinosaur weighed about 450 grams, roughly the size of a large rabbit. That may sound small, but it is more than 200 times heavier than the bee hummingbird, the smallest living bird, which weighs less than 2 grams. About 75 percent of living mammal species and 90 percent of living bird species are smaller than that smallest dinosaur. Mathematical models that correctly predicted size patterns in mammals, birds and turtles failed for dinosaurs. Researchers suspect that early small mammals had already filled the ecological niches for tiny animals, leaving no space for miniature dinosaurs to evolve, until flight later allowed birds to escape that limit.