2026-09-06の世界

Have you looked up at the night sky this month? NASA says September 2026 brings an exciting lineup of skywatching events for anyone willing to step outside. On September 18, Venus will reach peak brightness as the evening star, shining low in the western sky after sunset and outshining every nearby star. Four days later, on September 22, the fall equinox arrives, marking the start of autumn in the Northern Hemisphere and the start of spring in the Southern Hemisphere, when day and night last almost the same length everywhere on Earth. The night before, on September 19, people around the world can join International Observe the Moon Night, a global event that invites everyone to look up and learn about our closest neighbor in space. Between September 14 and September 20, the Moon can guide stargazers toward Antares, a reddish star marking the heart of the constellation Scorpius, and then toward a group of stars called the Teapot in Sagittarius. Finally, on September 26, the Harvest Moon will rise in the east after sunset and appear close to Saturn, while faint Neptune forms a wide triangle with them, though it is far too dim to see without binoculars or a telescope. NASA reminds skywatchers that most of these sights need nothing more than clear skies and patient eyes.

What if life did not have to use just four DNA letters? Scientists at the University of California San Diego have shown that a key natural enzyme can accurately read an expanded genetic alphabet with eight letters instead of the usual four. This synthetic system, called Hachimoji DNA, adds two new artificial letter pairs to the four natural ones that make up every living thing on Earth. Led by Professor Dong Wang, the team studied RNA polymerase, the enzyme that reads DNA and builds RNA inside cells. Using high-resolution cryo-electron microscopy, powerful enough to reveal structures smaller than a single atom, the researchers watched the enzyme from the bacterium Escherichia coli recognize the four synthetic DNA letters through the same chemical and structural signals it uses for natural ones. In other words, the cell's own machinery did not need any special training to process artificial genetic information. The findings, published on September 2, 2026, in the journal Nature Communications, follow an earlier related study by the same team in the journal PNAS. Scientists hope this discovery will eventually help engineers design new medicines, diagnostic tools, and biological systems that store far more information than natural DNA ever could.

Was the so-called 'American cheetah' really a cheetah at all? New DNA evidence says no. For decades, scientists called the extinct Ice Age predator Miracinonyx trumani the American cheetah because of its slender, fast-running body, so similar to that of Africa's cheetahs. However, a new study published on September 4, 2026, in the journal Current Biology reveals that this ancient cat was actually most closely related to the living puma, also known as the mountain lion. Researchers led by scientists at the University of California, Santa Cruz, extracted ancient DNA from fossil remains and found that the two species split apart about 2.6 million years ago. Their cheetah-like bodies developed independently, through a process called convergent evolution, because both animals evolved to chase prey across open grasslands. The study also revealed a surprise about where this animal lived. While southern populations in places like Wyoming and Florida hunted a variety of grassland mammals, northern populations reached the Arctic region of Yukon, Canada, extending the species' known range 20 degrees of latitude farther north than scientists had previously realized. There, researchers believe these cats may have specialized in eating fish such as salmon, a diet never expected from a cheetah-like predator.

Can heat itself be used to make something cold? A research team from the Karlsruhe Institute of Technology (KIT) in Germany and the University of Tsukuba in Japan has built a device that does exactly that. Led by researchers Jingyuan Xu and Yi-Ting Hsiau, the team created what they call the world's first heat-driven elastocaloric cooling system. Instead of using an electric motor or a refrigerant gas like ordinary air conditioners, the system relies on two ultrathin films made of nickel-titanium, a shape-memory alloy. When warmed, the first film contracts and pulls on the second film. That motion stretches and releases the second film again and again, and this repeated stretching makes it cool down through a physical process called the elastocaloric effect. In tests, heating the device to 86 degrees Celsius produced a cooling effect of about 4 degrees at the component level, while the elastocaloric material itself changed temperature by nearly 13 degrees. The system even worked using a heat source as hot as 130 degrees Celsius. Because it needs no electricity to run, the researchers say it could someday cool computer processors using their own waste heat, or cool car electronics using heat from the engine, without adding to electricity bills. The study was published on August 28, 2026, in the journal Nature Energy.