Today in Science: U.S. flu cases pass a grim benchmark

Cases likely to continue to rise in the coming weeks ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏  ͏ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­ ­

January 6, 2026—Small flying disks might soon surf sunlight in the upper atmosphere. Plus, flu cases in the U.S. pass a grim milestone, and astronomers spot a superhot galaxy cluster where no one thought it could be.  —Andrea Gawrylewski, Chief Newsletter Editor TODAY'S NEWS Artist's impression of a forming galaxy cluster in the early universe: radio jets from active galaxies are embedded in a hot intracluster atmosphere (red). Lingxiao Yuan Astronomers spotted a scorching hot galaxy cluster from the earliest days of the universe. It's five times hotter than experts thought could exist at that time.​ | 2 min read The CDC is reducing the recommended number of vaccines for children to those that protect against 11 diseases instead of the protections against 17 illnesses that it recommended previously. | 3 min read  Wegovy weight-loss pills have been approved. Here's how they might be prescribed. | 3 min read  Every January 1 scientists physically move the South Pole. Here's why. | 1 min read China plans to tighten rules for humanlike artificial intelligence, with a heavy emphasis on user safety and societal values. | 2 min read More News Support independent science journalism with a subscription to Scientific American. TOP STORIES Artist's impression of fliers carrying payloads. "Photophoretic Flight of Perforated Structures in Near-Space Conditions," by Benjamin C. Schafer et al., in Nature, Vol. 644; August 14, 2025. Sun-Powered Fliers Scientists designed centimeter-wide featherweight disks that could float without a power source in Earth's mesosphere, the thin air of Mars or other places with low levels of atmosphere. The tiny devices may even be able to carry a payload. The researchers simulated low atmosphere environments in a chamber and used lasers to mimic sunlight. They devised disks of various sizes and tested how well each stayed afloat.  How it works: The prototype disks are made from two thin, perforated membranes of aluminum oxide connected by minuscule vertical supports. They are kept aloft by a force called photophoresis: Gas molecules bounce more forcefully off the light-warmed side of an object than they do off the cooler one, creating airflow. In this case, the research team coated the bottom of each disk with chromium so it would absorb light and heat up more than the top. Gas molecules pinging off the lower part gained more momentum than those at the top, generating lift. Carefully calibrated holes in the disk's structure increased this thrust, using an effect called thermal transpiration which passively channels the air from cooler to warmer regions. Why this matters: Our mesosphere, which extends about 50 to 85 kilometers above the planet's surface, is sometimes called the "ignorosphere"—it's too high for aircraft and weather balloons to reach but too low for satellites to access, making it one of Earth's least-studied regions. In the future, swarms of these surfing disks might collect atmospheric data and relay telecommunications not only in Earth's mesosphere but also in the atmosphere of Mars. Flu Spike Doctor visits for flulike illnesses in the U.S. have reached their highest level in nearly 30 years, according to the CDC. So far this season, influenza viruses have led to more than 120,000 hospitalizations and 5,000 deaths, including nine children. More than 8 percent of all visits to a health care provider in the week ending on December 27 were for respiratory illness—the highest rate since the CDC started keeping tabs on such visits in 1997. Why this is happening: A new variant of the influenza A strain H3N2 that is known as subclade K may be driving up infections: the variant has been shown to carry mutations that may make this year's flu vaccine less effective. But the shots still provide some protection, especially against severe disease and death, experts say. The coming weeks: The new numbers don't cover the post-holiday-travel period, so the rates of doctor visits and hospitalizations could rise even further.

PUZZLER See if you can reassemble this dazzling image from the James Webb Space Telescope which shows the star-forming region NGC 604 in a galaxy about 2.73 million light-years from Earth.   More Jigsaw Puzzles In light of this intense flu season, I've been reading a lot lately about how important our gut microbiomes are for a well-functioning immune system. The gut microbiome consists of more than 100 trillion microbes including bacteria, fungi, and viruses. Vaccines are our strongest protection against respiratory illnesses like the flu, but the gut microbiome is the second-best line of defense against invading pathogens. How to improve your gut biota? Lots of fruits and veggies, plus some fermented foods (like kimchi and miso) have been shown to boost levels of beneficial bacteria. I hope you're navigating this fierce flu season as best you can.  Stay healthy and let me know what you think of this newsletter: newsletters@sciam.com. See you tomorrow!   —Andrea Gawrylewski, Chief Newsletter Editor

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